1982 633CSI out of storage ... won't fire up

[schwarz633]

My 1982 633CSI has been in heated dry storage for about 5 years. I put a new battery in it today and have got it spinning over, but no fire. I'm in SE Wisconsin so it's got the crap gas in it. I didn't treat the gas prior to storing. It was running fine when it went into storage. After cranking it for a while, I did notice some gas leaking back by the tank, so I'm pretty sure that the fuel pump is working. As I recall there's some hose clamps back there that I've had to tighten post-storage in the past. Any suggestions? Thanks.

[Seeker]

shoot a bit of starting fluid in it and see if it fires?

sitting that long with old gas, the injectors could all be clogged up bad.

[Taylor Marshall]

I think you already answered your own question:
" I didn't treat the gas prior to storing. It was running fine when it went into storage."

I believe the old gas has jelled and will need to be completely drained and replaced with fresh fuel. You may have fouled both your fuel filter and your injectors now in trying to start it with gunky petrol.

[CW6er]

Draining the tank and getting fresh fuel is a good place to start.

Are you getting a spark?

Pull a plug wire and get an extra spark plug (or use a spark tester, these can be had from an auto parts store) and plug it in. Position the plug so that the metal shell is grounded and try to start the car. Watch the plug to see if you are getting a spark.

If no spark, I have a list of things to check.

[schwarz633]

OK, I found a bad fuel pump relay. The one that hangs upside down just in front of the fusebox. It's totally corroded inside. It's a 12V 30A 4 prong relay, no diode.

OK, this is starting to get uber frustrating. I picked up a relay from O'Reilly (Dorman 84601) and when I was confirming the pin-out I found out that two of the terminals were reversed from the original relay. One coil terminal and one contact terminal are swapped. I'm an electrical controls engineer, so it's not like I don't know something about relays. Not to be defeated, I made up some jumper wires with male and female 1/4" push-on terminals so I could connect it properly. Still no go. I'm not getting any spark and I don't think that the fuel pump(s) are running either.

I have the spiral bound "Electrical Troubleshooting 630/633CSI" manual (1977-1982) and things just aren't matching up between the car and the schematics. I also just discovered two 25A fuses (wired in parallel?) on the inner fender just above the battery. They're the euro-style ceramic type with a thumbscrew cover, so I don't think that they're anything but original from the factory. These fuses don't show up anywhere on the schematics. The power to the fuel pump relay contact (terminal 30) appears to come from these fuses and is always on.

The fuel pump relay and purge valve relay locations are also reversed from the diagram in the manual. In the car the fuel pump relay is in front of the fuse box (outside) and the purge valve relay is on the engine side of the fuse box (outside), towards the front of the car. I'm pretty sure that I've identified these correctly, as the fuel pump relay has large gauge wires and the purge valve relay has small gauge wires.

I also removed and tested the main relay in the glove box and confirmed that there was power to it's coil wires when the key was on.

I also pumped all of the old gas out of the tank and put in 10 gallons of fresh.

I've given up for today, but hope to spend some more time on it tomorrow.

I think I will begin with removing the ECU connector and seeing if it's getting any power. Maybe my ECU is bad, as it doesn't seem to be turning on the fuel pump relay.

Any suggestions will be appreciated.

[Bentsdl]

Hm, are you sure you have a E12 based L-jetronic six? Because that could explain why the ETM is not matching up. The one you have is for the earlier sixes from 77-82. But 82 was the changing point, so your car could actually be E28 based car too. And then there are some cars that have mixed pre and post 82 electronics.
Does your engine look like this:


If it does, you can check the fuel pump/relay by pushing the afm flapper open while you have the ignition key at second contact position. If you open the flapper the relay should click and the fuel pump run.
I would not mes with the ecu before you have conformed that you have fuel on the injectors.

If you engine looks like this:


Then you have a E28 based motronic car and you ETM is useless then. I don't know much about the later electronics, but I'm sure someone can help you.

[schwarz633]

I'm not near the car right now but from memory I'd say the engine bay looks more like the bottom picture. I know my distributor cap is pointing forwards and the intake manifold has the horizontal runners. My car has the old style interior and I've always considered it to be E12 based. Do you think that an ETM covering 1983 would be more accurate in the area of the engine electronics?

[Bentsdl]

I'm not near the car right now but from memory I'd say the engine bay looks more like the bottom picture. I know my distributor cap is pointing forwards and the intake manifold has the horizontal runners. My car has the old style interior and I've always considered it to be E12 based. Do you think that an ETM covering 1983 would be more accurate in the area of the engine electronics?

Ok, you probably have a something like Bert Poliakoff, what he calls a red-headed-stepchild. A weird changeover car/engine with both pre and post components. I believe Bert has a M90 with the later style intake manifold that you have too with the horizontal runners and a motronic ecu. But with the earlier high impedance injectors. His car is a 81, so you have a good change that your (82) engine is motronic too, and most likely not covered in your etm. The rest of the car is probably normal E12 based.

Unfortunately I don't know much about the motronic engine, but what I would do to check if you have fuel pressure is just disconnect the tube that goes to the cold-start valve (basically a 7th injector) and put a cup under it and start the engine. If you get no fuel there's definitely something wrong with the relays or fuel pump. Int that case work you way from the relays to the pump with a voltmeter and see where the problem is.

[schwarz633]

I pulled and tested all of the relays I could find, all good with the exception of the one I previously thought was the fuel pump relay. Still not sure what that one is for, but I replaced it with the horn relay. I'm pretty sure I identified the fuel pump relay based on the wire colors. It's located on the engine side of the fuse box (external) and has a rectangular silver relay type device piggybacked on it.

This silver device is mysterious. It has four prongs but in a different configuration from the 12V 30A relays. I can't read anything across any of the terminals with an ohmmeter. It doesn't have any markings on it. It has what appears to be a green shielded wire going to it. The core and shield are each connected to different terminals. This shielded cable and a brown wire run over to the AFM where they tee off into a male and female AFM connector. This "tee" is plugged in between the AFM and the original AFM connector. It looks to be some sort of a factory field fix-it kit to me. That cable was poorly installed (by a dealer, how could that be?) and was hanging down in a loop behind the head where is seems to be rather stiff and probably oil soaked. The installation of the silver box also has involved tapping into some of the wiring on the fuel pump relay and what I suspect is the purge valve relay (not sure though). There was an inline diode in this mess that I discovered was open circuit so I replaced it with a diode and some push on terminals.

I loosened the rear hose on the fuel rail and gas started to spray out, so it seems like I've got pressure.

I found the ETMs for a 1982 528e and a 1983 633CSI on the internet, but they only seem to add to the confusion. I really need a schematic for exactly what I've got to work my way though this.

[Captain Bavaria]

Two most common early motron faults I can think of:
Check the wire running into the AFM. Is it fully seated? Motrons will not run without it connected.
Additionally, the reference sensor must be sending the signal of the crankshaft's angle for the car to start. It is connected to the bellhousing and the electrical connection is up on the engine brace closest to the cabin- it's the gray connector. To test it- just disconnect it and nab the resistance of two pins right next to eachother- two should show 100k+, and the other two should be round 960 (give or take 96). Anything over or under that ohmage (is that even a word?!) means it's toast.

[schwarz633]

Pictures of some of the things mentioned in my previous post:

http://picasaweb.google.com/10852341...eat=directlink

How do you get the sensor connectors apart with f'ing them up? It looks like there's a thin steel wire that locks in under a plastic tab on each end. I tried pushing the plastic tab in but I didn't want to force it. They appear to be the same kind of connectors as on the injectors, but I don't know how to get them apart either.

[Captain Bavaria]

Pictures of some of the things mentioned in my previous post:

http://picasaweb.google.com/10852341...eat=directlink

How do you get the sensor connectors apart with f'ing them up? It looks like there's a thin steel wire that locks in under a plastic tab on each end. I tried pushing the plastic tab in but I didn't want to force it. They appear to be the same kind of connectors as on the injectors, but I don't know how to get them apart either.

4lb sledge. Or I get them by getting a small screw driver up under one of the ends of that metal wire, and prying it directly away from the body of the connection. Then, with that metal clip undone on one side, you should easily be able to continue to pry around it. Once that thin metal clip is off, the connector will pull off with barely any force.

[CW6er]

Something is definitely screwy here, we need to find out exactly what car you have. It sounds like you have the Motronic engine, but which chassis? And is it US spec. or Euro Spec.? Enter your VIN number in this Decoder as a start:

An online Vin Decoder:
http://www.bmw-z1.com/VIN/VINdecode-e.cgi

[EDIT:] Ok, it shows your car as a US spec 633 with a build date of 12/81, Manual, and no Cat., so it is an e12 based Chassis, but when I looked it up in the RealOEM and it shows that the engines were Motronic from 9/81 which is before the Chassis change at 6/82. So it looks like you may have to use your 77' to 82' ETM for the chassis and the '83 ETM for the engine and figure out how they merge.

_____________________________

OK, I found a bad fuel pump relay. The one that hangs upside down just in front of the fusebox. It's totally corroded inside. It's a 12V 30A 4 prong relay, no diode.

Should have a shunt resistor or diode, it is controlled by the solid-state ECU. (See the "Low down on relays" at the end for sources.)

OK, this is starting to get uber frustrating. I picked up a relay from O'Reilly (Dorman 84601) and when I was confirming the pin-out I found out that two of the terminals were reversed from the original relay. One coil terminal and one contact terminal are swapped. I'm an electrical controls engineer, so it's not like I don't know something about relays. Not to be defeated, I made up some jumper wires with male and female 1/4" push-on terminals so I could connect it properly. Still no go. I'm not getting any spark and I don't think that the fuel pump(s) are running either.

I have the spiral bound "Electrical Troubleshooting 630/633CSI" manual (1977-1982) and things just aren't matching up between the car and the schematics. I also just discovered two 25A fuses (wired in parallel?) on the inner fender just above the battery. They're the euro-style ceramic type with a thumbscrew cover, so I don't think that they're anything but original from the factory. These fuses don't show up anywhere on the schematics. The power to the fuel pump relay contact (terminal 30) appears to come from these fuses and is always on.

Which Main fuse box do you have, the one with the blade fuses (bottom pic), or the one with the ceramic type (top pic)?

My '87, with the later "blade fuse" fuse box, still has the 2 ceramic type fuses in a box as you describe, but they are Aux fuses for aftermarket accessories. Normally the power to pin 30 on the relay is a wire directly from the battery, the pump itself is fuse 11. I wonder if the relay you are talking about is an aftermarket alarm or a jury rig for upgraded head lights or a jury rig for the Aux Fan?

[EDIT:] These two fuses are for the Electric Aux Fan on an e12 based chassis. If you look on your early ETM, find the aux fan and trace back, it should show the fuses.

I also removed and tested the main relay in the glove box and confirmed that there was power to it's coil wires when the key was on.

Only the M6/M635 have the Main Relays inside, above the glove box ?!? The Main relay is normally located on the outside of the fuse box with the fuel pump relay. I'm beginning to wonder if you don't have an early car with a later Motronic engine swapped in??

[EDIT:] Can you confirm you have identified the 5 prong Main Relay?

I think I will begin with removing the ECU connector and seeing if it's getting any power. Maybe my ECU is bad, as it doesn't seem to be turning on the fuel pump relay.

The Fuel pump only comes on when the engine is cranking or running (safety feature).

_______________________________

OK, now that I am throughly confused, here a couple of cut and past guides I made that may be of help (If you do indeed have the Motronic in a US spec car):

Break down of components needed to get spark to the engine:
Ignition Switch, OBC Relay, Main Relay, Coil, Reference Sensor, ECU
____________

First check for spark:

Pull a plug wire and get an extra spark plug* and plug it in. Position the plug so that the metal shell is grounded and try to start the car. Watch the plug to see if you are getting a spark. If you are getting spark, skip to the next section to check for fuel.

If you are not getting spark at the plug, test again at the coil tower. if you get spark at the coil but not the spark plug, check the Distributor Cap and Rotor.

(* or use a spark tester, these can be had from an auto parts store. You may also need an extra plug wire to plug in and test at the coil tower.)

If no spark from either the Coil or Spark Plug:

Checking the ignition Switch and Coil:

• Check, with the key on, for voltage at terminal 15 (+) on the coil. If no voltage, the ignition switch or wires to it may be bad. Wiggle the ignition switch to see if it is intermittent**.
  
  Check the resistance between Terminals 1 (-) and 15 (+), of the coil. It should be 0.50 Ohms. The resistance between terminal 15 (+) and the high tension center tower should be 6000 Ohms. Replace the coil if it has higher readings.

Checking the OBC Relay:

• Next, pull the Main relay and with the key on, check for voltage at pin 86 in the relay holder (the numbers are molded into the bottom of the relay).
  
  If there is no voltage at pin 86, check the OBC relay box under the driver's side kick panel, by jumping the two green wires (pins 3 & 4) in connector C2. If there is no voltage at pin 3 of C2, the ignition switch may be bad (both terminal 15 on the coil and pin 3 of C2 are powered from pin 15 of the ignition switch).
  
  If voltage is present at pin 86: It is easiest to just swap in a new/good main relay and then skip to the check for the Speed and Reference Sensor below, otherwise check the main relay as in the next steps.

Checking the Main Relay:

• Check the circuit diagram on the side of the Main Relay to see if it has two separate contacts for the output pins 87 and 87b or if it just has one contact going to two pin 87's. Plug the Main relay back in.
  
  If there is just the one contact: With the key on and the Main relay plugged back in, check for voltage at the RD/WH wire in an fuel injector plug (or use a "noid" light on the injector plug).
  
  If there are two contacts: With the key on, check for voltage at BOTH terminals 87 and 87b of the Main relay. (You have to wrap a wire around each pin and plug the relay back in and test for voltage at each wire. Don't short between the pins!! One terminal can be good, suppling power to the fuel pump, and the other bad, not suppling power to the ECU, or vice versa.
  
  • Alternately, to check both relay contacts and the Start Input: With the key on, check for voltage at Pin 4 (Start Input) and Pin 35 in the ECU harness plug, and at the RD/WH wire in an fuel injector plug (or use a "noid" light on the injector plug).
  
  
  If there is no voltage in the tests above: replace the Main Relay. As stated, it might be easier to just replace the Main relay out of hand in the first place, instead of doing the testing. It is also a good idea to keep a spare Main relay in the trunk Tool Kit and just replace it (and the Fuel Pump Relay) out of hand if the car stops out on the road.

Checking the Speed and Reference Sensors:

• Check the plugs to the sensors first, the plastic can get brittle with age and they can crack around the wire locking bail leaving them loose. Then check their resistance as below (won't hurt to check them both hot and cold if the car's hard starting is temperature sensitive):

** (To start with a bad ignition switch: run a jumper wire direct from the battery to term 15 (+) of the coil and jump pins 11 and 14 in the diagnostic plug to engage the starter.)

________________________________


________________________________

Here is the lowdown on the Relays :

(Updated 01/01/10)

The main relay is a 5 prong relay with 2 terminal 87's. The OEM's have 2 separate internal contacts with a pin 87 and 87b. In these, one terminal could test good and power the fuel pump relay and the injectors, but the other could be bad and not power the ECU. Many of the replacements just have the one internal contact and two pin outs, both labeled 87. Do not confuse the Main relay with the 5 prong Change-over relay (High-Beam, and Blower Select) with pins 87 and 87a (see below)

Main Relay, 5 prong, 3 Main Choices:

OEM BMW (12 63 1 708 646 - 25x25mm case, Double Diode) - $33- Special order from the Dealer, Pelican or BavAuto (OEM $24 from SteveHaygood.com) These units have potting compound to seal the bottom (First one to the left in the photo below).

Audi-VW /Stribel (61361729004* - Larger white case, with ears, difficult to fit under rubber boot, Double Diode) Potted bottom like BMW OEM - $14.87 (AutoHaus) (White middle one in the photo below). (There is a $13.95 look-a-like at BavAuto & Pelican, but it does not have the potted, sealed bottom. might as well buy the cheaper Bosch below that fits better)

Bosch replacement (0 332 014 135 - 25x25mm case, Resistor) - $11.33 (AutoHaus) This unit is unsealed, like the other relays inside the fuse box and is the 25x25mm metal can that fits under the rubber boot. It would be protected in an M6 glove box. (Last one to the right in the photo below). (Due to Bosch supercession, replacement units may now have black plastic housing, version 0 332 019 109, instead of this metal version. )
_______________ (also

Hella (12631708646 - Black case, No ears, Double Diode) Don't know if unit is sealed or not - $13.08 AutoHaus (not shown)

There is also the Bosch (0 332 014 112) which will work in a pinch, but it does not have a suppression resistor/diode across the coil, so it will wear the ignition key contacts faster - $11 at AutoHaus. (This info may be wrong, AutoHaus shows this relay with a diode on terminal 86)

Fuel pump, O2 and other 4 prong Relays**:

( K1, K2, (K4- '83-'87), K5, K6, K7, K8, K9, and Start Relay. The OEM Green ones - 61 31 1 373 585/ended - 61 31 1 378 297, no longer seem to be available):
Bosch 0 332 014 406 - $9.95 (BavAuto) This is the 25x25mm metal can relay that fits under the rubber boot on the outside of the fuse box, and is the same size as the original green relays

There is also the cheaper ($7 AutoHaus), and easier to find Bosch 0 332 019 456 - (Same size and style with ears as the White one below, but Orange case) - it is a slightly larger case then the OEM Green ones, with several lugs sticking out that will just barley fit in the fuse box and work, but looks out of place with the other stock relays. This wouldn't be a problem under the dash in an M6.



High-Beam Headlamp (K3), and Blower Select relay:
5 prong change over relay (output changes between pins 87 and 87a as relay operates) - Bosch 0 332 204 401 (Do not confuse it with the 5 prong Main Relay, See above)

The photo shows the same 3 Main relays, the OEM BMW, the Audi-VW /Stribel, and the Bosch 135, turned to show all of the sides:
_______________



______________________________
For a more comprehensive listing of the relays, and why the relays need suppression resistor/diodes, the BCG Tech library: http://www.normgrills.net/bcg/Electr...ectrical-47857

** Cross References (unverified) for the Bosch 0 332 014 406 = Valvar /230006; - Hella /4 RA 003 205 00; - Stribel /SR 9875; - Wehrle Kirchzarten /21 201 12 V
* (This number at Pelican brings up a BMW Mototronic 5 prong for the e34 5 Series and a list of 3 Series it is used in, but I don't believe it is potted, $18.25).

[schwarz633]

I have located the auxiliary fan fuses (2 x 25A) on the 1982 ETM. So that confirms that the bad relay that I found initially is the normal speed relay, not the fuel pump relay as I had initially thought. The high speed relay must be the one that I've been eyeballing screwed to the radiator support down low just in front of battery. I was kind of working around that one, as I need to remove the battery to gain access.

As far as the main relay, I'm not where the car is right now, but I did remove and test the relay above the glove box, but right now I can't remember if it was 5 prong or not.

I'll start looking a little closer at the 1983 ETM and see if I can get things sorted out.

Keep the ideas coming. Thanks.

[CW6er]

This silver device is mysterious. It has four prongs but in a different configuration from the 12V 30A relays. I can't read anything across any of the terminals with an ohmmeter. It doesn't have any markings on it. It has what appears to be a green shielded wire going to it. The core and shield are each connected to different terminals. This shielded cable and a brown wire run over to the AFM where they tee off into a male and female AFM connector. This "tee" is plugged in between the AFM and the original AFM connector. It looks to be some sort of a factory field fix-it kit to me. That cable was poorly installed (by a dealer, how could that be?) and was hanging down in a loop behind the head where is seems to be rather stiff and probably oil soaked. The installation of the silver box also has involved tapping into some of the wiring on the fuel pump relay and what I suspect is the purge valve relay (not sure though). There was an inline diode in this mess that I discovered was open circuit so I replaced it with a diode and some push on terminals.

Finally found the answer, I thought I saw this same thing before. It is a factory service work-a-round (scroll down to his second diagram, it is more compete):
http://bigcoupe.com/phpBB2/viewtopic.php?p=59691#59691

I'm not 100% sure this is the Service Letter, but may be of interest:
http://bigcoupe.com/phpBB2/viewtopic.php?t=10290&

Here is a page of resources, Online Factory Manual, ETM's, Parts Catalogs, Parts Suppliers, etc., Bookmark them:
http://bigcoupe.com/phpBB2/viewtopic.php?t=10410

[schwarz633]

Thanks for the links, they are definitely helpful. I spent some time last night making a spreadsheet of all the connections to the Motronic MCU using my 1982 ETM. Now that I've become more familiar with it, I starting to think that it is correct for the car. I was initially thrown off by mis-identifying some relays, not finding the auxiliary fan fuses on the diagram, and of course the mysterious silver "relay". Hopefully I'll get some time this week to take another stab at it.

[CW6er]

'm curious about this '82 ETM you have, is it organized like the '83, with a system stating at the power source and then tracing through the components affecting the system and then finally to ground.

Or is it the more traditional layout with the headlights at the front with the wiring flowing back through all of the components until the taillights are reached?
__________

Another thing to look at, do the previous years ('81and older), show the 12 pin "Combined Relay" of the L-Jet system while the '82 shows a separate Main and Fuel relay of the Motronic?

[Bert Poliakoff]

My 81 Euro, has separate main and fuel relays, located on the engine side of the exterior of the fuse box. and also uses low impedance injectors. This is as original from the factory.

[schwarz633]

My printed 1977-1982 630/633CSi ETM (P/N 89 89 1 000 110) has the same layout as the 1983 633CSi pdf version that I have, but the schematics in the printed version are 3 feet long when you unfold them from the book. Using it automatically generates a multitude of 4 letter words.

Yes, the schematic for 1981 shows a combined relay with 12 connections, while the 1982 schematic shows separate fuel and main relays along with the Motronic MCU.

I spent some time today documenting the various relays, and there is certainly the potential of screwing things up if you're not careful. Only the Germans could make things this complicated.

My fuel pump relay (1 373 912.3 black plastic) and main relay (Bosch 0332014112 metal) are both 5 prong.

The fuel pump relay appears to have double contacts with the terminals marked 87 & 87b. It also has what I think may be a resistor in parallel with the coil. The position of terminals 30 & 86 are in what is called a Non-ISO configuration.

The main relay has a single contact connected to double terminals 87 & 87. It has a diode in series with the coil. The position of terminals 30 & 86 are in what is called a ISO configuration.

In other words, terminals 30 & 86 are reversed between the two relays, but the relays are physically interchangeable. I can't think that getting them mixed up would end well.

I had initially considered having the car towed to someone that could get it running, but I have pretty much resolved myself to the fact that I am probably the most qualified person available. I've taken it on as a personal challenge.

[tlister67]

I am coming into this thread late as I have been on travel. I have the same car as yours, 82 633 with everything e12 but a motronic engine. It will drive you crazy until you figure out what systems are in your car from each era. On my way to work but tonight I'll try to go through this thread and see what I can provide. If you have any specific questions or need pics let me know.

I have the same elongated relay going to the AFM which I have not really figured out yet. It is ganged to the fuel pump relay on mine just in front of the wire loom. The diode looks to be replaced and I remember one being there in mine.

The low speed fan is hanging on the fuse box. The high speed relay is fed by those 25A fuses on the fender in you pic. The relay is in front of the battery in a bad spot for corrosion, clean those contacts and test relay. It feeds directly to the fan. To test the fan get under the lower right of the radiator and look for green wires going into a bronze fitting. There are two switches for low and high speed fan speed. It the relays and (and resistor) are working then each speed should operate as you short them with a wire. Car will run with the fan circuit disabled but you should check it out.

[schwarz633]

OK ... back at it. Power on coil terminal #15. Coil ohms out good. No spark at coil. Fuel pump relay is energizing. Reference sensor (gray) 167 ohms between 1&2 ... low but probably OK. Speed sensor (black) infinity ohms between 1&2 ... open circuit. Peeled back the rubber hood on the connector and everything looks OK. Jiggled cable while reading ohms with meter .. nothing. How could this sensor have gone open circuit while just sitting?

These sensor cables run into an enclosed wiring harness that goes through the firewall under that ribbed cover just in front of the windshield. It looks like the replacement sensors already have a connector. How do you deal with that? Do I need to lift the car to replace this sensor?

Is the Bosch 0261210002 ($51.26 @AutohausAZ) a suitable replacement?

Thanks.

Semi-false alarm. I was taking the ohm readings on the cables that go to the MCU, not the sensors. Reference sensor (gray) ~1000 ohms between 1&2. However, the speed sensor (black) is still infinity ohms (open circuit) between terminals 1&2. Plus, I have determined where the sensors are located, and it looks like I may be able to access them from the top.

[CW6er]

The speed and Reference sensors are interchangeable, they are the same part number, but their position is what counts, don't mix them up. To match the Gray Ref sensor plug to the sensor lead that goes to the bell housing position stamped "B", the factory has a gray or white "ring" on the sensor cable end mounted in the bracket. When you replace it, use a white "zip tie" to mark it instead. The black Speed sensor goes to the bell housing position marked "D".


Yes, that is it, BMW part No. 12141708619. The other one is the pulse sensor at the front of the engine and is only used by the BMW diagnostic equipment, and has nothing to do with the running of the engine, it can even be removed if desired. (In '88 they removed the bell housing sensors and used the front sensor with a pickup on an ignition wire for the Motronic 1.3).

[schwarz633]

Well, I've got them both out now and they are both marked 0261210002, so I guess I'll order them from AutohausAZ, that seems to be the best price I could find. Thinking I could get them out from the top was a flawed plan, had to put car on a lift.

Are you sure about not needing the reference sensor? It would seem that the MCU would need that pulse (assuming 3 pulses per flywheel revolution) as a basis to calculate when to fire the ignition coil. Something has to synchronize the spark with the rotation of the engine, and it certainly isn't the distributor, it just directs the spark to the proper cylinder.

The speed sensor is just generating a high frequency pulse train that doesn't provide any reference to where the crankshaft is in it's 360 degree rotation.

[CW6er]

No, you do need the Reference sensor, as well as the Speed sensor in the bell housing. The Speed sensor reads the flywheel teeth and the Ref reads a single pin in the flywheel to provide that ref point.

It is the pulse sensor at the front of the engine at the crank dampener that I was saying you don't need. The ETM clearly shows that it is not hooked up to anything except the diagnostic plug and many engines are happily chugging along with this sensor unplugged.

[schwarz633]

Sorry, I misread your post. I thought your reference to "sensor at the front of the engine" was for the front one of the two in the bell housing. I'll have to take a look and see if I even have that third sensor in the front.