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Thread: >> E21 FAQs and DIYs <<

  1. #1
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    E21 320i, e39 540i/6

    >> E21 FAQs and DIYs <<

    NOTE: Please refrain from posting comments, if you have something you would like to add to the FAQ please PM me. This thread is a constant work in progress that I still update whenever possible. Feel free to PM with any link or info you think should be added.

    Old FAQ Thread

    "Frequently Asked Questions and DIY" Table of Contents

    General E21 Info
    Wheels & Tires
    Suspension
    The 55mph Shimmy
    Replacing Rear Wheel Bearings
    Early/Late Strut Information and Differences
    Performance Upgrades
    Cutting Springs
    Lowering Springs
    Coil Overs
    How to Identify Coil-over Springs
    VW MK1 Strut Inserts
    Shocks
    Bushings
    Poly Control Arm Bushings
    Poly Subframe Mounts
    Sway Bars
    Slotted Rear Subframe
    Five lug hub conversion
    Strut Tower Braces
    "Alpina" frame rail brace
    Brakes
    Fuel System Troubleshooting & Tuning
    CIS Info
    Bosch CIS Manual
    Vacuum Leaks
    Hard Cold Start
    Cleaning the WUR
    Hard Warm Start
    Jumpering the Fuel Pump
    Re-adjust Base Mixture Setting
    Fine Tune Mixture Setting
    CIS Pressure Specs
    CIS Test Procedure
    Adjusting System Pressure
    Tuning the WUR
    Plumbing a Boost Sensing WUR
    Fuel Distributor Rebuild
    Fuel Leak Around Tanks
    Carb Swap
    Electrical
    Hazard Switch Repair
    Erratic wipers or turn signals -> see hazard switch
    Cleaning your fuse contacts
    Broken Odometer
    Odometer Rollback
    Tach Adjustment
    Pushbutton Start
    80 Amp Alternator Upgrade
    90 Amp Alternator Upgrade
    Wire Tuck
    Engine/Drivetrain
    Engine Modifications
    Adjusting Valve Clearance
    77-79 2.0L Smog Equipment Removal
    Remove Your A/C
    Electric Cooling Fan
    2 Speed Electric Cooling Fan Switch
    Cold Air Intake/Trunk Mounted Battery
    Advanced Timing
    Replacing Impulse Sender
    Hi Performance Ignition
    MSD Ignition
    Ignition Upgrade from Points to Electronic ('77-79)
    EDIS Conversion
    Megasquirt/EFI
    Injector Hole Plugs
    Performance M10 Build Info
    2.2L m10 build
    Header & Exhaust
    M10 Head Flow Comparison
    Stock Camshaft Specs
    M10 Cam Spec Database
    Rocker Retainers
    Larger 80mm Air Flow Meter
    65mm E12 throttle body
    Custom Throttle Cable

    Engine Swaps
    M20 Swap
    Early vs. Late m20 subframes
    M30 Swap
    M42/44 Swap
    S14 Swap
    M50/52/54 Swap

    Drivetrain
    Lightened Flywheel
    Heavy Duty Clutches
    Heavy Duty Engine Brace
    Transmission Gear Ratios
    Transmission Upgrades
    5 spd Tranny Swap
    Diff and Tranny upgrades (G265 trans swaps)
    Transmission Gear Ratios
    Differential Info
    LSD Rebuild
    Open diff to LSD Conversion
    Secondary Mount for Alpina Diff Cover
    E30 Diff Swap
    Half Shaft Rebuild
    Turbo Charging
    Aftermarket Kits
    Sizing a turbo
    Basic Turbo Parts List
    Building a Motor for Boost
    Turbo Camshaft Selection
    Turbocharging With CIS
    Plumbing a Boost Sensing WUR
    Turbo Build Threads
    Body & Interior
    Body
    Bumper Tuck
    Euro Bumpers
    Body Kits
    Euro Turn Signal Dual Filament DIY
    H4 hellas
    e30 Ellipsoids
    Quad Tail Lights
    Rust Repair
    Sunroof Repair
    Windshield Install

    Interior
    Upholstery & Carpet
    Recaro Restoration
    Parcel Shelf Reupholstery
    Dash Crack Repair
    Gauges
    120mph-140mph speedo
    Stereos
    Weight Reduction
    Last edited by jrcook320; 07-14-2016 at 09:03 AM. Reason: Automerged Doublepost

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  2. #2
    Join Date
    Oct 2004
    Location
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    Posts
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    My Cars
    E21 320i, e39 540i/6

    General E21 Info


    General E21 Info
    77-79 320i (US) - 3/76 to 9/79
    2.0L m10
    K-jetronic fuel injection
    8.1:1 CR
    BHP: 110 @ 5700
    Torque: 112 ft-lb @ 3750
    4 spd manual
    3.64 Open Diff
    23mm front sway bar - 3/76 to 9/77
    22mm front sway bar - 9/77 to 9/78
    22mm front sway bar - 10/78 to 9/79 - updated suspension design
    No rear sway bar
    0-60: 10.5 sec
    Top Speed: 106 mph

    80-83 320i (US) - 10/79 to 12/82
    1.8L m10
    K-jet w/ Lambda control, catalytic converter
    Compression Ratio: 8.8:1
    BHP: 101 @ 5800
    Torque: 100 ft-lb @ 4500
    Getrag 245 5 speed (80-82)
    Getrag 240 5 speed (83)
    3.91 Open Diff
    22mm front sway bar - 10/79 to 9/81
    23.5mm front sway bar - 9/81 to 12/82
    No rear sway bar
    0-60: 11.1 sec
    Top Speed: 105 mph

    "S" package The sport package was available between 80-83
    "S" package options (also available separately, including pre-facelift model years):
    Badge Delete
    3 Spoke Sport Wheel
    Leather shift knob
    Recaro Seats
    Front Air dam
    3.91 Limited Slip Differential (LSD) 25%
    23.5mm front sway bar
    16mm rear sway bar
    Sunroof
    Deluxe tool kit
    Fog lights
    AM/FM cassette stereo

    For more information, see the E21 Spotter's guides:
    e21 Spotters Guide.pdf

    BMW Parts ETK online (Exploded Parts Diagrams)
    Online parts cataloge with exploded diagrams & part #s of every BMW
    BMW Fans

    Real OEM

    Owner's manuals:
    '77 & '82 Owner’s Manuals


    '77 320i Factory Repair Manual
    '77 Repair Manual

    '81 320i Factory Repair Manual
    '81 Repair Manual
    Complete Printable Blue Book Service Manual-right click, save as- thanks to Jimbo!

    323i Factory Repair Manual
    http://eurocca.net/manuals/e21/

    Electrical Trouble Shooting Manuals:
    Electrical Trouble Shooting Manuals


    Parts suppliers:
    General Replacement Parts:
    bmaparts
    autohausaz
    autopartswarehouse
    Pelican Parts

    OEM/Mobile tradition/hard to find stuff:

    Walloth & Nesch - In Germany, hard to find euro stuff
    Maximillian Importing - Mobile Tradition online catalog

    OEM and Performance parts:
    Bavarian Autosport - excellent customer service, good performance stuff, can get anything the dealer can get and anything the dealer won’t.
    BMP Design - decent selection, good performance parts

    Custom Performance parts/bmw machining services:
    Top End Performance - offers lots of reasonably priced performance parts including headers, sway bars, coil overs, strut braces, clutches, forged pistons and machine work
    Metric Mechanic - rebuilt performance engines, trannies & differentials
    Korman
    Ireland Engineering
    Vac Motorsports - supplier of Dave Mcyntire's custom front suspension
    Aardvark Racing - 2002 focus but sell big brake kits (volvo girlings), recaros, rebuilt lsd's etc.

    E21 Parts Made by BFc Members
    Legioneering: E21 parts made by Legionnaires

    BMW Salvage Yards
    2002 AD - extensive selection of used parts
    Bavarian Auto Recycling - good used parts
    Bavarian Engine Exchange - rebuilt engines, tranies and diffs
    double02salvage

    Other E21 Forums
    Tricord - Very low activity, but still works and lots of great info
    Jeroen's E21 Network -Great forum/info source, especially for 323i's. Mostly UK/europe guys
    E21 Digest - The original, very antiquated but there may still be some good info here

    E21 Legion
    E21Legion.net

    Member's Build Threads - If you have a thread you'd like added just email me.

    Build Threads Database

    Member's Web Pages - If you have an e21 website you'd like added just email me.

    Kengineering.info - Ken Danielson's site
    77e21.info - Steve Hauer's 320i Site
    jrcook320.e21legion.net - Josh Cook's 320i Turbo

    Other E21 Sites
    International E21 Register.com
    Dave Mcintyre's E21
    Jeremy's E21

    E21 Buyer's Guide & New Owner Info:
    Buyer's Guide - Add link
    Poll: What did you pay for your e21?
    You just bought an e21, what maintenance do you do first?
    Back To Table of Contents
    Last edited by jrcook320; 08-18-2016 at 08:12 AM.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  3. #3
    Join Date
    Oct 2004
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    My Cars
    E21 320i, e39 540i/6
    Wheels & Tires

    Stock Wheel Size
    13 x 5.5 et18, 4x100 lug pattern, 57.1mm center bore
    Stock Tire Size 185/70R13

    Plus Sizing
    The most common upgrade wheel size is a 15x7 et12-15 with 205/50r15 tires. I’ve heard of 18mm offsets fitting on some wheels. On a 15” wheel a larger offset will not work because the inside lip of the wheel hits the tie rod ball joint. Some 16” and 17” wheels with higher offsets will fit because the diameter is large enough to clear the tie rods, but it still best to keep the outside of the rim as close to the wheel well as possible. On a 7" wide rim, regardless of diameter, that means aim for an offset between 12mm and 15mm.

    The E21 Aftermarket Wheel Database
    A listing of current forum members wheels including pictures and wheel dimensions:
    The e21 Aftermarket Wheel Database

    Wheel Technical Info
    Here is a diagram to illustrate what the offset measurement is actually measuring. Most wheels have higher positive offsets ranging between 20 and 40mm, meaning that the measurement from wheel centerline to hub is larger than what the e21 uses. 4x100 Honda and VW wheels will fit with spacers, but keep them hub centric and try keep your net offset at 15mm. For example, a 15x7 et40 wheel will require a 25mm spacer to give you a net 15mm offset.


    If everything I just said makes no sense to you , go here and learn how wheel dimensions are measured:
    Wheel Technical Information

    Wheel Bolts
    The stock wheel bolts are Conical 12x1.5x28mm. If you are running spacers you will have use longer bolts to have adequate thread penetration into the hub. If you're running a 20mm spacer, you'll need to buy 12x1.5x48mm wheel bolts (you may need round up to the nearest size). It is also a good idea to upgrade to lug studs with spacers. You can buy spacers and longer bolts and lug nuts from ECS Tuning & BMP.


    Tire Size Calculator
    If you’re trying to play around with various tire sizes to see what will work, try this tire calculator.
    Tire Size Calculator

    How to Build BBS RM and RS Wheels
    BBS RM and RS Wheels

    Wheel Restoration

    Wheel Polishing

    ETA Beta Repair and Restoration
    Last edited by jrcook320; 01-17-2012 at 11:27 AM.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  4. #4
    Join Date
    Oct 2004
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    My Cars
    E21 320i, e39 540i/6

    Suspension



    E21 Shimmy
    Most e21's suffer from a shimmy between 45-55 mph at some point in their life. This is mostly due to a poor front suspension design that relies on the sway bar to control fore and aft movement of the control arms in conjunction with worn suspension components.

    The 77-79 models have a 2 piece bushing design that is clamped by the sway bar washers. On the 80-83 models, the control arm, bushings and sway bar were redesigned presumably to improve this issue, and consist of a 1 piece metal sleaved bushing that presses into the control arm. These bushings are very soft and are mostly hollow and I consider them to be the weakest link in the front suspension.

    The best way to eliminate the shimmy is to first make sure the front suspension is in top shape. The ball joints, tie rods, upper strut bearings, wheel bearings, control arm bushings and steering rack bushings all need to be in excellent condition. Also make sure your wheels are properly balanced and that you have even tire wear. The steering rack bushings often get so oil saturated that they are more like gel than rubber. Bavauto sells poly steering rack bushings that will help control the shimmy and give the steering a nice crisp feel.

    Early/Late Strut Information and Differences
    Early/Late Strut Information and Differences

    Replacing Rear Wheel Bearings
    Replacing Rear Wheel Bearings

    Performance Upgrades
    The best thing you can do to your E21 is suspension. I would recommend starting with lowering springs and good shocks, then polyurethane bushings everywhere and sway bars, then strut tower braces, then camber adjustment.

    Cutting Springs
    For those that just want to go lower but are not really interested in performance, this is an acceptable alternative to shelling out cash for lowering springs if done properly.
    Cutting Springs

    Stock Spring Rates

    Lowering Springs
    The most common lowering springs are H&R and Eibachs. They will lower the car about 1.5" all around and offer similar price, quality and performance. They are still available from Bavarian Autosport and BMP. Eibachs or H&R's with Bilstien sports will knock the fillings out of your teeth (compared to stock), but for real racing you still want true coil overs.

    Eibach Spring Rates

    Coil overs
    Ground Control provides good value and is the best bang for the buck but there are better and more expensive options available from place like Top End Performance and Vac Motorsports. The very best is the LEDA setup already mentioned, but it costs thousands.

    coil over diy
    Coil Overs

    Spring Rates
    Coil Over Spring Rate Selection

    Coil Over Spring Rate Discussion

    How to Identify Coil-over Springs (from Drewdude320i)

    The Eibach ERS (eibach racing spring) used for the ground control coil-overs are labeled either in metric or english units. It follows the format,

    Metric:
    xxx.xx.xx

    the units are, (mm).(mm).(N/m)

    English:
    xxx.xxx.xxx

    the units are, (inch).(inch).(lb/inch)

    The first number of the series does NOT represent the spring rate. It represents the length of the spring itself. The second number represents the diameter of the spring, and the last number represents the spring rates.

    So if you have a number like this,

    Front 180.64.61
    Rears 200.64.44

    that means your springs are labeled in metric units. To convert them to English units (used in the US), you must...

    divide the first number by 25.4, divide the second by 25.4, and multiply the last number by 5.7

    This will give you,

    Front (8inches).(2.5inches).(350lb/inch)
    and
    Rear (7inches).(2.5inches).(250lb/inch)

    So the default spring rates are NOT 180/200 it is 350/250.

    VW MK1 Strut Inserts
    A common mod with coil overs on extremely lowered cars is to shorten the strut tubes and use VW MK1 strut inserts to maintain suspension travel.
    GTI struts/Shortened strut tubes

    Shocks
    Bilstein HD or Bilstien sport shocks are an excellect choice. The sports are valved very stiff (for the street, anyway) and are better choice for use with lowering springs.

    Sway Bars

    The stock sway bars are 22mm front and no sway bar rear. The 320is had 23.5mm front and a 16mm rear sway bar. The most commonly available aftermarket sway bars are from Suspension Techniques which were 25mm front and 19mm rear. They are NLA but they pop up from time to time on ebay and the forums. TEP still offers new sway bars in 25mm and 19mm.

    Bushings
    Replace as many bushings as you can with polyurethane. Many are still available new from Bavauto.com, BMP design, and TEP including steering rack bushings, rear trailing arm bushings, and sway bar bushings.

    Now available, custom made cast poly bushings for the e21 in multiple colors from Jester323i including swaybar, steering rack, subframe, control arm (pre and post facelift), trans mount, and m20 motor mount bushings!
    Colored Urethane Bushings

    Poly Front Control Arm Bushings
    I consider the front control arm bushings to be the weak link in the front suspension. Unfortunately there no longer any polyurethane upgrades available on the market. But, you still have a couple options.

    1) Fill your control arm bushings with Polyurethane casting compound:

    Front Control Arm Poly Bushing DIY #1 (thanks to Jester323)

    Front Control Arm Poly Bushing DIY #2

    2) I designed poly bushings for my car and TheNeek offered to machined a set up for me. He ended up machining many sets for forum members. You may be able to get him to do another group buy if you organize a large enough group.

    Poly CAB Group Buy


    3) Thanks to Jester, cast polyurethane press in bushings are now available in a design very similar to the machined bushings TheNeek and I designed. He also plans to start working on a design for the early models as well.

    Cast polyurethane press in bushings.

    Poly Subframe Mounts
    How to fill you subframe mounts with urethane

    Jester Performance poly filled subframe bushings

    E30 poly subframe bushing DIY

    Adjustable Rear Camber & Toe
    One issue that e21's have (and most early bmw's) is severe negative camber when lowered. One way to improve this is to buy k-mac camber eccentric trailing arm bushings from Bavarian Autosport or other vendor. The eccentrc bushins only allow a very small amount of adjustment which may not be enough to correct for severe camber issues. A better option is to slot the subframe to allow for camber adjustment.

    Rear Subframe Camber Slotting


    The best option is to weld plates onto the subframe and use eccentric bolts to adjust them. This is a much better setup since the adjustment won't move once tightened down. Ireland Engineering sells kits for the 2002 and e30 that also work for the e21. Here is a link to Steve’s thread on his Ireland modified subframe.

    Ireland Engineering Subframe Kit

    For more info, here's a great writeup on e30 subframe modifications:

    E30 subframe

    Five Lug Conversion

    5 lug conversion

    Strut tower braces
    Strut tower braces stiffen the chassis and make handling feel more crisp, especially the front strut brace. Bavarian Autosport and Walloth und. Nesch still carry brand new strut tower braces.

    Macfarland Performance Rear Strut Brace and Battery Tray

    You can also make your own rear strut brace pretty easily:
    Rear strut brace

    Alpina Frame Rail Brace

    Alpina used to add a bolt-in frame rail brace that tied the front frame rails together at the front sway bar attachment point, very similar to the "wonder bar" that came stock in some 3rd gen F-body's. E21's suffer from a weak core support that is prone to stress cracks, the aplina bar greatly stiffens the front of the car and users report crisper steering response and less body roll. Ken Danielson made a batch of reproduction braces and may still have some available. Now Jester323 is also selling his version of the brace.

    Jester's Frame Rail Brace

    My Welded-in Frame Rail Brace
    Last edited by jrcook320; 08-18-2016 at 08:19 AM. Reason: All Your Base Are Belong To Us.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  5. #5
    Join Date
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    My Cars
    E21 320i, e39 540i/6
    Brakes





    Bleeding Brake & Clutch Hydraulics
    Bleeding Brake and Clutch Hydrualics

    Vented Rotor Front Brake Upgrade with Volvo/Girling Calipers
    If you want to upgrade to vented rotors, the 323i calipers and rotors (same parts as the '77 320i) just bolt on. The only difference between vented and non vented front brake setups is a spacer in the caliper to accommodate the thicker vented rotor. The problem is that new OEM calipers for vented rotors are very expensive at about $400 each, and while listed at reasonable pricepoints most reman options are usually unavailable due to lack of cores, or parts suppliers simply list the wrong caliper for the '77 320i.

    A cheap alternative to sourcing the parts for stock vented brakes that still allows you to run stock vented 323i rotors is the volvo brake "upgrade". Rebuilt calipers cost about $60-$70 each, are 4 piston over the stock 2 piston, and have about 30% larger pad surface area. The larger pad results in improved pad wear, and the larger caliper results in more front brake torque than the stock 323i setup. This may or may not be a good thing depending on your car since generally you want to maintain bias close to stock, so a rear upgrade would be ideal to balance this kit back out. In any case, if you track your car, you will probably want something that will allow for larger rotors front and rear, but for the street and occasional autox, anything that allows the use of a vented rotor is better than the stock non vented setup.

    Volvo Brake Upgrade

    323i Rear Disc Convesion
    The easiest way to install disk brakes on the e21 is to swap E21 323I rear trailing arms. The trailing arms are different than the 4 cyl trailing arms with brackets for caliper mounting. The bearings and stub axles are also 323I specific and are not interchangeable. However the rotors are the same as used on the E30.
    DIY/caliper rebuild to come.

    E30 Rear Caliper conversion
    E30 Rear Caliper Upgrade

    VW MKII Rear Caliper conversion
    VW MKII rear caliper conversion

    Massive Lee's Big Brake Kit
    madhatter's big brake thread
    Lee's Website
    Last edited by jrcook320; 06-06-2016 at 03:59 PM.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  6. #6
    Join Date
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    Fuel System Troubleshooting & Tuning
    What is Bosch K-Jetronic, aka CIS?

    The BMW 320i and 323i are the only BMW’s to be equipped with CIS, aka Bosch K-jetronic. CIS stands for “Continuous Injection System”, so named because the injectors are mechanical valves that spray constantly rather than being pulsed the way efi injectors are. CIS was also used on many other European cars from the 70’s, ‘80’s, and even the ‘90’s, including Porsches, Vw’s, Audi’s, Ferraris, Lambo’s, Volvos, Mercedes and the Delorean to name a few. In its day the system was considered state of the art, though it’s strength is emissions, not performance. This system is almost entirely mechanical, in good tune is very robust, and is amazingly adaptive to performance modifications.

    First off, if you’re trying to trouble shoot a problem or are just asking a question, knowing what each component is and what it does will be a big help to you and to forum members as we try to answer your questions. Read and study the links below to learn what things are and what they do. There are a few components that often go by different names. The Control Pressure
    regulator (CPR) is the same thing as the Warm-up Regulator (WUR). The Air Flow Meter (AFM) is also called the Lift Plate or Sensor Plate. The Auxiliary Air Valve is also called the Idle Air Valve. I generally refer to the fuel distributor as the FD, the air flow meter as the AFM, and warm up regulator as the WUR.

    Bosch K-Jetronic Fuel Injection Manual - link to bosch factory manual detailing components and function of CIS components. It doesn't get any better than this.
    Bosch K-jet in detail (volvo specific) .pdf format
    K-jet.org
    Auto solve writeup on K-jet


    CIS trouble shooting:

    If you’re having CIS problems, the most valuable book you can buy is “How to tune and Modify Bosch Fuel Injection” by Ben Watson. To really be able to do full diagnostics of CIS you’ll also need to get a CIS pressure test kit.

    Hoffman TU-14C CIS pressure test kit

    Tool Aid 33865 C.I.S. K-Jetronic Fuel Injection Tester

    DIY CIS pressure gage


    Vacuum Leaks
    If you’re having ANY drivability issues such as hard starts, stalling, miss fire at part throttle, rough idle, off idle stumble, or no start, the first thing to do is check for vacuum leaks, then check again, then once more for good measure. The K-jet system is extremely sensitive to vacuum leaks, if there is even a small one the sensor plate won’t lift high enough and your mixture will be lean, sometimes to the point that the motor won’t even run.

    If you pull the dip stick or remove the oil cap with the motor running, it should stall. If it doesn't stall or present a significant change, it suggests that you are running with a gross vacuum leak that has been compensated for by a large fuel mixture adjustment.

    Common places to look for leaks are the oil cap seal; dipstick o-ring and connecting hose; cracked, loose or swollen vacuum lines; injector o-rings, intake manifold gaskets, brake booster and hose fittings; cracked or hardened crank case vent/aux air valve hoses particularly where they "T" into the intake boot; and most importantly the intake boot itself, particularly the port where the crank case vent hose fitting installs. It is very common for the crank case vent hoses to deteriorate and harden, even in as little as 5 years after being replaced. If the rubber is hardened or swollen, it needs replaced. It is extremely common for the port on the side of the intake boot to be swollen, loose, or even cracked.

    To check for leaks, spray starting fluid or wd40 around all suspect areas with the motor running, or if it doesn’t run do it while a helper cranks the motor over. If there is a leak the motor will suck the ether in through the leak and the idle will rise or the motor will sputter briefly. If it doubt, replace the intake boot and crank case vent hoses as visual inspect often fails to identify leaks.


    Hard Cold start/Rough running when cold
    The most common 2 problems I see being asked are hard cold starts and hard warm starts. Hard cold start can be caused by several issues, but the following are the most likely causes.

    1 - Cold Start Circuit- A hard cold start with no other driveability symptoms (such as rough idle, missing, etc) once the motor is started is likely cause by a problem with the cold start injector (aka 5th injector) or cold start circuit. Even if you have other driveability symptoms, it's a good idea to verify proper function of the cold start system before tearing into other fuel system components. The 5th injector is activated by the thermo time switch, located on the coolant neck at the front of the motor only during cranking depending on coolant temp. The thermo time switch sprays for a maximum of 8 seconds at -4 deg F. Opening time decreases 1 second for each 12 deg increase in temp, and the switch stays open above 95 deg F. The 5th injector can be sometimes cleaned if clogged, and the system is easily tested for proper function by removing the injector, placing it in a jar or can and cranking the engine. If it sprays, the system is working. If not, check to see if the injector sprays with 12v applied. If it does, it may be a wiring issue or a problem with the thermo time switch.

    Diagnosing the Cold Start Circuit

    2 - High Cold Control Pressure- A hard cold start, usually also accompanied by a rough or hunting idle or stalling when cold, is often caused by an incorrect (lean) mixture when the motor is cold. This can be caused by vacuum leaks (see above), but is also often due to a dirty or misadjusted WUR. Varnish, dirt or rust (and thus partial clogging or restriction) in the WUR will have a greater effect on cold control pressure than warm control pressure (and cold fuel mixture) because the WUR needs to flow more fuel to allow for the lower control pressure that a cold motor needs. As the WUR warms up the internal valve tightens and restricts flow anyway, so any restriction caused by varnish or dirt won’t effect warm control pressure as much.

    Often just cleaning the WUR can help. If this doesn’t help, then your options are to adjust your mixture to be richer, install another WUR, or do a full pressure test and make your WUR adjustable to bring it back in spec.

    WUR Servicing

    If this doesn’t help, then your options are to adjust your mixture to be richer, install another WUR, or do a full pressure test and make your WUR adjustable to bring it back in spec. See the "tuning your WUR section" below, or this link:
    How to tune your WUR

    Hard Warm/Hot Start
    A hard warm start is often due to an internal system leak causing a premature drop in system rest pressure (system fuel pressure after the motor is shut down). This results in vapor lock on a hot engine. There are 4 potential causes for this leak down are a leaking fuel pump check valve, leaking system pressure regulator o-rings, leaking accumulator, or leaking cold start injector. The accumulator can be tested easily by disconnecting the vent line and jumpering the fuel pump. It's easy to tell if there's a problem with the pressure regulator through simple inspection or the o-rings. If the cold start injector is leaking it will need replaced.
    1 - Leaking fuel pump check valve - Some say this is the most common cause. Early CIS pumps (pre '80) have a check valve integrated into the pump that cannot be replaced. Later style pumps have a replaceable valve that costs about $15. A leaking check valve will usually only cause hard warm starts. You can thread a later style valve into an early pump and in effect double stack valves, but you will also have to buy the correct acorn nut that the later style check valve uses to replace the early style banjo bolt.



    2 - Leaking Pressure Regulator - The system pressure regulator is located in the fuel distributor. Over time the o-ring seal compresses, degrades and can be prone to leaking after system shut down. It is easily inspected and replaced.

    How to replace pressure regulator o-rings

    3 - Leaking Accumulator - A leaking accumulator will cause hard warm starts, but if it's large enough it can bleed off enough pressure to keep the car from starting at all. To check for an accumulator leak, disconnect the small rubber line from the back of the accumulator and plug it with a golf tee or bolt and clamp it. Shove some fuel hose onto the nipple on the back of the accumulator and run it into a gas can. Jumper the fuel pump. Some fuel will spray out of the accumulator, this is normal as the rear chamber will have some fuel in it from the in-tank pump (the fuel line we disconnected). If the fuel flow does not stop then the diaphragm is leaking and it needs replaced.

    4 - Leaking injectors or cold start injector - To check for an injector or cold start injector leak, remove the injector and place it in a jar and jumper the pump. If it drips it leaks. If your main injectors are all dripping slightly, you may first want to try backing your mixture setting off a tad to make sure it's not just set too rich.
    Jumpering the Fuel Pump
    Most fuel system component testing you’ll need to do require you jumper the fuel pump.

    To jumper the pump you have to turn the ignition on for the pump to run. Jumper terminal 15 which is hot when the start-run bus is on (ignition switch on) and 87, which is the hot lead to the fuel pumps, WUR, and aux air valve. Note, i've recently found out from other members the orientation of the relay plug can be different than what was on my car, so make sure you connect correct terminals by checking the orientation of the plug:



    Re-Adjust Base Mixture Setting
    If you’ve done major fuel system work such as swapping fuel distributor, AFM, WUR, fixed major vacuum leaks or have a non-running car it may be a good idea to re-set your base mixture setting to correct a grossly misadjusted mixture. To do this, jumper the fuel pump. Turn the mixture screw clockwise (rich) until you hear the injectors start to spray. They will make an audible squeel/humming noise. Back off counter clockwise (lean) till they stop, then back off another 1/8 turn. This should get the mixture setting close enough for the car to at least run assuming there are no other problems.

    How to adjust the fuel mixture setting

    Fine Tuning Mixture Setting
    If you clean your WUR, swap fuel distributors or AFM, replace the fuel pump or even filter, or install hotrod parts like header, cam, exhaust or even cold air intake, expect to have to do some fine tuning of your mixture for it to be perfect or even run afterward. There are several ways a DIY'er can tune his own car with excellent results.
    1 - Adjust By Ear/Feal
    I adjusted my mixture by ear and feel with good results for years before I had a wideband O2 gage. It's not difficult to get a smooth running car with no gages or measuring equipment. With the motor running and oxygen sensor UNPLUGGED, adjust rich (CW) until idle starts to slow or stumble, then adjust lean (CCW) till it does the same, then adjust to half way between those 2 points. That's a starting point for tuning. Now drive the car and see how it feels. You're looking for smooth, steady idle, no off idle hesitation or stumble on throttle tip in. You should be able to snap the throttle and the motor should rev cleanly and freely and return to idle smoothly. At WOT you want a nice strong pull to readline. Once you have the motor running the way you want it, tune for the hardest "pull", or what feels strongest at WOT, without compromising drivability.

    Rules of thumb:
    1. On a throttle snap, if idle races before coming all the way down it suggests a lean mixture. If the idle dips below set idle speed it suggests a rich mixture.
    2. If you have a stumble or miss at part throttle cruise you likely have a slightly lean mixture

    2 - Adjust by O2 Sensor Voltage
    If you want to be more accurate for emmissions reasons, you can adjust the mixture by reading the voltage from the oxygen sensor. Unplug the O2 sensor first so the lambda system doesn't interfere with your adjustments. Make sure the motor is up to temp and the exhaust is hot since the O2 sensor has to be above 600 degrees for an accurate measurement. Bringing the motor up to operating temp by idling won't get it hot enough, you'll have to drive. Adjust the mixture until the O2 sensor voltage is at .45v. Now reconnect the O2 sensor and verify that you have a smooth idle. If it is oscillating you may need to tune slightly by ear to get a smooth idle with the sensor plugged in.

    3 - Adjust by Frequency Valve Duty Cycle
    You can also back probe the frequency valve with a dwell meter with the motor running and with the O2 sensor plugged in. With a dwell meter you can read the duty cycle of the valve, you target value is 45 degrees.

    4 - Narrow Band O2 Meter
    On a stock or even NA 320i you can get great results by installing a narrow band air/fuel ratio gage which only costs about $30 and uses the stock oxygen sensor. It is accurate right around stoichiometric ratio, which is really all you need to worry about on a stock motor, and is adequate to set your base mixture with. At WOT the fuel system will go richer than what it can read accurately, but on an NA motor it's not a safety issue as the fuel system will easily adapt to even a modded NA motor.

    5 - Wide Band O2 Meter
    If you're tuning for max power or have a turbo motor, you need to know your WOT AFR right down to the .x digit. A wide band is the only way to go here.
    The CIS Pressure Test
    CIS Pressure Specs
    For those that have a CIS pressure gage and just need to know the pressure specs, here they are for the 320i:

    Fuel pump delivery (as measured through the fuel return line): 750 cc's/30 seconds


    Cold control pressure:
    77-79 320i:
    50 deg = 10 psi
    75 deg = 18 psi
    100 deg = 26 psi

    80-83 320i:
    50 deg = 17 psi
    75 deg = 26 psi
    100 deg = 35 psi

    System Pressure:
    64-74 psi

    Warm control pressure:
    48-54 psi

    Rest pressure (leak test): above 22 psi for 20 minutes

    injector opening pressure: 45 psi

    Test Procedure

    [ame="http://www.youtube.com/watch?v=PcJl66wRKGg"]http://www.youtube.com/watch?v=PcJl66wRKGg[/ame]
    The pressure gage takes the place of the fuel line that runs from the top of the fuel distributor to the inlet of the WUR (the larger of the 2 ports). Make sure your shut off valve is on the WUR side of the pressure gage.

    1) Measure cold control pressure first. Make sure valve on your gage valve is open and the motor is stone cold. Disconnect the plug on the WUR so it doesn't heat up to warm control pressure while you measure. Jumper the fuel pump. You'll need to estimate what the cold control pressure is based on outside temp.

    2) Measure system pressure next. With the pump still jumpered, close the valve. You're now blocking flow to the WUR and the pressure above the control plunger will rise to equal the pressure in the lower chamber of the FD (system pressure).

    3) Next measure warm control pressure. Open the valve, start the car and let it come up to operating temp. If you can't start it, plug the WUR back in watch control pressure rise until it stops moving.

    4) Last, measure rest pressure (leak test). unjumper the fuel pump and watch the gage. It should stay above 22 psi for 20 minutes. If your rest pressure drops then fuel is leaking either at the check valve, system pressure regulator, accumulator, cold start injector, or WUR. See the warm start section above for procedures on how to test each component

    5) Injector flow test: To do a flow test properly, pull the injectors and place them in jars, or preferably graduated cylinders, and jumper the pump. At this point it's a good idea to check the injector tips for dripping (leaking). If all are dripping, try backing the mixture screw off 1/8 turn before assuming they all leak. To do the flow test, lift the sensor plate 1/4" for 30 seconds. The volume sprayed should be within 10% between all the injectors. If you pass that test, do it again with the sensor plate lifted half way up. Again, volume should be within 10%.

    Also check for a good spray pattern:


    If flow is not equal or you have a bad pattern, the only real way to clean the injectors is to back flush them.
    How to Back Flush CIS Injectors
    This is the correct procedure, as outlined by Bosch, for flushing fuel injectors.
    http://forums.bimmerforums.com/forum/showthread.php?t=1395779

    Adjusting System Pressure
    System pressure can be adjusted by adding or removing shims under the spring in the pressure regulator assembly. This can be used to bring system pressure back in to specification, or "tune" the fuel system outside of it's original operating parameters. For instance, raising system pressure above stock levels can increase the total flow capacity of the fuel distributor (note that higher system pressure WILL reduce fuel pump flow rate and may cause other problems). Note that adding shims will not raise system pressure to specification if the fuel pump is simply too weak.

    Adding shims will raise system pressure, while removing shims will lower system pressure. Shims were supplied in 2 thicknesses which raise system pressure in the following increments:

    .1mm - .85 psi
    .5mm - 4.3 psi

    Tuning the WUR to Adjust Control Pressure:
    You should never have to buy a new WUR unless the internal valve is rusty or the heating element is faulty. Instead you can make the WUR adjustable and correct any control pressure issues. This link is a good start on making cold control pressure adjustable but I consider it incomplete so I may write my own DIY someday:
    How to tune your WUR

    Here's a diagram I drew up on how to make both cold and warm control pressure adjustable by expanding this idea to also work on the main valve body. This is how my WUR is set up. At this time I have not writen a DIY on how to do this.


    Unwired Tools - Fully Programable Electronic WUR

    Custom CIS Tuning Theory Discussion

    Plumbing a Volvo 240 Fuel Distributor
    Volvo 240 turbo Fuel Distributor Connections

    Plumbing a Boost Sensing WUR
    Volvo 240 turbo WUR Connections

    Fuel Distributor Rebuild
    Porsche 928 Distributor Rebuild
    E21 Fuel Distributor Rebuild

    Fuel Leak Around Tanks
    Smell fuel every time you fill up, or see a puddle of gas if you overfill? It's likely just the tank vent lines.

    Fuel Tank O-ring and vent line replacement

    Carb Swap
    Goin' Carbed

    Weber Downdraft installation guide

    Tuning DCOE's
    Weber Tuning Tips
    Last edited by jrcook320; 08-18-2016 at 08:20 AM.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  7. #7
    Join Date
    Oct 2004
    Location
    Ohio
    Posts
    6,746
    My Cars
    E21 320i, e39 540i/6
    Electrical

    Hazard Switch Repair
    Hazard Switch Repair

    Erratic wipers or turn signals -> see hazard switch
    Hazard Switch Repair

    Cleaning your fuse contacts
    It is very common for the fuses in the e21 to corrode on a regular basis. Several times a year I have to get out and spin a fuse to get on of my headlights to work. It helps to clean the contacts with emry cloth and shoot some wd-40 on them to keep them clean.

    Broken Odometer
    If you're odometer has stopped working it's probably a split nylon gear. I was able to repair mine with superglue, you may have to just buy a new one from odometergears.com.

    odometergears.com

    Instrument Cluster Dissassembly

    Cracked Odometer Gear

    Odometer Rollback
    Odometer Rollback


    Tach Adjustment

    If yours is off or if you're installed a 6 cylinder tach in a 4 cyl, or vice versa
    Tach Adjustment

    Ignition Lock Cylinder Removal
    Ignition Removal

    Pushbutton Start
    This one's not all that common but I like it. My ignition switch broke and left me stranded at a friends house 2 hours from home. I pulled it twice trying to fix it to no avail, so we went to autozone and bought wire and switches to hot wire the car.
    Pushbutton Start

    90 Amp Alternator Upgrade
    90 Amp Alternator Upgrade

    Wire Tuck DIY
    Wire Tuck

    Last edited by jrcook320; 11-17-2010 at 05:58 PM.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  8. #8
    Join Date
    Oct 2004
    Location
    Ohio
    Posts
    6,746
    My Cars
    E21 320i, e39 540i/6
    Engine Modifications
    Adjusting M10 Valves
    m10 valve adjustment

    '77-79 2.0L Smog Equipment Removal
    Gain up to 15-20 hp by removing the smog equipment and upgrading a few components
    Smog Equipment Removal

    Remove Your A/C
    Not really an engine mod, but lets face it, it will cost more than the car is worth to fix it. It wieghs ~50 lbs. Get rid of it. Once you do you'll have to connect a wire to retain power to the heater blower. Go here for the wiring diagram on which wires to connect:
    Removing A/C- Wiring diagram

    Electric Cooling Fan
    Remove the belt driven fan and install a 14" or 16" electric fan. You will feel in on the butt dyno. Wire it in on the stock electric cooling fan circuit. If you've removed your A/C you can wire in a switch to take the place of the A/C control switch which pulls 12 volts off the heater circuit. Run a wire from that circuit to the plug behind the driver's side bright light. When your switch is closed it will trigger the fan relay. You will also need to run a diode inline (the stock A/C circuit had one that probably got removed when you pulled it) on that circuit to prevent current from your radiator temp switch back feeding into the heater circuit and blowing your heater fuse.

    Wiring an electric fan

    2 Speed Electric Cooling Fan Switch

    Cooling Upgrades
    A great upgrade for the e21 is a chevy-style 22x19x3 cross flow radiator which can be picked up on ebay or summitracing for less than $200. Ron Davis has a version of this radiator made specifically for the e21 with smaller 1.25" outlets.

    Ron Davis Aluminum Radiator 1

    Ron Davis Aluminum Radiator 2

    Chevy 22x19 Aluminum Radiator Upgrade - The same commonly available radiator as the Ron Davis, except without the m10 specific necks.


    One way to improve the efficiency of any cooling system or heat exchanger is to make sure the core is sealed to make sure all the available cooling air has to pass through the radiator rather than blow around it. Here was an experimental attemp at making block off plates/ducts to channel air to the radiator and prevent blow-by.

    Radiator Inlet Duct


    Cold Air Intake/Trunk Mounted Battery
    Cold air Intakes can be bought from TEP or MattE21. To properly install a cold air intake you have to move the battery to the trunk. You can pull a battery cable from an e30 or you can buy a 2 gage battery relocation kit from Summit Racing for fairly cheap and buy a standard battery hold down kit at any autoparts store.

    Custom Pre-80's Cold Air Intake

    '80+ Cold Air Intake Thread

    Cold Air Intake Heat Shield

    Cold Air Intake Heat Wrap

    Battery in Trunk DIY - by Madhatter

    Advanced Timing

    Advance your timing a few degrees. Either time the motor on the "Z" on the flywheel rather than the ball if you're using a timing light, or advance a degree or two and test it on the butt dyno. Advance the timing till you don't notice any difference. If you get ping, run higher grade fuel or back the timing back off.

    How to set your timing


    Ignition Upgrade from Points to Electronic ('77-79) from rocket859:

    The most common upgrade that gives you drivability and reliability will be switching from a distributor or points system to an electronic system. CraneCams makes a perfect kit to do this with the Fireball XR700. This kit makes the upgrade easy, and very accurate as compared from a distributor type system.

    LINKY: Crane electronic ignition

    Allison Electronic Ignition

    77-79 & 80-83 Hi Performance Ignition

    Cap and rotor from 77-79 model
    Wire set 110-8025 from Jegs: $66.99
    Bosch Red Coil: $37 from Ireland Engineering
    AR52 spark plugs: $12 from Jegs.

    For the '77-79 models, you will want to convert to electronic ignition first. The points won't like the hotter spark of the red coil. The '77-79 cap is socket style which allows for more wire options, like American V8's. The rotor has a smaller nose so it has less spark scatter at high rpms. The Bosch red coil allows you to run a higher gap, up to .050". To run the red coil, you have to either swap to the 77-79 cap, rotor, and plug wires to have compatible fittings, or you have to swap one end on the coil wire to the socket style fitting rather than the post style used in the 80-83 wires. Also, to run the AR 52 plugs, you have to use the older style plug wires due to the non-removable cap on the plug tip.

    For more info, see this thread:
    Help with Bosch Red Coil

    Replacing Impulse Sender
    Replacing Impulse Sender

    Distributor
    Distributor Rebuld

    MSD Ignition
    >add link


    EDIS Conversion
    If you're serious about ignition there is a lot of power to be had with a fully programmable ignition using off the shelf Ford parts and a Megajolt controller:

    EDIS Conversion Thread

    Converting to e30 318i EFI
    318i L-jet EFI

    Megasquirt/EFI

    megamanual.com

    DIYautotune.com FAQ page

    Steve's m10 Megasquirt ITB conversion

    Ken Danielson’s m10 Megasquirt conversion

    02 Again – M10 Megasquirt Parts
    02 Again has lots of parts for using the E30 318i intake manifold for Megasquirt including:
    - TPS adapter
    - EDIS VR sensor bracket
    - Idle Air Control Valve adapter
    - Throttle body adapter
    - Distributor plug

    Jester323's m20 Megasquirt Thread

    Boomer's Turbo m10 Megasquirt Thread

    Injector Hole Plugs


    Header & Exhaust
    Buy a used header off of ebay or new from TEP. Their header is decent and only costs $150. Also have a custom 2.25" exhaust made up at your local exhaust shop. Mandrel bent exhaust is even better, use mandrel bents from JC Whitney or Summitracing and have it welded up or weld your own. 2.25" is ideal for a stock motor with bolt ons, 2.5" is a little large unless you're turbo'd or have a hot NA motor.

    Factory Works Performance Exhaust
    If you want a complete, top notch bolt on exhaust that is dyno proven, buy Old Man's system here:
    http://www.factoryworks.com/320iexhaust.htm

    Performance M10 Build
    Block - The 1.8 and 2.0L blocks are the same. Some say the 2.0 block is heavier and stronger, but this is unverified. The stock bore is 89mm. The largest bore you can safely go with is 92mm. Some will say the safest max is 91mm, how risky you want to get is up to you.

    Rods - The stock 1.8 and 2.0 rods are forged, are 135mm and will hold all the power you'll ever make, NA or turbo. S14 rods are 144mm. If you're building an s14 cranked stroker, stick with the s14 rods for a better rod ratio.

    Crank - 1.8L = 71mm stroke, 2.0L = 80mm stroke, s14 = 84mm stoke. The 80mm 2.0 crank and rotating assembly will just drop right in to a 1.8L block. The only stock pistons that will work with the 1.8 head are the flat top 2.0 pistons which will give you very low 7.9:1 compression (great for a turbo, OK for NA). The best option is custom forged pistons which are available from TEP and Ireland Engineering, to name a few. Custom cast maxsil pistons are also available from Bavauto. If you use the 135mm rods & 2.0 crank your compression height will need to be 42.5mm. Be sure to have the rotating assembly balanced. The 80mm crank and 92mm bore will yield 2127cc's.

    The 84mm S14 crank can also be used in the m10 block with some minor clearance grinding of the block and custom machine work on the front timing cover to accept the larger s14 front crank seal. It is best to use the 144mm s14 rods. Your piston compression height will then need to be 31.5mm. With a 92mm bore this combination will give you 2234cc's. You could also have the s14 crank offset ground to 85mm and run .5mm oversized bearings which would give you 2360cc's (just a wild idea of mine, I've never seen this done). See Steve's 2.2L stroker build page:

    Steve's 2.2L stroker

    Max M10 Displacement Discussion

    M10 Compression Ratio Discussion

    Pistons - see TEP's or Ireland Engineering's website, give them a call.

    Head - Consider having the head ported/polished by someone who knows what they're doing like TEP or Metric Mechanic. You may also want to look into rocker retainers (see below).

    M10 Head Flow Comparison
    M10 Head Flow Comparison

    Camshaft - The stock cam is 264 degrees. Upgrading to a 278 or 280 will give you more top end, provided you have the intake and exhaust for the motor to breath there. The largest cam that you can run with CIS is a 292 which will still be streetable but you'll give up some midrange torque. Obviously with a large cam, stiffer valve springs will be in order. TEP and Ireland Engineering sell regrinds and new cams for a reasonable price, or you can pony up some serious cash and buy a Schrick cam from Bavauto.

    Cam Removal
    Steve Hauer's Cam Removal Tool

    Stock m10 cam specs (from factory blue book):
    base circle diameter: 26.7612mm
    Cam lift: 7.026mm
    Valve lift: 9.13mm (1.3 rocker ratio)
    114 deg lobe seperation

    Duration @ .020": 236*
    IVO :4* btdc, IVC:52* deg abdc,
    EVO: 52* bbdc, EVC: 4* atdc

    Duration @ .011": 264* (This is the equivalent to advertised duration, most cam specs you see are likely measured at this lift)
    IVO :18* btdc, IVC:65* deg abdc,
    EVO: 65* bbdc, EVC: 18* atdc

    M10 Cam Spec Data base:
    M10 Cam Spec Database

    Rocker Retainers - The "Achilles Heel" of the m10 is the rocker arms walking off the valves at high rpms. The stock retainer springs are too weak to keep the rocker over the valve stem and they walk down the rocker shaft and off the valve resulting in a broken rocker. A motor that sees lots of high rpm use may be saved by rocker retainers.

    Rocker Retainers

    Larger 80mm Air Flow Meter
    The stock 1.8L air flow meter has a 60mm sensor plate. This can become a restriction in the intake, especially on a motor with higher compression, free flow exhaust, CAI, and a cam. A simple remedy is to swap the upper half of the air flow meter with an 80mm unit from a ‘77-79 320i. This will gain you a few ponys on the top end and a definite boost on the butt dyno. Afterward you will have to re-adjust your mixture setting. Here's a few pics of the 2 side by side for comparison:

    AFM upgrade

    AFM upgrade/rebuild

    65mm E12 throttle body
    For my turbo system I installed a 65mm throttle body off of an e12. Here's pics of the install.

    E12 Throttle Body

    Custom Throttle Cable
    Engine Swaps
    M20 Swap
    Here's a nice writeup from Todor on his m20 swap.

    320i m20 swap

    Early vs. Late m20 subframes

    M30 Swap
    >add link - If you know of a writeup, pm me

    M42/44 Swap
    sonomaGTLN2's M42 Swap
    sonomaGTLN2's M42 Turbo Build

    S14 Swap
    S14 Swap

    M50/52/54 Swap
    M50 Swap

    M54 Swap
    Drivetrain
    Lightened Flywheel
    You can install a lightened flywheel for $150 from TEP. Weight will be reduced from about 20 lbs to about 13 lbs. Your motor will rev quicker and you'll make a little more power due to the reduced rotating mass of the engine.

    Better yet, Jason Miller of millersmule.com will lighten and surface your flywheel for a little less, and his technique takes more material from the outer edge of the flywheel for a lower moment of inertia. This means it will offer quicker revs and more hp gain than the TEP lightened flywheel.

    He also sells an all aluminum 228mm flywheel for around $375 which is a steal! I have his aluminum flywheel and couldn't be happier with it.

    Aluminum Flywheel discussion(page 3)

    Aluminum Flywheel

    Miller's Mule 228mm m10 Flywheel

    Heavy Duty Clutches
    If you have a hot m10 or have turbo'd or track your e21, you'll probably need a hi performance clutch. There are several options for either the 215mm clutch or the older 2002 228mm flywheel. Clutchnet.com and TEP both offer heavy duty, metallic 4 puc and 6 puc clutches in both sizes. TEP's disc supplier is Clutchnet but they couple them with a less expensive modified pressure plate. A 4 puc is very aggressive and on/off while a 6 puc is somewhat easier to engage smoothly and may require a stiffer pressure plate to equal the same holding power as a 4 puc.

    Clutch Discussion

    TEP/Clutchnet 215mm 4 puc

    Custom TEP/Clutchnet 228 6 puc


    Heavy Duty Engine Brace
    E21parts.net used to sells an engine brace to replace the engine vibration damper that was a very nice piece. I copied Fred's idea and found a cheap alternative at my local autoparts store:

    Engine Brace DIY

    Transmission Upgrades
    For those unfortunate souls burdened with an autotragic, here's a great DIY to swap in a manual:

    5 Speed Swap

    Transmission Gear Ratios

    Diff and Tranny upgrades (G265 trans swap)

    Differential
    Complete LSD Rebuild DIY
    Toyotech may also rebuild your diff for a fee, PM him.

    Replacing Clutches and Seals in an LSD

    Open Diff to LSD Discussion

    Secondary Mount for Alpina Diff Cover

    Homemade Double Mount Diff Cover

    E30 Diff Swap
    E30 Diff Swap

    Half Shaft Rebuild
    Rebuilding CV Joints

    Replacing CV Boots
    Last edited by jrcook320; 07-14-2016 at 09:04 AM.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  9. #9
    Join Date
    Oct 2004
    Location
    Ohio
    Posts
    6,746
    My Cars
    E21 320i, e39 540i/6

    Turbo Charging



    There are no readily available bolt-on turbo kits for the m10 on the market, but there are companies that will develop custom kits for your application. The tuner that has the most experience with the m10 in this department is Top End Performance who offers complete packages and any turbo accesories you need.

    There were several companies that developed kits back in the ‘80’s and these its turn up on forums and ebay from time to time. Among the most common are BAE/Century and Calloway. The kits are antiquated and poorly designed but they can be upgraded to offer decent performance.

    If you’re determined to turbo your car but are on a budget you’ll have to design and build it yourself. Start by reading the links below and also read Maximum Boost by Corky Bell. You'll need to know how to select the right turbo for your motor, which means you need an estimate on how much volume your motor is pumping and you'll need to know how to read compressor maps.

    Garrett Turbo Tech Basic - System Components

    Garrett Turbo Tech Advanced - How a Turbo System Works

    Garrett Turbo Tech Expert - Compressor Maps (How to Size a Turbo)

    Turbo Compressor Maps

    Garrett Turbos and Compressor Maps

    How to Read Compressor Maps



    To have the lb-min data you need to chart on a compressor map you can download my spreadsheet to calculate a good estimate of how much air flow your motor will produce at different pressure ratios. It is catered to the m10 but can easily be adapted to any motor with the right displacement and volumetric efficiency numbers.

    Turbo Airflow Calculations



    Basic Turbo Parts List
    The most important things you'll need are a turbo manifold, a properly sized turbo, and a way to manage fuel and timing.

    -Turbo header or manifold - TEP and Pro Turbo and now Boost Brother's currently sell new tubular manifolds for the m10. Other than that you either have to weld up your own or scrounge ebay for used stuff. I was able to find a rough casting of an old Dinan manifold on ebay for $100.

    -Turbo
    -Turbo oil supply/return lines
    -Turbo coolant lines
    -Down pipe/ 2.5"-3" exhaust
    -Charge pipes/pipe couplers
    -Intercooler
    -Blow off /bypass valve (1g DSM valves work well)
    -Larger throttle body
    -boost controller
    -Boost gage
    -Heavy duty clutch

    Turbo Oil Supply
    Tapped OIl Filter Flange

    Building a Motor for Boost

    Generally speaking, it's a good idea to start with a freshly rebuilt motor before you boost it. If you decide to boost a high mileage m10, at least make sure it's in tip top shape by doing a compression test, leak down test, etc. The stock m10 is very robust and can stand up to moderate boost levels reliably, up to 12-14 psi depending on compression ratio & tuning. With a good tune the stock head gasket will hold up to 15 lbs of boost. The piston crowns and ring lands are thick which allows the stock cast pistons to withstand the added heat and pressure of a turbo fairly well, and the rods and crank (2.0L crank only) are forged and will take whatever you throw at them. However, there are a few upgrades that are either good idea or are a must depending on how much you want to spend and how much boost you plan on running.

    If you have a 1.8L the biggest bang for the buck on a low budget turbo build is to swap in a 2.0L crank, rods and pistons (keep a matched set so they are balanced, or have them rebalanced at your machine shop). This will give you a ~7.9-8:1 compression ratio which will be more forgiving with tuning deficiencies and will allow you to safely run more boost on stock cast pistons. The .2L added displacement will also be good for an extra 20-30 hp depending on how much boost you decide to run. My crank, rods and pistons cost me $300 and I'm currently running 14 lbs of boost with stock head gasket, head bolts and pistons.

    To improve the robustness of the motor a cutting ring head gasket or MLS head gasket and ARP head studs are a good idea no matter what boost level you run. For higher boost levels, anything above 12-14 psi, you'll absolutely need forged pistons. I would go with JE, CP, or Weisco pistons in the 8.0-8.5:1 CR range which can be sourced from TEP, VAC, or IE in any compression ratio and compression height you want. The maximum bore you can safely run in the m10, especially for boost, is 91mm though some claim that some blocks can be safely bored to 92mm. If you want to get the most out of your motor I would also consider coatings for the piston skirts, crowns, combustion chambers, valves etc. Shot peening the rods and rockers is also a great way to improve the strength of those components.

    For lots more detail on how to build a motor for serious boost, read this thread:

    Building a 300 hp M10


    Turbo Camshaft Selection

    Depending on the size of your turbo and how wild your build is you want to stay away from too much overlap. If you're sizing the turbo to have a low boost threshold (say 3000 rpm or below) then you don't want a lot of overlap since the turbo will just blow right through the motor. I don't know where that cutoff of too much is, it's going to depend on a lot of factors. What you DO want is more valve lift, so a fairly low duration cam with high lift will really wake up a turbo motor and help it spool the turbo sooner. The stock cam is 264 degrees (I forget how much lift). I'm running a 280 cam and I'm probably giving up a little mid range between 3000 rpm and 3500 rpm. While my motor pulls hard once the turbo spools at 2800 rpm, it gets really nasty at 3500 when it comes on to the cam. I probably also make a little more power on the top end because of the cam so I'm happy with it's performance in my combo.

    TEP sells a 272 turbo grind cam that has more lift that the stock cam but still has low enough duration for more midrange efficiency. I've punched both my cam and TEP's turbo cam into desktop dyno and it confirms that the turbo cam makes a little more power in the midrange but gives up some top end power compaired to my 280 cam. The difference is around 5 hp.

    I've seen swedish guys running huge turbos & lots of boost run 300+ deg cams. There are several reason this works well for them:
    1) The turbo is too big to spool in the low-midrange where there is still too much valve overlap from a big cam, so they're not giving up boost by blowing through the motor. Instead, their cam is matched for the motor to breathe at the higher rpm where a large turbo is going to start to spool. I'm sure lots of planning goes into matching the boost threshold with the point that the cam becomes efficient. This is part of art of properly selecting parts that are going to work together rather than fight each other.

    2) They are also building their motors to breathe and make power at high rpms (like 8000+ rpm), thus a larger turbo that starts to spool at 4500 rpm paired with a cam that makes power from 4500 to 8500 rpm (these are arbitrary numbers) makes sense for them because they'll be able to make use of that power band.

    The rest of us guys running more streetable and mild turbo setups want to stick with something close to stock duration with higher valve lift. I'm running low boost levels and a small turbo so I need a cam that is going to let the motor breathe at lower rpms.


    Turbocharging With CIS

    It is possible to turbo with CIS and there are a couple members on this forum that have successfully done so. However, the STOCK CIS is only good for about 180 to maaaybe 200 hp if it's in tip top shape, and you will still need to upgrade a few components at a minimum to make your system safe.

    Minimum Fuel/Timing Components Needed
    1) Wide Band O2 meter - No matter what, spend the $250-$300 on a wide band O2 meter. Without this you have no idea what your fuel system is doing and you'll burn something up. This is as important as the turbo itself.

    2) Volvo 240 turbo or Audi 5000s WUR – You need a way to enrich the mixture under boost. The stock frequency valve can do this to some extent and may be adequate for low boost levels. The correct way to do this on CIS is to install a boost sensing WUR from a volvo 240 turbo or audi 5000s. Forget any garbage about boost switches firing a cold start injector. You want to aim for an AFR between 12:1 and 12.5:1.

    3) Volvo 240 turbo ignition canister – You will need a way to retard timing under boost. The easiest & cheapest way to do this is to install a boost retard/vacuum advance canister on your ignition distributor to pull timing under boost.

    If you start with those three things you'll be able to safely fuel up to 190-200 hp (maybe, I've seen no hard data on the stock fuel system, that's only what I've read). However, be advised that as far as k-jet goes, the stock fuel system is far from ideal. The fuel curve of the AFM bowl is not designed for a turbo 4 cylinder, and the fuel distributor will become a bottle neck in fuel flow.

    Upgraded CIS Components
    1) Volvo 240 turbo FD & AFM -Or- Porsche 924 turbo (931) FD & AFM (downdraft)
    2) MSD BTM -Or- EDIS

    A good option is to swap in a fuel distributor and AFM from a volvo 240 turbo as this system will mount in the stock FD/AFM location (on both the 1.8L and the 2.0L). You'll be able to fuel up to 220 hp, the AFM is 80mm (rather than the 60mm the 1.8L uses), the fuel curve is much better matched to a turbo application, and the FD will flow more fuel.

    You should be able to get more than 220hp out of that system by installing a fuel pump from a porsche 911 turbo (bosch "984" motorsport pump), removing the injector port filters, and shimming fuel pressure up to 85-90 psi. One good thing is that your stock injectors will pretty much flow as much as you can throw at them, provided you don't crank your system pressure too high.

    If you're not opposed to custom fuel supply & return lines and making mount brackets for your AFM, then the best fuel distributor/AFM combo for a 4 cylinder turbo is from a porsche 924 turbo (931). At 76mm, the AFM is slightly smaller than the Volvo and the fuel distributor is a smaller 4 cylinder casting (compared to the 6 cylinder casting of the volvo). But, the AFM is downdraft and has much better flow characteristics, and the FD can flow more fuel.

    My fuel system currently consists of the following components:
    -924 turbo (931) FD with port filters removed and system pressure at 95 psi
    -931 AFM
    -911 turbo (930) bosch motorsport fuel pump
    -Volvo 240 turbo WUR
    -Mercedes Benz 6.9L brass injectors
    -VW mk1 injector lines

    With this combo I'm now approaching 250hp which is currently the highest hp level I've seen on a 4 cyl turbo running straight k-jet with a single 4 cylinder FD/AFM and no auxillary injectors. This includes all of the guys on 924.org where I sourced my FD/AFM. I have also seen guys run v8 FD/AFM's with 2 injectors per cylinder, but the cost to do so is higher as the parts are harder to find.

    Plumbing a Boost Sensing WUR
    Volvo 240 turbo WUR Connections

    E21 Turbo Builds:
    - If you have a turbo build thread you'd like added, pm me.
    Jrcook320's Turbo Thread 1
    Jrcook320's Turbo Thread 2
    Jrcook320's Turbo Thread 3
    Fuel System Upgrades 1
    Fuel System Upgrades 2
    My Turbo Build Web Page

    DJ's turbo build thread

    sonomaGTLN2's M42 Turbo Build
    Last edited by jrcook320; 10-17-2012 at 12:08 AM. Reason: Automerged Doublepost

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  10. #10
    Join Date
    Oct 2004
    Location
    Ohio
    Posts
    6,746
    My Cars
    E21 320i, e39 540i/6

    Exterior



    Bumper Delete
    Front Bumper Delete DIY
    Front Bumper Delete Pics

    Bumper Tuck
    Bumper Tuck
    Bumper Tuck with Trimmed Front Bumper
    Macfarland Performance Front Bumper Tuck Brackets

    Euro Bumpers
    Front Euro Bumper Install
    Macfarland Performance Front Euro Bumper Brackets
    Difference Between Euro and US Rear Valance
    Mounting a Euro Rear Bumper on a US Car
    Prints for Euro Rear Bumper Brackets For US Valance
    Macfarland Performance Rear Euro Bumper Brackets for US valance
    Installing a Euro Rear Valance

    Body Kits
    DTMfiberwerkz - new reproduction body kits for the e21!
    E21 Air Dams
    Zender Over Bumper Kit

    Euro Turn Signal Dual Filament Mod
    http://forums.bimmerforums.com/forum...d.php?t=487916

    H4 hellas
    The best place to buy the best H4 lamps available:
    www.rallylights.com

    http://www.classicgarage.com/

    e30 Ellipsoids
    E30 Ellipsoid install - modified e21 buckets

    E30 Ellipsoids

    H4's vs. Ellipsoids

    Quad Taillights
    Quad Taillight DIY

    Rust Repair
    Joel323's rust repair
    Jester323's build thread

    Sunroof Repair
    Sunroof Repair

    Windshield Install
    Windshield Install

    Interior


    Seats/Upholstery
    veteranco.com - OEM style fabric, vinyl and carpets

    Recaro Restoration

    Parcel Shelf Reupholstery

    Dash Crack Repair
    Dash Crack Repair

    Gauges

    120mph-140mph speedo >add link

    Stereos
    E21 Audio Setups

    Weight Reduction
    Weight Reduction Discussion

    Here's a few things one can do to remove weight from the car (From Barry e36 m325):
    -remove the carpet and sound proofing about 20 pounds
    -remove the backseat about 10-15 lbs
    -Factory Recaros - 40 lbs each (jrcook320)
    -remove the sound system about 5-10 lbs
    -remove the front bumper about 25-30 lbs
    -remove the Air conditioning about 55-65 lbs
    -remove windows in the doors about 5-7 lbs each
    -remove the inner metal door panels about 5-7 lbs each (must be sawed out)
    -remove the spare tire and metal spare tire well about 25-30 lbs and 7-10 lbs (also must saw well out)
    -add fiberglass or carbon seats
    -swap rear window and 1/4 glass for plexiglass
    -remove heater core
    -add lightweight wheels
    -remove window washer assembly
    -add a fiberglass or carbon fiber hood, trunk, and door panels. These are available from Kormann and Vacmotorsports
    Last edited by jrcook320; 10-16-2012 at 11:51 PM.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  11. #11
    Join Date
    Oct 2010
    Location
    Maui
    Posts
    15
    My Cars
    1982 320i

    Aloha

    I really want to thank you guys for posting this information. I just solved my warm/hard start issues with your posting JR and it saved me alot of time and money. Turned out to be the accumulator but I replaced the pressure regulator o rings anyway. BMW parts on Maui are limited and expensive so accurate troubleshooting is a must. Keep up the good work and know that you are appreciated. Mahalo.

  12. #12
    Join Date
    Feb 2012
    Location
    California
    Posts
    1
    My Cars
    bmw
    I've been a car Junkie eversince my love for German made cars complete change my mechanical skills in terms of taking good care of the car I own, fixing them and some kind of DIY modifications on the engine. I love bimmers coz they look aggressive and fast while not sacrificing the car's looks and comfort in luxury. This info gave a precise ideas of how to lighten the car and give it superior power by removing some of it's luxurious parts. I like the idea of loosing some weight from the car and putting more muscle under the hood. Hopefully the car would be introduced in it's hybrid version and some new BMW parts to give it more grunt against the American Muscle cars.
    wow that's really great. thanks for the infos here it did really saved half of my life. whew.

  13. #13
    Join Date
    Feb 2012
    Location
    New albany in. USA
    Posts
    5
    My Cars
    2005 x5. 2001Mroadster 1

    320i stalls when u step on the accelerator

    hey I have a couple bmws and Im thnking about buying a 1983 320i
    Its rusty the floor boards and trunk are almost a total waste the interior is really good 7/10 However the engine stalls if you try to give it too much gas or if the gas tank is pretty low The current owner is a good guy and thinks the fuel tank is dirty and when u give it too much gas is sucks up debris A mechainic friend says the '83 has two fuel pumps and one or both are probably messed up Your thread points to vacuum hoses He wants $1000 for the car I guess my question is what is the most likely issue with a car that starts up ok,Idles ok but cuts out and dies when you press on the accelerator too much or too fast?
    thanks ps incase you cant tell Im a real newb and I really want to stop taking my cars to the dealer

  14. #14
    Join Date
    Oct 2012
    Location
    Hobart, Tas, Australia
    Posts
    3
    My Cars
    1982 BMW E21

    Unsure of part name.

    I have an '82 323 i and there is a part that I think controls the air and fuel mixture that functions when the engine is cold - I could be wrong. On some, it has a screw on one end and on others it doesn't. It is quite small about 4 inches long and it is not electrical. I need the part name please. It sits at the very back of the engine bay with a pipe at each end. Sorry - I'm a bit of a dead head with these things...

    Also, like everyone else on here, I have a cold start issue with my E21. Here's what happens: I pump the accelerator pedal - start it and it starts ok and idles for about 30 seconds and then seems to almost/will cut out until I put my foot on the accelerator again and it revs fine - then it seems to flood with fuel smoke coming out the exhaust pipe and a severe fuel smell. The car rocks as this happens. I need to keep my foot on the accelerator pedal at low revs until the temp gauge reaches the bottom of the blue (which can be say - 3 - 5 minutes) - then it's fine. I know that my cold start injector is not working as there is currently no power going to it - which I will get fixed but surely this is not the WHOLE problem. Anything above say 14 degrees, none of this occurs and it idles fine (albeit a little bit rough) I have had to do this procedure every morning for 2 years and I am completely over it. Any help would be most appreciated or anyone else have the same problem and they fixed it? Much appreciated.
    Last edited by Tassie65; 10-06-2012 at 09:13 PM. Reason: Automerged Doublepost

  15. #15
    Join Date
    Dec 2012
    Location
    Denver
    Posts
    346
    My Cars
    E34M30
    This thread is such a great help. Thanks to everyone for compiling all this info.

  16. #16
    Join Date
    Mar 2017
    Location
    AL-GA
    Posts
    181
    My Cars
    1981 bmw 320i
    This thread is great. Thanks for all the effort.
    The Bosch CIS Manual is broken and only takes you to viglink an no where else.

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