e32 735i '91 engine starts, sputters, revs up + down between 1000 + 2000 RPM - solved

[Kibokojoe]

stumped big time>>>>>
son has a e32 735i 1991 engine starts but sputters and revs up and down between 1000 and 2000 rpm all by itself. Throws a code 1222 lambda control 1. The code of death. I have looked for vacuum leaks by smoking the intake. no leaks. I have clean and tested the throttle body and afm all is good. It acts like the air control valve is clogged but this throttle body has the eml feature. Fuel pressure is good. Thermostat tested good. O2 sensor replaced.

anyone out there have a clue?

[shogun]

We had that 2 times on an E32 750 Alpina B12.
First time the ground cable from the engine to chassis was bad. That we replaced and idle was stable.

Second time the return line from fuel tank = fuel tank breather line and the valve were defective/broken. See here on the B12 http://e32b12.blogspot.jp/ click in the index on idle and scroll far down.
That is the system on a M30 http://www.realoem.com/bmw/enUS/showparts?id=GC43-USA-12-1990-E32-BMW-735iL&diagId=16_0112
17 Fuel tank breather valve BOSCH 13901711395
The tank breather valve should have a resistance of 45 ± 20 Ohm and should be closed without power.

others:
idle control valve
throttle valve
But as the car has EML, this can be neglected. How about the vacuum hose under the intake? http://i1275.photobucket.com/albums/y446/CroughtonE32/DSC00204_zpsdqxehvrp.jpg
http://www.bimmernut.com/forum/showthread.php/44874-Hello-from-Spain!

http://www.bimmerforums.com/forum/showthread.php?2290326-M30b35-intake-manifold-gaskets

http://blog.bavauto.com/8393/bmw-m30-engine-vacuum-and-intake-hose-diagram-e23-e24-e28-535i-635csi-735i/

Just found a thread on the German forum, there it was the DME http://www.7-forum.com/forum/5/m30b30-pumpender-leerlauf-1-000-1-a-167325.html

[Kibokojoe]

Smoked the intake and checked all of the hoses. They are all good. With respect to the grounding strap there is only one correct? It is under the air filter canister. I replaced this grounding strap.....I will have to read up on the fuel tank breather line, never worked on this part of the car. Will keep you posted.


We had that 2 times on an E32 750 Alpina B12.
First time the ground cable from the engine to chassis was bad. That we replaced and idle was stable.

Second time the return line from fuel tank = fuel tank breather line and the valve were defective/broken. See here on the B12 http://e32b12.blogspot.jp/ click in the index on idle and scroll far down.
That is the system on a M30 http://www.realoem.com/bmw/enUS/showparts?id=GC43-USA-12-1990-E32-BMW-735iL&diagId=16_0112
17 Fuel tank breather valve BOSCH 13901711395
The tank breather valve should have a resistance of 45 ± 20 Ohm and should be closed without power.

others:
idle control valve
throttle valve
But as the car has EML, this can be neglected. How about the vacuum hose under the intake? http://i1275.photobucket.com/albums/y446/CroughtonE32/DSC00204_zpsdqxehvrp.jpg
http://www.bimmernut.com/forum/showthread.php/44874-Hello-from-Spain!

http://www.bimmerforums.com/forum/showthread.php?2290326-M30b35-intake-manifold-gaskets

http://blog.bavauto.com/8393/bmw-m30-engine-vacuum-and-intake-hose-diagram-e23-e24-e28-535i-635csi-735i/

Just found a thread on the German forum, there it was the DME http://www.7-forum.com/forum/5/m30b30-pumpender-leerlauf-1-000-1-a-167325.html

[Kibokojoe]

Funny...http://e32b12.blogspot.jp/ Is in Japanese. Although I was born in Tachakawa I can not read Japanese. I take it from the pictures you rebuilt the valve? Or just opened it up to see how it worked? That's a pretty pricey valve. $150 USD

[Kibokojoe]

Ok I tested the breather valve, 45.6 ohm so coil is good. A little confused you said "should be closed without power" Without power I can blow in the direction of the arrow only. Should the valve be completely closed in either direction?



We had that 2 times on an E32 750 Alpina B12.
First time the ground cable from the engine to chassis was bad. That we replaced and idle was stable.

Second time the return line from fuel tank = fuel tank breather line and the valve were defective/broken. See here on the B12 http://e32b12.blogspot.jp/ click in the index on idle and scroll far down.
That is the system on a M30 http://www.realoem.com/bmw/enUS/showparts?id=GC43-USA-12-1990-E32-BMW-735iL&diagId=16_0112
17 Fuel tank breather valve BOSCH 13901711395
The tank breather valve should have a resistance of 45 ± 20 Ohm and should be closed without power.

others:
idle control valve
throttle valve
But as the car has EML, this can be neglected. How about the vacuum hose under the intake? http://i1275.photobucket.com/albums/y446/CroughtonE32/DSC00204_zpsdqxehvrp.jpg
http://www.bimmernut.com/forum/showthread.php/44874-Hello-from-Spain!

http://www.bimmerforums.com/forum/showthread.php?2290326-M30b35-intake-manifold-gaskets

http://blog.bavauto.com/8393/bmw-m30-engine-vacuum-and-intake-hose-diagram-e23-e24-e28-535i-635csi-735i/

Just found a thread on the German forum, there it was the DME http://www.7-forum.com/forum/5/m30b30-pumpender-leerlauf-1-000-1-a-167325.html

[Kibokojoe]

Ok after studying the evap system. I decide to pinch off the hose from the breather valve just before it goes into the intake manifold. Started the car and it rev up and down for about 5 seconds and then stopped. Idle was about 2000 rpm but then again it is like 5 degrees Fahrenheit here. I let it run for about a minute and the idle started to lower itself, but it start reving up and down again. I think I need to reset the computer


Ok I tested the breather valve, 45.6 ohm so coil is good. A little confused you said "should be closed without power" Without power I can blow in the direction of the arrow only. Should the valve be completely closed in either direction?

[shogun]

Funny...http://e32b12.blogspot.jp/ Is in Japanese. Although I was born in Tachakawa I can not read Japanese. I take it from the pictures you rebuilt the valve? Or just opened it up to see how it worked? That's a pretty pricey valve. $150 USD
Ok I tested the breather valve, 45.6 ohm so coil is good. A little confused you said "should be closed without power" Without power I can blow in the direction of the arrow only. Should the valve be completely closed in either direction?

You can switch to another language on that site top left, automatic translation, not good, but helps.

We only opened up the valve to test and made some pics, had some used ones here we installed then.
As for the valve, BMW pilot here says: apply 12v and CLICK - no air either way. Re-install and no more idle hunt. http://www.bimmerboard.com/forums/posts/1264324
I am not sure about this, maybe somebody has tested it, or can you test on one of your other cars?

[shogun]

That is now a bit confusing. On the German forum someone mentioned without power it is closed, on Bimmerboard E34 forum it was mentioned that WITH 12V it was closed to both sides:

Symptom - Cold Engine, E34 535 M30 - start Ok - idles at 750 for 1 sec then hunts 8 to 11 times between 750 and 1000, then idles at 750 rpm - runs great, instant pickup when given a squirt, drives as it should.
Warm to hot engine - start - idles 750rpm. It was the EPV - or Evap Purge Valve stuck open.
12v at terminal to EVAP PV, could blow gentle air both ways through.
Apply 12v to EVAP PV - no click - no close - still open air both ways
Started with Carb cleaner, then brake cleaner then WD40 small amounts of compressed air - LOTS of BLACK expelled from both sides. Sprayed WD40 into both tubes - left over night - repeated several times until clear WD40 was expelled. let dry.
Apply 12v and CLICK - no air either way. Re-install and no more idle hunt.

[Kibokojoe]

Ok we finally found the problem. It appears the engine grounding wire was not secure and unfortunately it used the throttle body as a ground and fried it. Last week my son found one of these drive by wire throttle bodys and we installed it. After sitting in a field since December it is back up and running. Actually after a new tank of gas it is running better than it ever has.

[shogun]

Thanks for the feedback, Joe. Hope you made a good new ground wire now.

[Kibokojoe]

Actually made and installed two, one for the original and one so I will never have that problem again.

[shogun]

Recently I also read about some cases where the EML control module failed. Engine did not start, another case the EML light did not go out = ran in limp mode, another case engine could not rev to max.

[genphreak]

That sounds pretty comprehensive, hard too argue.

However I wouldn't be too keen about passing carb and brake cleaner through that little valve, I'm pretty sure it would have a small butyl rubber seal which would not take kindly to that harsh a clean. Even WD40 overnight...

I remember troubleshooting mine once, after installing a new charcoal cannister I wanted to verify it was ok. I figured that closed one way (NC) without power in direction of the arrow was normal, and that with power it opened so test was good. It was for sure the original valve from factory on a euro 10/88 M30B35. Oh, and it was running 100%, no idle hunt.

Have you tried disconnecting the ICV, O2 sensor and the AFM? If it idles ok missing one, perhaps that is the culprit? Is the ICV working nice, smooth and free? Is the TPS clicking closed when @idle? (Not sure how this translates to a EML/fly by wire setup, or whether it has a TPS or some other feature.

[Kibokojoe]

Resolved. Bought another throttlebody and that fixed it

[shogun]

Try to clean the throttle body, here are instructions how to clean the M70 EML throttle body, often the carbon brushes get stuck. Might be a bit different for the M30 EML DK, but this is a general guideline
http://www.mwrench.com/Whitepapers/DKMotorcleanup.pdf
http://bmwe32.masscom.net/moswald/750il_throttle_assemblies/index.html