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Thread: E32 Rough Idle & Shimmy – the Ultimate Fault Guide

  1. #1
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    E32 Rough Idle & Shimmy – the Ultimate Fault Guide

    refers mainly to E32 - Rough Idle & Shimmy – the Ultimate Guide!

    (Including information about Catalytic Converters)
    Thanks to Johan for examples/pictures on his website – to follow the link click here
    http://bmwe32.masscom.net/

    1) Spark plugs, plug wires, rotor & ignition coils - Clean and inspect.
    2) Check compression – poor cylinder head compression is common for an older car. Big job to fix this.
    3) Use a good fuel-injector cleaning treatment into the tank – take it for a good run.
    4) Change fuel filter.
    5) Remove and clean injectors – might need to replace injectors.
    6) Vacuum hose to fuel pressure regulator – might be cracked/worn (buy a new one)
    7) Rubber hose between Airflow Meter and throttle – cracked?
    8) Mass Airflow meter/sensor – if dirty clean it up. Bad Air Flow Meter will cause flat spots in acceleration or erratic spots in the throttle depending on the opening of the airflow meter not usually a complete lack of power.
    9) Hose to air filter – cracked?
    10) Air filter – replace if dirty, check seals.
    11) Distributor cap – if eroded and worn - changed to new one
    12) Check fuel pressure - Replace the Fuel Pressure Regulator. Might need to replace Fuel Pump(s) and fuel filter(s).
    13) Check and Adjust valves - throttle valves, PCV valve behind intake runner, Idle Control Valve (ICV).
    • ICV Idle Control Valve. Remove and clean it with brake parts cleaner. This regulates the air coming in to your intake manifold when the throttle body is closed and it tends to get dirty, sticky and the motor inside could not turn the valve properly.
    • Idle control valve sometime sticks open – causes issues when in Idle
    14) Throttle Body - Clean it out and replace the gasket (can use gasket material cut to size).
    15) Check all Vacuum lines.
    16) Conduct a ‘leak down test’ on all exhaust valves.
    17) Check for Oxygen (O2) sensor function tests.
    18) Check the wide-open throttle switch under the gas pedal. (not for EML equipped E32)
    19) Check throttle position switch on the throttle body.
    20) Make sure connections on battery (under back seat) are very clean. Use wire brush.
    21) Check rubber boot between the Mass Air Flow and the DKM.
    22) Check for intake manifold gasket leak
    23) Have the transmission checked for correct functioning – (by mechanic).
    24) Make sure there are no other sources of drag in the driveline.
    25) Checked coolant sensor.

    Try the RESET Procedure before all of above.
    Notes:
    The reset procedure is billed as a ‘cheap fix’. It does often give good immediate results, however if there is something wrong with your car (any number of issues as listed above) then over a 2-8 week period the car will likely return to its original state.
    The reset procedure removes all mean values stored by your onboard computer that control engine timing, fuel use etc. As you continue to drive the car, the stored values ‘average out’ to best suit the engine condition.
    If your car has for example a leaking intake manifold gasket or broken O2 sensors, the readings are quickly going to become ‘corrupted’ with incorrect information. This can lead to the engine running too rich or too lean (check your sparks for evidence). Within a short period of time the car will return to rough idle as the underlying problem has not been fixed. That said – the reset procedure can reset values that are no longer applicable. You may have replaced something on the car (e.g. Catalytic Converters) thus causing a sudden change in normal engine running. The readings stored over 10-20 years will suddenly not suit you recently modified car. The car will however read new values in and average out over time. The Reset procedure simply speeds that process up.
    The long and short of it is that this procedure can sometimes fix rough idle and transmission timing and seems to improve the cars performance. However with existing underlying issues as outlined above – it won’t be long before the problems return. Perhaps this procedure could be used if you’re trying to sell your E32 ;-)
    Procedure:
    1. Disconnect battery cables, first negative, then positive.
    2. Cover and protect the battery posts! Leave no potential of a battery short circuit.
    3. Turn ignition to position II.
    4. Connect both battery cables ("SHORT") for at least 10 minutes. This step drains a capacitor in the ECU/TCU. (Covered the battery with a thick, dry shop towel to prevent actually shorting the battery! – careful of arc welding in my back seat! As the battery was in place, and the cables aren't that long, you could use a very long Craftsman screwdriver and two small vice-grips to actually clamp the negative and positive cables to the metal shank of the screwdriver.
    5. Wait 10 minutes - then ignition off, key out.
    6. Reconnect battery positive, then negative.
    7. OBC says "PPPP", reset time. Start and idle the engine for 5 minutes, then off for five, then out for a drive.
    8. Now, with the car in lowest gear (one or two depending on your make), accelerate until at least 5000 rpm is reached. Allow the car to slow to idle, and then repeat two more times. Let the car idle for 5 minutes. All Done!
    9. Idle should smooth out over 10-12 miles; shifts should be immediately smoother.

    SHIMMY @ 80mph – likely culprits
    Check the following in this order:
    1) Wheel alignment by a recommended mechanic (dynamic balancing)
    2) Check your brake pads!
    3) Check thrust arm bushings. (Some call them upper control arms). Bushing can go after several thousand km’s
    4) Replace/check tie-rod center, and Left & Right tie-rods, pitman arm, idler arm http://www.bmwe34.net/E34main/Mainte...ering_link.htm
    5) Check Struts / Shock absorbers while your there.
    6) Sometimes (rarely) disks are warped – replace them (machining is just as expensive if not more).
    Details about the Catalytic converter:
    The catalytic converter is our main line of defense against air pollution, so it's important to make sure it is functioning efficiently and passing exhaust without creating undue restrictions that might reduce performance, fuel economy or emissions. That's one of the reasons for periodic vehicle emissions testing. If the converter isn't working, you won't pass the test.
    If the converter is plugged, it will create a restriction in your exhaust system. The buildup of backpressure will cause a drastic drop in engine performance and fuel economy, and may even cause the engine to stall after it starts if the blockage is severe.
    The easiest test for converter plugging is done with a vacuum gauge. Connect the gauge to a source of intake vacuum on the intake manifold, carburetor or throttle body. Note the reading at idle, then raise and hold engine speed at 2,500. The needle will drop when you first open the throttle, but should then rise and stabilize. If the vacuum reading starts to drop, pressure may be backing up in the exhaust system.
    You can also try to measure backpressure directly. If your engine has air injection, disconnect the check valve from the distribution manifold, and connect a low pressure gauge. Or, remove the oxygen sensor and take your reading at its hole in the manifold or headpipe. Refer to the backpressure specs for the application. Generally speaking, more than 1.25 psi of backpressure at idle, or more than 3 psi at 2,000 rpm tells you there's an exhaust restriction.
    If there appears to be an exhaust restriction, disconnect the exhaust pipe just aft of the converter to relieve pressure and recheck the readings. CAUTION: The pipes will be hot so wait awhile for things to cool down. If vacuum goes up and/or backpressure drops, the problem isn't not a plugged converter but a plugged muffler or collapsed pipe. If there's little or no change in readings, the converter is plugged.
    Just because a converter is passing gas doesn't mean it is okay. If the catalyst inside is contaminated or worn out, high carbon monoxide (CO) and/or hydrocarbon (HC) readings will be present in the exhaust. If you have access to a high temperature digital pyrometer (or an oven thermometer will do), check the converter's temperature fore and aft. A good converter will usually run 100 degrees F hotter at its outlet than its inlet. Little or no temperature change would indicate low efficiency, or a problem with the converter's air supply. Converters need supplemental oxygen in the exhaust to reburn pollutants, so if the air injection system or aspirator valve isn't doing its job the converter can't do its job either.
    Check the air injection pump, belt and check valve. If you suspect that the check valve is allowing exhaust to flow backwards, remove it and blow through both ends. It should let air pass in one direction, but not in the other. Examine the air injection manifold, too, because it tends to rust out and leak air. Check the diverter valve to make sure it is working correctly, too. It should be routing air to the converter when the engine is at normal temperature.
    On engines with aspirator valves instead of air pumps, you should hear and/or feel the fluttering of the internal flapper as the engine is idling.
    CAUSES OF CONVERTER FAILURES
    Fouling, clogging, melt-down and breakage of the ceramic substrate inside a converter are common conditions that can cause problems. Plugging is usually the end result of a melt-down, which occurs because the converter gets too hot. This happens because the engine is dumping unburned fuel into the exhaust. The excess fuel lights off inside the converter and sends temperatures soaring. If it gets hot enough, the ceramic substrate that carries the catalyst melts.
    The unburned fuel may be getting into the exhaust because of a bad spark plug or valve, but an overly rich air/fuel mixture is another possibility. In older carbureted engines, a heavy or misadjusted carburetor float may be the underlying cause. But on newer engines with "feedback" carburetion or electronic fuel injection, the engine may not be going into "closed loop" (the normal mode where the computer regulates the air/fuel mixture to minimize emissions).
    A bad oxygen sensor or coolant sensor may be giving the computer bogus information. A sluggish or dead O2 sensor will make the computer think the exhaust is running lean, so the computer will try to compensate by making the fuel mixture rich. A coolant sensor that always indicates a cold engine will also keep the system in open loop, which means a steady diet of excess fuel. But it might not be the sensor's fault. A thermostat that's stuck open or is too cold for the application can prevent the engine from reaching its normal operating temperature. So if your converter has failed and needs to be replaced, the engine should be diagnosed for any underlying problems before the new converter is installed.
    Another cause of converter clogging and contamination is excessive oil consumption. Worn valve guides or seals can allow oil to be sucked into the engine's combustion chambers. The same goes for worn or damaged rings or cylinders. Oil can form a great deal of carbon, and metals present in the oil can contaminate the catalyst. A compression check or leak-down test will tell you if the rings are leaking, while a fluttering vacuum gauge needle will help you identify worn valve guides.
    Last edited by shogun; 03-20-2017 at 10:15 PM.
    Shogun tricks and tips for the E32 series are HERE!

  2. #2
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    the special one for the 750 M70

    rough idle/no power M70 -basics to check

    Basic points for fault analysis at a 750i/iL E32 for the DIYer

    engine problems such as rough idle/no power:


    - 1. -
    The easiest way is to have a possibility for fault analysis at the dealer with a DIS, or a PEAKE fault code tool, or the stomp test.
    The delaer testing computer is of course the best and most comprehensive one and gives online results while the engine is running, while for example the PEAKE just can show stored results in the system. ]
    Fault code test/stomp test

    http://twrite.org/shogunnew/data/controlsystems.html

    -2.-
    Important is that the EML light in the dash goes on for about 2 seconds when the ignition is set to position 2, after that it should disappear. Actually there are 2 bulbs for the EML, and one of it functions as a resistor for the other one.
    How the EML works: http://www.europeantransmission.com/...MWtechinfo.htm

    Cockpit/cluster repair:

    If the EML light does not come on when ignition is in position 2, the engine will always run in limpmode. So this has to be repaired. Not many professional shops know that, they just replace the complete cluster or ECU modules because of lack of knowledge.

    Remove the cluster from cockpit, see Johan and Sean's page. Pay special attention when you have an airbag, all mentioned on Johan's page. Link on my website if you do not know it.

    Repair method:
    The EML light should come on when engine is started in ignition position 2 for about 2-3 seconds and then go off. This is a kind of test for the 2 bulbs inside the motherboard of the cluster. One bulb acts as a kind of resistor for the other, to speak in my no-electric expert words.
    People have paid hundreds or thousands of $ to repair shops because they replaced unnecessarily MOTRONICS, EML and other parts of the car, as the car was in limp mode and they could not solve the problem.
    Limp mode, also known as failsafe mode, limits throttle openings etc and runs off a preprogrammed setting, limits rpm and speed as well...
    Vmax after 2 minutes approx.50 kmh in 3rd gear, at max. 1500 RPM, no ability to climp uphill and so on.

    A member of 7er.com has just made a write-up with pics. Of course it is in German, but the pics are most important to understand. Main points I just translate in brief into English, I will omit the general info on how to remove the cluster from the dash, and other points known to all of you which are regular visitors on this board.
    Pin 16-17, the only connected soldering points of the "white" plug are to be connected to the "upper contacts" of the 2 EML lights.
    Option: Pin 12 of the "brown" plug to be connected (soldered) with the "lower contacts" of the EML lights.
    As connector he used hot glue.
    Leave cable long enough to assemble the cluster again.

    Notes: No guarantee for correct translation. It is your car when you repair it. Description is based on a cluster from a 750iL from 05/1989.

    If you are not able to see the pics in the link to the German board, you might have to register first. Easily done, no cost involved, and they have a very good repair page, done and maintained mainly by Erich = shogun ;-)

    http://www.7-forum.com/forum/showthread.html?t=41084
    http://www.7-forum.com/forum/attachm...achmentid=5109
    http://www.7-forum.com/forum/attachm...achmentid=5110
    http://www.7-forum.com/forum/attachm...achmentid=5111

    Johan: http://bmwe32.masscom.net/johan/eml_bulb/eml_bulb.html
    Pins location:

    1 26
    2 25
    3 24
    4 23
    5 22
    6 21
    7 20
    8 19
    9 18
    10 17
    11 16
    12 15
    13 14

    - 3. - In case the EML works fine, check the gear and trans mode in the cluster. If they are not shown, engine runs in limpmode.
    repair procedures http://www.bimmerboard.com/forums/posts/244408
    - 4. - Visual check of the intake system.
    Use brake cleaner and spray it when engine is running in all areas around the intake system, but NOT into the air intake duct directly. If the RPM changes, you have an air leak somewhere. Check all the rubber connections in the intake system
    - 5. - Should all this not help, check by cylinder banl to allocate the side of the engine which makes a problem. Remove one after the other the connector from the throttling valves and check if the engine stops when one is not connected. Can be done while engine is running, connecting and disconnecting. In case one cylinder bank stops the engine, concentrate on that side. But remember, the intake system you see in the car on the passenger side actually goes into the cylinder bank of the driver side and vice versa. Start changing parts from one side to the other, throttling valve, MAF. If the fault moves to the other side, you have the culprit.
    - 6. - I so far nothing could be found, check the area of the oxy sensors. Remove one plug of the 2 after the other, if a big change in engine running, it could be the sensors or one of them.
    -7.- All this provided that you already have made the basic checks such as distributor caps and rotors (often the first ones are still inside), crankshaft sensors, cylinder identification sensors, spark plugs etc.

    A good help is the ECU pinout, where you have the data you should be able to measure
    details here http://www.bimmerboard.com/forums/posts/155581/

    A Bentley Repair Manual is a must for you, as there are many data, although sometimes we find mistakes. Wiring data and other hints you find here under electronics http://www.e38.org/e32/

    throttle valve cleaning http://www.mwrench.com/Whitepapers/DKMotorcleanup.pdf
    Last edited by shogun; 03-05-2022 at 06:08 PM.
    Shogun tricks and tips for the E32 series are HERE!

  3. #3
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    is there any info on how to clean the maf censor or afm?



  4. #4
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    Auto Clinic: Maintain Your MAF Sensor, A Power Surge Precaution and More

    Cleaning hot-wire MAF sensors with CRC MAF Sensor Cleaner might improve your engine's performance. PHOTOGRAPH BY JAMES WESTMAN.

    By Mike Allen
    Published in the August 2006 issue.

    Cleaned Out

    Q: My dashboard Check Engine light came on and a scan tool said Code P0171 was stored on my car's computer. I checked the O2 sensor, mass airflow sensor (MAF), etc. All voltage and resistances were well within the factory specs. So, I took the car to the dealer, and they replaced the MAF sensor. Since then, the car has been running fine and the light stays off. Why? Is there any secret?

    A: Mass airflow sensors constantly measure the amount of air entering the intake manifold. This lets the engine management computer know how much gasoline to inject into the cylinders for proper combustion. Hot-wire-type sensors, like you have, work by keeping a short piece of wire or film at a constant, elevated temperature. An electrical current is applied to the wire to maintain its temperature; the amount of current necessary to maintain the temperature is proportional to the mass of cool air flowing past it. Sounds complicated, but there are no moving parts and the response rate is very fast. So far, so good.

    Eventually, dirt and oily film bake onto the wire, insulating it from the cooler air--and when the engine management computer sees a value for air mass that's too far out of range, it sets an error code. Periodically, there's a cleaning cycle during which the wire is heated to a very high temperature right after engine shutdown. This burns off deposits.

    When this cleaning cycle fails to remove all of the contaminants, you're supposed to replace the MAF sensor. According to almost every manufacturer, it's not recommended or even possible to clean the delicate wires. Of course, they're selling those sensors, so their motivation might be suspect. Next time, I'd try cleaning it first--what do you have to lose? I used to use aerosol carb cleaner, but CRC MAF Sensor Cleaner is new and less prone to dissolving other components in the MAF sensor. Do yourself a favor and remove the MAF sensor from the vehicle before attempting to clean it. Also, I'd make sure the air filter housing, air filter and all associated ducting are intact, clean inside and not leaking dirt. This will keep you from needing to clean or replace the MAF sensor anytime soon.


    Power Surge

    Q: Can welding on a vehicle damage its electronics? I have heard that I should disconnect the battery, computer, alternator and other electrical components before welding. This was the policy of a company I used to work for that made and mounted truck bodies. But many companies, including the one I work for now, never disconnect anything. After all, ships and steel-frame buildings with grounded frame systems don't require it. I have done structural work, such as extending truck frames and welding on tractors and on farm machinery connected to tractors, with no ill effects.

    A: The sensors for your car's engine management computer can operate at millivolt voltages and at milliamp currents. A MIG or stick welder can reach 50 volts and hundreds of amps. Most of the time, the computer harness is insulated enough to prevent damage. A poor ground can cause eddy currents powerful enough to fry the electronics. If I need to weld on a car, I remove the computer and disconnect the battery ground cable to isolate the car's electrical system.

    Free as Air

    Q: I have a 1994 Lincoln Town Car with 161,000 miles. After parking the car I hear air venting from the air suspension system. After I restart the car, the air pump will run for 30 to 60 seconds. This started about three months ago. Is there an adjustment or an easy fix to correct this problem?

    A: The compressor runs after you start the car because the air springs lose pressure and sag. They are just rubber bags, and there is a fair amount of plastic tubing hooking them to the pump. When you restart the car, the ride-height sensor sees the suspension is too low, and the pump runs until it comes back up to the required height. The leak continues while you're driving, but you probably don't notice the pump running while the car is running. There might be a problem with the ride-height sensor--but, more than likely, it's just a leak. If you're lucky, it's a hose damaged by road debris or a loose fitting, which is easy to fix. A leaky air bag will cost a lot more to replace.



    Every car made since 1996 has an OBD-II (On-Board Diagnostics) connector underdash. It's where the mechanic plugs in his scan tool to check your car's health. A pro-grade scan tool can cost thousands. CarMD costs $90, which is close to what a mechanic would charge you to use his scanner to diagnose a problem. The CarMD uses the memory and screen on a Windows-based computer to display the data from your car's engine management system and to look up information from CarMD's Web site. There you can find an explanation of what all those trouble codes really mean, and some insight into what might be causing them.

    For the M30 AFM, Paul Axford has the best write up with pics, Paul Axford's Web Site -- Maintaining the BMW 730i "big six", see under Cleaning the Air Flow Meter (AFM) potentiometer
    https://web.archive.org/web/20110824...730i/index.htm
    Last edited by shogun; 03-05-2022 at 06:14 PM.
    Shogun tricks and tips for the E32 series are HERE!

  5. #5
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    Mr Shogun,
    Aloha, I need your expertise on my 1991 735iL. She is rattling after running it for 30 minutes. Sounded like it was coming from the front or the passenger side. All bolts are secure. Could it be the CAT? my cousin told me they could just bypass the CAT. Here in Hawaii, there's no enforcements on CAT's. Thanks again. Happy New Year to all your loved ones.

  6. #6
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    I just found out some reasons why mine is running rich and smelling.. im gonna follow the list! Thanks Erich!

    shimmy:
    I'd add Hub Centric Rings (in case doesnt have the oems). That was my case after changing the whole front end parts.
    Last edited by shogun; 08-07-2013 at 08:06 AM.
    OO=[ ][ ]=OO
    Quote Originally Posted by MCA View Post
    7er BMW > Econoboxes

  7. #7
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    Synesthesia: try to better allocate the rattling before you start replacing. Get a mechanics stethoscope or a steel pipe or long screwdriver and listen to the sound with that. Can be many things. I just found on my car a bad bearing on the belt tensioner which made noise, and in winter the blower fan motor starts making noise, when you sit in the car, it sounds the noise comes from engine room, but actually it is the blower motor. Found that out by switching off the blower fan/AC and all was quiet.

    M70: Weird electrical problem - M70 throttle wiring is hinky, sends DK into spasm , with pic of damaged wires http://www.bimmerboard.com/forums/posts/644209/
    Last edited by shogun; 08-08-2023 at 10:57 PM.
    Shogun tricks and tips for the E32 series are HERE!

  8. #8
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    next problem solved, No EML Light http://twrite.org/shogunnew/diagnosis/emlfailure.html

    Emergency mysterious EML reset
    1. All doors, hood and trunk must be closed (not locked). Open the drivers door WIDE
    2. Now close the drivers door and lock the car.
    3. Unlock the car again and again open the drivers door WIDE.
    4. Sit down on driver's seat and close the drivers door (NOT locking)
    5. Push the brake pedal and keep it pushed down.
    6. Now insert the ignition key into the ignition lockand set it on position 1.
    7. Remove your foot from brake pedal (release) and remove the key from the ignition key.
    Your engine should (temporarily) run without EML message, = no limpmode
    Last edited by shogun; 06-05-2022 at 01:52 AM.
    Shogun tricks and tips for the E32 series are HERE!

  9. #9
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    Motronic Basic, Motronic 1.1, Motronic 1.2, and Motronic 1.3 Fuel Injection Tech Article

    http://www.hiperformancestore.com/Motronic.htm
    Shogun tricks and tips for the E32 series are HERE!

  10. #10
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    Problem:
    1994 750il: Had 1221 code,replaced a leaking vacuum hose and all was fine for a bit.
    Now have the 1222 code and the car runs like crap on idle like when I get to a stop light/ sign it sounds terrible but as soon as I step on the gas it sounds fine and has plenty of power. Has brand new o2 sensors, spark plugs, dis cap and rotors.
    Would the fuel pressure regulators cause this to happen if they are bad? The car also has a hard start and I removed the vacuum lines from the regulators and they leak fuel. Could the regulators be the whole cause of the codes and hard start?


    Cause and remedy:
    Got the parts, finished installing the new regulators and they fixed it, fixed hard start, crappy idle, and check engine light.

    Description of operation: fuel pressure regulator
    Depending on requirements, the fuel pressure regulator regulates a low or high fuel pressure. This requirement is set with the help of the pressure regulator. Depending on the engine's operating state, less or more fuel is needed:
    - at idle speed, less fuel
    - at full load, considerably more fuel.
    The injection rate is precision-adjusted by means of the injection time; the injection time is controlled by the DME.
    The partial vacuum in the intake manifold serves as engine load information for pressure regulation. The diaphragm of the pressure regulator is actuated with this partial vacuum.
    A partial vacuum builds up in the intake manifold during idling operation or in overrun mode. Depending on the partial vacuum value, the fuel pressure decreases starting out from the nominal value. The nominal value is stamped in the fuel pressure regulator housing.
    At full load, the partial vacuum in the intake manifold is approximately equal to zero. The fuel pressure regulator regulates the fuel pressure to the nominal value stamped in the housing
    Last edited by shogun; 01-25-2013 at 11:51 PM.
    Shogun tricks and tips for the E32 series are HERE!

  11. #11
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    ECU Pinout and Electrical tests http://www.rtsauto.com/ecu-pinout-an...cal-tests-e30/

    cylinder compression test, workshop manual states:

    M30B30 and M30B35 compression nominal value at least 10-11 bar, 142 - 156 psi

    M70B50 compression nominal value, approx. equal value for all cylinders 10 - 12 bar, 142 - 170 psi, S70B56 11 - 13 bar

    M60B30 and M60B4 at least 10-12 bar
    Last edited by shogun; 12-28-2021 at 06:25 AM.
    Shogun tricks and tips for the E32 series are HERE!

  12. #12
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    TIMM'S BMW E32 50MPH - 60MPH SHIMMY
    http://www.meeknet.co.uk/e32/E32_Shimmy.htm

    Some additional info:
    Some months back we have been chasing a vibration in the steering wheel on an E32 750iL that we could not pinpoint. It came on at about those speeds as usual.
    The whole of the front suspension had been gone through. New upper and lower arms, sway bars, end links. Wheels have been checked again and again on a friend's balancing machine. Tie rod ends were tight. Then we were starting to wonder if the brake rotors might be out of balance. He had installed some cheapo brake disks a year ago. Usually on good brand ones
    you will see a mill mark on the side where it was balanced, but we could not find any real mill marks on these cheap brake disks, unless they were already covered by rust or polished.
    Warped rotor would only cause vibration upon braking but not just driving along.
    Bad tire or balancing if it comes on only at a certain speed was already eliminated as possible cause. We even put the wheels on the balancing machine and checked the running of the tires.
    Even we checked the lug nuts, if they were original.
    Any rotor manufacturer not balancing them would be out of business pretty quick, but the quality of balancing is the question and the quality control as well as the precision machinery used and the maintenance. So we checked both front rotors on the simple tire balancing machine of my friend and found both had unbalance. We ground them slightly around the hub area to get them in balance. Problem solved. Better let a specialized shop do this, or do it at your own risk.

    Another possibility of rotor unbalance:
    Braking shake is coming from rotor but you can make a kind of balance by the wheel bolts.
    1st take off all wheel bolts, remove the wheel, and losen disk lock bolt,
    2nd install 3 wheel bolts with brake disk, then the disk perfectly fits on the hub
    3rd tighten disk hex lock nut and release wheel bolts
    finally install wheel with tire and tighten wheel lug bolts.
    this is also a kind of balancing techniq

    Also: when fitting new discs, make sure you clean any rust off the hub so that the rotor seats properly on the hub. This can also cause unbalance.
    Last edited by shogun; 03-20-2017 at 09:55 PM.

  13. #13
    Join Date
    Feb 2009
    Location
    Islamabad, Pakistan
    Posts
    160
    My Cars
    89 E32 7 & 1971 1600
    EML light should turn on for all E32`s ,735i also?? it never turns on my cluster i assume the engine is in failsafe mode,my car is on dual fuel so i least bothered but one can feel its just not the same on petrol

  14. #14
    Join Date
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    11/88 E32 750iL+98 E36M3
    Most probably your E32 735 does not have EML. EML is fly by wire = no bowden cable from the accel to the throttle valve, but a potentiometer and there is a motor on the throttle valve which controls the throttle. With EML there is also no idle control valve, because the EML also controls the idle.
    The Electronic Throttle Control System (EML) regulates the operation of the throttle valve(s).
    The scope of EML design on BMW engines provides:
    • Throttle valve positioning for optimum starting
    • Precise idle speed regulation without the use of an external idle control valve/circuit
    • Progressive throttle opening curves matched to the driving program (with EGS/AGS interface)
    • Cruise control operation without additional control modules and linkages
    • Automatic synchronization of the throttles (airflow balancing) for two independent banks,throughout the entire engine speed range (M70, S70, M73 engines only)
    • Intake air volume control for ASC/DSC (Automatic Slip Control/Directional Stability Control) systems
    • Maximum road speed limiting
    • Emergency “Failsafe” operation in the event of component failures
    The EML control module is a link in the total scope of Engine Management Control. The EML is interfaced with other control modules to complete the management system, which includes:
    • ECM(s) - Except E46 (EML integrated in MS42.0 ECM)
    • EGS/AGS
    • ABS/ASC
    The main components of the EML system are:
    • Accelerator pedal position sensor (PWG)
    • Accelerator pedal position sensor (driver’s wish sensor - integrated in throttle housing,
    E46 MS42.0)
    • Throttle valve assembly/assemblies with electronic control motor(s) - DK/MDK
    • EML control module (MS42.0 ECM - E46)
    Throttle valve control is managed electronically, using an electric motor(s), without the use of mechanical linkages or cables (except E46 - MDK).
    The EML system uses a microprocessor to convert the input signal for the position of the accelerator pedal into output commands for control of the throttle valve. The position of the
    pedal is merely a request to the control module for throttle opening. The EML module processes this input request along with other pertinent operating parameters. The throttle valve
    is then moved to its proper position according to specific control unit programming. The total scope of output control functions for the EML includes: http://www.europeantransmission.com/...MWtechinfo.htm

    In case your 735 has the bowden cable on the thottle body like this http://www.nmia.com/~dgnrg/tc2.jpg = no EML
    740 has never EML, always bowden cable.
    750 always
    735 sometimes only
    Here this 735 in Lahore, Pakistan has EML http://forums.bimmerforums.com/forum...ML-light-issue
    Last edited by shogun; 03-05-2022 at 06:17 PM.
    Shogun tricks and tips for the E32 series are HERE!

  15. #15
    Join Date
    Feb 2009
    Location
    Islamabad, Pakistan
    Posts
    160
    My Cars
    89 E32 7 & 1971 1600
    WTf and all this time i had been working on the cluster trying to find out why the dam bulbs wont come on :/ , i do have those bulbs on my cluster and they are intact also i checked it.... NO EML just checked when i press the pedal with the hood open the manual linkage from the pedal actuates the throttle so it was all in my head and not the car HEHE will check the zero to 60 now it should be 9.2sec rite ,thanks

    - - - Updated - - -

    very informative and intersting post from IRfan if you can see this get in touch with me irfan 923008500700 my num DA36664= my vin

  16. #16
    Join Date
    Nov 2013
    Location
    Altamonte Springs, FL
    Posts
    56
    My Cars
    1/88 735i (E32)
    Shogun - how do I make the Automatic Air actually turn off (and stay off - it's so loud that I can't think when it's on - I plan a fix for that but it's back burner due to front end and other driving issues). Thanks.

  17. #17
    Join Date
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    11/88 E32 750iL+98 E36M3
    You mean the blower fan always runs at high, or cannot be adjusted? The blower fan speed is regulated by the socalled sword
    Thread: E32/34 sword repair info concentrated
    http://www.bimmernut.com/forum/7-ser...centrated.html
    Shogun tricks and tips for the E32 series are HERE!

  18. #18
    Join Date
    Nov 2013
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    Altamonte Springs, FL
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    My Cars
    1/88 735i (E32)
    No matter the position of any of the buttons it randomly turns on / off - so going to look at your link on this and hopefully have a quiet ride home after work tomorrow.

  19. #19
    Join Date
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    shimmy and shaking

    here the story how we just solved it finally

    We worked with 2 DIY guys for 4 days (2 full weekends) on an E32 Alpina B12, we have never had such a problem before. When the owner told us his trouble we could almostnot believe it. The other pro shop where he had the car gave up on this problem and he found our hobby E32 DIY group thru the internet.
    Car was driving nice under normal conditions (small shimmy in the steering) with even the wide Alpina wheels/tires till it got on rough street surface or whatever and then the whole car started severe shaking and was undriveable that people got scared. So we tested a lot. Wheel alignment, complete new upper/lower arms in front, new stabilizers, new dogbones, new beer cans, new center bearing (that was definitely shot), new engine mounts, new trans mounts, changed the complete front shocks, springs + shock mounts from another 750 into the B12, changed all 4 wheels from another B12 to that car: test drove it, 30-50 km fine, suddenly it starts shaking again very heavy.

    We finally found it, these parts all had some play in the joints and caused slight vibrations, plus old worn upper and lower arms, dogbones, beer cans, engine mounts, trans mounts,
    a combination of wear on many parts
    http://www.bmwe34.net/E34main/Mainte...ering_link.htm
    especially the ball joints of the center link, the steering gear input and output shaft had heavy wear, all this combined under certain conditions when all these items were at their peak critical vibrations at the same time, that made this heavy shaking. Each part has a critical vibration.The original shop which services that car gave up and they could not find the fault.
    We have another steering gear from a parts E32 750 and installed that, new steering links, pitman arm etc, problem solved.

    Also: when you adjust the handbrake too much and never change the springs in the handbrake, the spring weakens http://bmwe32.masscom.net/sean750/ad...rkingBrake.htm
    the clutch parts can start shattering against the drum causing also unbalance. This was told to me by an old very experienced Meister from BMW.

    Mechanical unbalance – motor, coupling, or driven equipment
    Mechanical effects – looseness, rubbing, bearings, etc.
    External effects - base, driven equipment, misalignment, etc.
    Resonance, critical speeds, reed critical etc.

    Critical speed - From Wikipedia, the free encyclopedia
    In solid mechanics, in the field of rotordynamics, the critical speed is the theoretical angular velocity that excites the natural frequency of a rotating object, such as a shaft, propeller, leadscrew, or gear. As the speed of rotation approaches the object's natural frequency, the object begins to resonate, which dramatically increases system vibration. The resulting resonance occurs regardless of orientation. When the rotational speed is equal to the numerical value of the natural vibration, then that speed is referred to as critical speed.
    Critical speed of shafts
    All rotating shafts, even in the absence of external load, will deflect during rotation. The unbalanced mass of the rotating object causes deflection that will create resonant vibration at certain speeds, known as the critical speeds. The magnitude of deflection depends upon the following:
    (a) stiffness of the shaft and its support(b) total mass of shaft and attached parts(c) unbalance of the mass with respect to the axis of rotation(d) the amount of damping in the system
    In general, it is necessary to calculate the critical speed of a rotating shaft, such as a fan shaft, in order to avoid issues with noise and vibration.
    Shogun tricks and tips for the E32 series are HERE!

  20. #20
    Join Date
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    This info was posted by rv8flyboy on Bimmerboard and it is worth to post here for reference:

    Subject: passing this on, by request. Author: rv8flyboy Posted on: 2013-12-19


    symptoms were a complete dead on one side but all the individual parts could be swapped between banks, CPS, DME etc.

    i suggested to use a scope to compare signals on a running engine.


    Mark Mallett
    Hi Gert, I'm having a strange problem with my 750. I know your heavy into the electronics in these beasties and maybe you have some ideas.
    I have a no spark condition on cylinders 7-12. By no spark I mean literally nothing using just a wire inserted into the coil to check for spark.
    EML light is functioning correctly. Goes off after 2 seconds. Check Engine light comes on immediately after starting and remains on sometimes blinking. No problems with instruments. Starts and runs beautiful even if on only bank 1. DIS is unrevealing so far. Shows 0 rpms on DME 2 and oxygen sensor fault. Disconnecting DME 2 does not trigger an EML light but check engine light stays off in this situation.

    So far as of late I have done the following:

    Bad coil earlier on 1-6. Replaced both coils with new factory OEM. This solved no start problem.
    Two new CPS. The old had been through 3 engines. Checked wiring for CPS to and from DME 2. All good.
    Original fuel pumps were weak. Replaced with TRE Performance pumps.
    Tested fuel pumps. Did a flow test, checked the electrical connections. All good.
    Removed Ford 19lb injectors. Replaced with OEM flow tested. No more flooding problems.
    Performed a compression test. 160lb+ all cyl.
    Replaced battery with a new 1000cca. Old was weak 11.2. Have 13.9v idling at obc.
    Switched DME's. No change, same banks runs (1-6)
    Switched MAF's. No change.
    Both DKE move.
    Switched oxygen sensor connections. Ran poorly. No change for 7-12. Swapped back.
    Switched coils. No change. Swapped back.
    Checked all connections to and from coil 2 to DME 2. All check good.
    Checked all spark plug wires and doughnuts. All check good.
    New bosch caps and rotors.
    New plugs.
    Checked all fuse's and their connections, all good.

    I'm suspecting a problem with the EML, but I am far from an M70 expert.
    This one has me scratching my head lol. Any ideas?

    gert
    Hi Mark Well, you already did a lot of stuff, at this point i would get an oscilloscope and compare inputs to each DME with the car running cause clearly somewhere a signal is missing. After all, you can swap DME's so they are good. You could try another EML?? There is a signal from the OBC to ea…

    Mark Mallett
    Thanks Gert. Great idea. I know someone with a scope. Something I have been thinking about learning. Will get started on this. Obc and antitheft....hadn't considered this. And I just removed the previous owners old alarm system...hmmm. Will definitely look into this too. Thanks again, Mark

    then success

    Mark
    I thought you might be interested to know what I found.

    You were right, checking signals at the ebox with the engine running I found the lost signal. Turns out that I was losing signal for cps on dme2. This was caused by broken wires shorted inside the shielded cps wiring located just before the ebox. This area in the wiring harness is too delicate to open, so I ran another shielded wire (2 wire stereo cabling, with wire wrapping) to dme2. Bank 2 immediately came to life. No CEL or EML afterwards.

    It's worth noting that the short between the two wires did not present itself until dme2 was physically connected in the ebox. When the wiring was moved or even wiggled, the connection shorted internally. (Disconnect and all was good, Connect and shorted)

    Feel free to repost these emails to your favorite boards, or in emails, especially it may be of some help to someone. Finally out of the dog house with my wife! Lol!

    Thanks again for the help and ideas.

    Regards, Mark
    Shogun tricks and tips for the E32 series are HERE!

  21. #21
    Join Date
    Jan 2005
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    11/88 E32 750iL+98 E36M3

    additional info

    Always check the battery and alternator, battery test under load.

    Low voltage:

    the engine might even start with the low battery, but it is well known that our cars electronics play crazy when the battery voltage is low, not only the MOTRONIC, but also the IHKA and other modules/relays.

    Ronald Trochelmann of Performing Imports told me many years ago the following:


    Low voltage will set EML only if it drops below 11V for more than 90sec.

    Low voltage will also cause problems with the IKHA (heater/ac), memory for seats/steering and transmission will go into limp mode.

    Mismatched tires WILL set EML light if vehicle has traction since it reads all 4 wheel speed sensors and gets an "implausable" reading.

    Just for clarification: I am a 20 year BMW Master with 3 PhD's from Germany in Engineering and I know these systems better than almost anyone. I did 12 years of R&D on these system for a manufactorer in Germany, so I am not some "Key Board" mechanic or read some crap on the internet.
    Ronald Trochelmann
    ---------------------
    M70 crankshaft sensor and donut identification info http://forums.bimmerforums.com/forum...nder-ID-Sensor
    Last edited by shogun; 07-07-2014 at 06:20 AM.
    Shogun tricks and tips for the E32 series are HERE!

  22. #22
    Join Date
    Jan 2005
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    Japan
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    11/88 E32 750iL+98 E36M3
    Here some pics to repair the EML light in the cluster. Usually the board is damaged there, the bulbs are fine.
    Pin 16-17, the only connected soldering points of the "white" plug are to be connected to the "upper contacts" of the 2 EML lights.
    Attached Images Attached Images
    Shogun tricks and tips for the E32 series are HERE!

  23. #23
    Join Date
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    11/88 E32 750iL+98 E36M3
    Sensor Specifications
    1990 735 SERIES
    RPM Reference Position Sensor Resistance 490-550 Ohm
    Intake Air Temperature Sensor Resistance
    Temperature(℃)..... Ohm
    -10............... 8260-10560
    17 -23............. 2200-2700
    47-53................ 760-910

    Water Temperature Sensor Resistance
    Temperature(℃)............. Ohm
    -10.............................. 8260-10560
    17 -23............................ 2200-2700
    47-53................................ 760-910

    Cylinder Identification Sensor Resistance
    Resistance 0.2-1.0 Kohm

    Air Flow Sensor Voltage
    (Idle To Wide Open Throttle ) Voltage 1.0-4.5V

    O2 Sensor Voltage
    Condition V
    Lean 0.25
    Rich 0.85
    Last edited by shogun; 03-05-2022 at 06:18 PM.
    Shogun tricks and tips for the E32 series are HERE!

  24. #24
    Join Date
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    11/88 E32 750iL+98 E36M3
    Especially for 735 and 750 with EML and fly by wire throttle valves. Throttle valve cleaning is absolutely necessary after so many years in use. Instead buying new ones for > $1000 you can clean them for zero $.
    Here a good write up by MWrench:
    DK Motor clean up
    When first tested, I applied 12 volts, current limited to 2.5 amp thru the motors of the DK Pin 3 and pin 5. One DK opened the throttle plate but the other did not. I then measured the resistance between pins 6-8, 6-7 and 1-8 in both conditions of closed and open throttle. The units were in spec but quite a bit different between the two.
    I then opened up the DK that did not move when 12 volts was applied to pins 3-5. this is what I found.
    One brush was stuck out and would not make contact with the commutator.
    This is what the commutator looked like when removed.
    One thing that caught my eye was the condition of the feedback resistor set up. This is part of the DK that tells the EML how far open or what the position of the butterfly valve is. There is also a resistance that opens up at about 10 degrees of movement of the throttle plate. (between pins 1-7).
    The black stripes are resistance material that is deposited on a substraight. Attached to the throttle boy shaft is a set of wipers that make contact with the resistance material. The wiper position is preset at the factory. As the throttle plate moves, the wipers also move along the resistance material and the resistance value changes.
    Major concern on this DK set is the amount of wear on the resistance material. When the wipers wear thru the resistance material, the resistance readings sent back to the EML will not longer be correct or may fluctuate wildly during throttle plate movement. This certainly would set off the EML light and may initiate “limp home” mode.
    See pics in DKMotorcleanup http://www.mwrench.com/Whitepapers/

    A bad DK can look like this, before cleaning http://s71.photobucket.com/user/shog...tml?sort=4&o=6

    Cleaning procedure http://www.e38.org/e32/throttles/BMWThrottles.htm

    Test details are on my website under reference data

    Bad ignition coils http://produkte.bilder-speicher.de/1...il-defect.html http://produkte.bilder-speicher.de/1...il-defect.html



    12 V car batteries
    Car 12 V batteries are really 12.6 V with a accurate meter measured at the battery post.
    State of Charge..Specific Gravity..Voltage
    .............................................12V
    100%................ 1.265..........12.7V
    75%................. 1.225.......... 12.4V
    50%................. 1.190.......... 12.2V
    25%................. 1.155.......... 12.0V
    Discharged.......... 1.120.........11.9V

    With unlocked OBC,TEST-NR. 09 UB: xx.x V (battery voltage)

    Useful for battery condition tests. Engine not running value should be above 12V....cranking voltage should not drop below 9V. When fully charged the voltage should show > 14V

    With engine running it fluctuates usually between aprox 12.8 - 13,90 on my 750.

    Start the car. Connect the meter at the jumper terminal under the hood and measure maybe around 14.0vDC, then go to the + terminal on the battery itself and repeat. If you have strong charging voltage at the jumper terminal but not at the battery terminal, then you have a loose connection between the post under the hood and the battery post in the trunk. If you have strong voltage at the battery then you should also have strong voltage under the hood, and you have a weak battery that cannot take a charge anymore. Also check fusible links near battery.

    If you have strong voltage at the battery, then you are either not driving the car long enough to charge the battery, or the battery is done. The alternator makes 14.1vDC (based on my Hella voltage regulator), give or take about 1/2 volt when it is working. You can check for this regardless of the status of the battery. All you need to do is get the car running and you can check the alternator output.

    Also important is the cable between alternator and B+ pole, they get very bad over years and even fires started, see repair/replacement on my website. Since I replaced the alternator cable years ago, I get more voltage at B+ and on OBC.

    Once upon the time R. Trochelmann of performing imports told me when discussing about EML systems: "Low voltage will set EML only if it drops below 11V for more than 90sec. Low voltage will also cause problems with the IKHA (heater/ac), memory for seats/steering and transmission will go into limp mode. Just for clarification: I am a 20 year BMW Master with 3 PhD's from Germany in Engineering and I know these systems better than almost anyone. I did 12 years of R&D on these system for a manufacturer in Germany, so I am not some "Key Board" mechanic or read some crap on the internet. Ronald Trochelmann"

    Car Battery FAQ http://www.batteryfaq.org/
    Last edited by shogun; 03-15-2016 at 03:36 AM.
    Shogun tricks and tips for the E32 series are HERE!

  25. #25
    Join Date
    Jan 2005
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    11/88 E32 750iL+98 E36M3
    Another case, E32 750 Alpina B12 with M1.7 Motronic, the newer one with Bosch end # 352: My wrenching buddy complained about rough idle, sometimes as if not all 12 cylinders were working. End result of checking and solving:
    one of the spark plugs was bad were the donuts are connected to the ignition cable. That is cylinder 6 and 12. No spark sometimes and also the ignition wire was fouled, similar to this one who then installed my ignition wires
    http://www.bimmerboard.com/forums/posts/767718/
    We replaced the ignition wire from my stock parts for this cylinder only and the spark plug, runs well again.

    Oxygen sensor - thermoshock, M70 engine - info: E32, E31 M70, Date 01/1997 - Rough or hunting idling and/or clutch judder when driving. "Check engine" lamp comes on in US vehicles.

    Cause: An increasing amount of water collects in the exhaust system due to unfavourable driving conditions such as frequent stop-and-go driving, long periods of idling and a lot of short-distance driving. This water builds up through e.g.:
    separation of the water content in the fuel during cold start as a product of the combustion process through condensing of the air moisture in the exhaust as the exhaust system cools down.
    The ceramic sensor body that is heated immediately after the engine is started and quickly achieves a high temperature is damaged by this cold condensate (thermoshock).
    The following fault codes may be stored in the DME fault memory:
    DME M1.2: "10" - Oxygen-sensor control and/or "28" - Oxygen sensor
    DME M1.7: "70" - Oxygen sensor and/or "201" - Oxygen-sensor control
    Affected vehicles: E31, E32 with M70 Manufacturing period: from start of series production up to October 1994.
    Remedy:
    If the oxygen sensor malfunctions repeatedly, not only the oxygen sensors must be replaced, but a Service solution must be retrofitted that has the following effect: delay of oxygen-sensor heating after the engine is started, depending on the engine temperature and the engine load.
    Procedure:
    1. Replace the oxygen sensors and clear the DME fault memory.
    2. Retrofit the Service solution consisting of an "oxygen-sensor-heater relay" and Service wiring harness.
    All the details here http://www.bimmerforums.com/forum/sh...ock-M70-engine
    Shogun tricks and tips for the E32 series are HERE!

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