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

  1. #1
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    Default e32 735i '91 engine starts, sputters, revs up + down between 1000 + 2000 RPM - solved

    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?

  2. #2
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    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/show...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/...psdqxehvrp.jpg
    http://www.bimmernut.com/forum/showt...llo-from-Spain!

    http://www.bimmerforums.com/forum/sh...nifold-gaskets

    http://blog.bavauto.com/8393/bmw-m30...i-635csi-735i/

    Just found a thread on the German forum, there it was the DME http://www.7-forum.com/forum/5/m30b3...-a-167325.html
    Last edited by shogun; 12-16-2016 at 03:03 AM.

  3. #3
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    Default will check it out

    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.

    Quote Originally Posted by shogun View Post
    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/show...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/...psdqxehvrp.jpg
    http://www.bimmernut.com/forum/showt...llo-from-Spain!

    http://www.bimmerforums.com/forum/sh...nifold-gaskets

    http://blog.bavauto.com/8393/bmw-m30...i-635csi-735i/

    Just found a thread on the German forum, there it was the DME http://www.7-forum.com/forum/5/m30b3...-a-167325.html

  4. #4
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    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

  5. #5
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    Default breather valve

    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?


    Quote Originally Posted by shogun View Post
    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/show...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/...psdqxehvrp.jpg
    http://www.bimmernut.com/forum/showt...llo-from-Spain!

    http://www.bimmerforums.com/forum/sh...nifold-gaskets

    http://blog.bavauto.com/8393/bmw-m30...i-635csi-735i/

    Just found a thread on the German forum, there it was the DME http://www.7-forum.com/forum/5/m30b3...-a-167325.html

  6. #6
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    Default update

    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

    Quote Originally Posted by Kibokojoe View Post
    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?

  7. #7
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    Quote Originally Posted by Kibokojoe View Post
    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?

  8. #8
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    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.

  9. #9
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    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.

  10. #10
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    Thanks for the feedback, Joe. Hope you made a good new ground wire now.

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