Stumbles/shuts off on cold starts, can't figure it out

[91 318is]

No miracles promised...

BMW issued a service bulletin 13 03 91 (3290) dated July 1991 for M42s produced between 2/90 and 12/90, last seven of serial #s EE65001-72808 for the 318is and EJ00000 - EJ05097 for the 318i.

Dealer has to run a check through their Dealer Communication System to see if a particular car gets the fix or not.

The next two paragraphs are verbatim quotes:

Situation: Due to an occasional impairment of the signal between the air flow meter potentiometer and the DME control unit, the engine idle may dip below specification at times causing a possible rough idle condition.

Correction: Adapter harness (P/N 13 61 1 734 516) must be installed on all affected vehicles between the engine wiring harness and the air flow meter. The adapter harness, which incorporates and impedance converter, filters and amplifies the signal from the air flow meter to the DME control unit.

Hmmm, I'm gonna have to call on the dealer on this one to see what they say.  That's what I've been saying the whole time, it almost acts like it loses signal from a sensor, stumbles, and then picks the signal back up and keeps going.


Also, thought the condition was getting better?  WRONG.  Started it up yesterday after it was sitting for a few days, as it was running, I was moving another car in the driveway and the car stumbled again.........again..............and again.  It's never stumbled repeatedly.

So obviously everything I've put on it has done nothing.  Hopefully this service bulletin will give me some higher hopes.

[91 318is]

No miracles promised...

BMW issued a service bulletin 13 03 91 (3290) dated July 1991 for M42s produced between 2/90 and 12/90, last seven of serial #s EE65001-72808 for the 318is and EJ00000 - EJ05097 for the 318i.

Dealer has to run a check through their Dealer Communication System to see if a particular car gets the fix or not.

The next two paragraphs are verbatim quotes:

Situation: Due to an occasional impairment of the signal between the air flow meter potentiometer and the DME control unit, the engine idle may dip below specification at times causing a possible rough idle condition.

Correction: Adapter harness (P/N 13 61 1 734 516) must be installed on all affected vehicles between the engine wiring harness and the air flow meter. The adapter harness, which incorporates and impedance converter, filters and amplifies the signal from the air flow meter to the DME control unit.

Just checked my mfg date and VIN and they both fall under the service bulletin.  I'm gonna call my dealer now and see what they say.

[91 318is]

Called and service had to take my info down because they're short-handed today.  Haven't heard back from them yet but I did talk to parts about that adapter harness part # and they said the number is no good.

[romeomike]

Called and service had to take my info down because they're short-handed today.  Haven't heard back from them yet but I did talk to parts about that adapter harness part # and they said the number is no good.

Sorry I was off one on the part # re-read the bulletin and the correct number is (P/N 13 62 1 734 516).

[91 318is]

Sorry I was off one on the part # re-read the bulletin and the correct number is (P/N 13 62 1 734 516).

Thanks, I'll call monday and see what they say.

[romeomike]

Did a quick look at pelicanparts.com for the adapter cable 13 62 1 734 516, and it's $246.50.

[DesktopDave]

Aha!  I wondered what that was...I pulled it out of mine to fix an AFM code!  I'll post a pic of this ridiculous little piece of cable for you:


Not worth $250 IMHO.  I never figured there would be a pack of resistors there, but when I peeled back the cover, there it was.

I'll let you borrow it for troubleshooting if the BMW dealer won't help out.

[91 318is]

Did a quick look at pelicanparts.com for the adapter cable 13 62 1 734 516, and it's $246.50.

GOOD GOD!

Aha!  I wondered what that was...I pulled it out of mine to fix an AFM code!  I'll post a pic of this ridiculous little piece of cable for you:


Not worth $250 IMHO.  I never figured there would be a pack of resistors there, but when I peeled back the cover, there it was.

I'll let you borrow it for troubleshooting if the BMW dealer won't help out.

So you took the adapter out because it was giving you issues?  Wonder if the resistors went bad?  Are you still using it?  

I would REALLY appreciate it if you would let me try it out.  I would hate to drop $250 for an 1' harness that won't fix it.

[91 318is]

Found out that my car had it on already, removed it and drove it home from work, seemed to idle smoother, no stumble either.  I probably should disconnect the batter to reset the DME to make sure it's good.  Only bad thing is now I found a bad leak from my steering rack, so it parked until I can swap that out.

I'll update in a few weeks hopefully.

[romeomike]

I don't know if this will be the kissing cousin to the catalytic converter provision plug (hot start issue), as in disconnect things and performance improves.

Now leaking steering racks, that's more typical, albeit not much fun either.

Good luck sorting it out.

[91 318is]

Got the new rack on, but I still have my stumble, seems to do when it's cold, once it warms up, it doesn't do it much at all.  

I have noticed that the idle is A LOT smoother without the harness adapter in.  Even when the A/C's on, the car use to idle rougher, now it's better.

Next step is to replace the crank and cam sensor, we'll see what happens there.

I'm tired of troubleshooting, just gonna start throwing parts at it.

[DesktopDave]

+1 on the harness.  Mine ran when I pulled it, though it was probably the CPS too.

[///m42 sport]

Thanks for the updates guys, as stated before I had similar issue with stumbling in subzero temps.  Sortof forgot about it once the weather warmed up.  I'll check to see if I have the harness in mine.

In the meantime, I ordered a new ICV.  Will see what happens once the winter starts in Michigan.

[91 318is]

I know this my OLD thread, but I never gave an update and I thought I did so here you go:

After troubleshooting basically blind, I read on another site that a M42 owner was having a similar problem and found out it was ignition coil failing.  So I was gonna try the COP kit, but ended up getting a used set of coils just to make sure that was the problem.  Swapped them out and haven't had a problem since.  I don't know how I would have found it if I didn't have talked to the other owner.

Hope this helps future troubleshooting!