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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E36 (1991 - 1999)

E36 (1991 - 1999)
The E36 chassis 3-Series BMW was a huge hit among driving enthusiasts from the first moment the car hit the pavement. The E36 won numerous awards over the years it was produced and is still a favorite of many BMW enthusiasts to this day! -- View the E36 Wiki

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  #1  
Old 01-31-2013, 03:35 AM
CalmGuy CalmGuy is offline
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Mein Auto: E36 318is
Arrow Car accelerates by itself / high idle

The car is '93 E36 with M42.

In most cases the car doesn't start on the 1st attempt. Still, I could perfectly live with that as long as it starts on the 2nd one. But the problem is that when I start the engine, at the beginning it runs like a crap (not always, but very often). But then the car starts to accelerate by itself and idles at ~2000rpm like a champ.
If I switch off the engine while it does this crazy stuff, I have some trouble to start it again. Basically what I need to do then is to switch off fuel pump and only then crank the engine. When it starts, I switch fuel pump back on and the car continues to idle high.

Here is my video .
I need to mention, that at 1:36 and 1:40 I barely pushed the throttle and high idle even increased.

However, all of this doesn't happen all the time, in most cases only after starting the engine. If I let her to idle for some time/drive it/restart the engine couple of times/disconnect the battery over night, the idle suddenly drops and the car runs perfectly that day.


What have I done?
*Cleaned idle control valve, also replaced it with used one.
*Replaced coolant temperature sensor (Diagnostics showed its error so I replaced it with brand new one. That day the car was running great, there were no problems at all. But the following morning - same problems... Checked voltage in the sensor's plug - 5V, which is OK according to the Bentley manual.)
*Checked for vaacum leaks
*Tested throttle position sensor's resistance.
*Checked whether ECU is dry or not. It is.

Well, I'm out of moves. Don't know what else I can do. Any ideas would be greatly appreciated!!!
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  #2  
Old 04-24-2013, 05:28 AM
lexxy lexxy is offline
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Engine revs itself

I am having same problem with my 1998 E39 528i. I have done basically all that you have and canít get the problem resolved. I am considering getting rid of the vehicle at a giveaway but wonít have to if I could find the cause. i really do love my car. I will appreciate if you could post a threat when you get you problem resolved.
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  #3  
Old 04-24-2013, 10:39 AM
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hornhospital hornhospital is offline
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CalmGuy and lexxy, BOTH of you need to be looking for vacuum leaks. CalmGuy, you said you checked for them....how did you do that?

There's only one way a car can accelerate or run at a higher-than-normal idle: introduce more air into the intake. You do that by opening the throttle. If it's doing that with the throttle fully closed, air is getting in there somehow. Find the leak(s) and fix it. The M42 engine has a mass of small vacuum hoses under the upper intake manifold, including four that go to the injectors. If any of those are even slightly cracked, it will throw the idle way off. Start hunting!
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1995 318is "Bebe"; 1993 325is "Elvira" 1985 635CSi "Katja" 1984 633CSi "Sylvia"
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  #4  
Old 04-25-2013, 12:31 AM
lexxy lexxy is offline
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hornhospital. thanks for the prompt response, I will do a proper check for vacum leak this weekend.
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  #5  
Old 04-25-2013, 03:54 AM
hnaz hnaz is offline
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remove the throttle body, remove the manifold, pull out the ICV and clean it out. Replace the air hoses. Replace the boot that goes to the TB as well. Also, you may want to check and make sure the throttle cable is not getting stuck either. These are cheap fixes, but time consuming. It will pay off. Ask me how I know.
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  #6  
Old 04-25-2013, 04:13 AM
lexxy lexxy is offline
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Thanks for your contribution. I'd earlier replaced the ICV with another one, replaced the idle regulator and it was okay just for a day. the following day, returning from work in the afternoon, the reving started at it was with the help of my brakes that i was able to bring the bull to control in heavy traffic withough ramming into other cars. I engaged the gear in Neutral where it was also possible. The brake could barely hold the car to a halt because the tac was 3000/4000rpm. on a free highway that could have given me about 100mph. The only thing i havent done is to do a thorough check for leaks or cracks on the vacuum hoses which i will try this wekend. I hope i find something and bring this mistry to a halt as im so scared to drive this car again following my experience..
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  #7  
Old 04-25-2013, 04:24 AM
lexxy lexxy is offline
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the throttle cable is not jammed either. the revving goes from 1000 up to about 4000 repeatedly. this doesn't look like what a jammed throttle cable woould cause. A jammed cable i guess will keep the revving almost on the same rmp
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  #8  
Old 04-25-2013, 11:31 AM
CalmGuy CalmGuy is offline
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Yeah, high idle was really pain in the a$$ and was driving me crazy. Still, I managed to get rid of it! The problem was that one pin (to be exact - engine coolant temperature sensor pin) in the plug, which connects to ECU, was loose. Because of bad contact ECU was getting wrong temperature readings - between 0 and -30F and the car was idling crazy. Since the pin was resoldered my problems vanished.

Wish you the best of luck!
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  #9  
Old 04-26-2013, 01:07 AM
lexxy lexxy is offline
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CalmGuy, thanks for this great info. i would never have thought of that. I guess I would have to check this weekend. I am hoping I would find something and be a calm guy over the weekend like your name signifies.
I will update my thread on result. thanks for all your assistance guys.
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  #10  
Old 04-26-2013, 01:14 PM
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hornhospital hornhospital is offline
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Quote:
Originally Posted by CalmGuy View Post
Yeah, high idle was really pain in the a$$ and was driving me crazy. Still, I managed to get rid of it! The problem was that one pin (to be exact - engine coolant temperature sensor pin) in the plug, which connects to ECU, was loose. Because of bad contact ECU was getting wrong temperature readings - between 0 and -30F and the car was idling crazy. Since the pin was resoldered my problems vanished.

Wish you the best of luck!
Great bit of detective work! The reason it was still idling high was the ECU thought the engine was dead cold. It was adjusting the idle control valve open to raise the idle as if it had just been cranked on a very cold day. It will do the same thing if the coolant temperature sensor has failed.
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Quotes to live by:
guessing gets expensive...drivinfaster
nothing is more expensive than a cheap BMW...c4harpe13

Ken Kanne, Silverhill, AL, E36 Forum Mod/Craigslist addict/Hoarder of all sorts of stuff
BMW-CCA #441426
1995 318is "Bebe"; 1993 325is "Elvira" 1985 635CSi "Katja" 1984 633CSi "Sylvia"
HAVE I HAD MY MEDS YET?

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  #11  
Old 04-29-2013, 01:50 AM
lexxy lexxy is offline
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i have tried all the suggestions above with no improvement. checked for vaccum leaks and found none. checked the engine coolant temperature sensor pin and nothing wrong with it. the car is driving me really crazy now
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  #12  
Old 04-29-2013, 07:14 AM
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jonesin jonesin is offline
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Quote:
Originally Posted by lexxy View Post
i have tried all the suggestions above with no improvement. checked for vaccum leaks and found none. checked the engine coolant temperature sensor pin and nothing wrong with it. the car is driving me really crazy now
What did you do to check for leaks in the vacuum hoses?
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  #13  
Old 04-29-2013, 07:18 AM
lexxy lexxy is offline
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they were all checked for visual leaks or cracks, also I had a can of cabruator cleaner sprayed around the hosses and nothing changed. running out of ideas at the moment! any help
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  #14  
Old 04-29-2013, 07:24 AM
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jonesin jonesin is offline
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Including all the hoses under the manifold?
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I grew up in a time when the internet was just a baby. Grammar back then versus now... holy cow. You could watch the degradation of society as the internet became more mature.

HAS KEN HAD HIS MEDS YET?
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  #15  
Old 04-29-2013, 07:26 AM
lexxy lexxy is offline
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all the hoses under the manifold as well.
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  #16  
Old 04-29-2013, 07:31 AM
3star 3star is offline
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very strange issue. I would think the idle air valve is defective but u said u replacedthat. Only thing i can think of is a defective cruise control unit.

That can also accelerate the car.

Maybe the switch is stuck on or something. try disconnecting it and see what happens
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  #17  
Old 04-29-2013, 07:35 AM
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jonesin jonesin is offline
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http://www.popularmechanics.com/cars...-a-vacuum-leak

This article is fairly long but a good read detailing several ways to find and fix vacuum leaks.
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I grew up in a time when the internet was just a baby. Grammar back then versus now... holy cow. You could watch the degradation of society as the internet became more mature.

HAS KEN HAD HIS MEDS YET?
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  #18  
Old 04-29-2013, 07:38 AM
lexxy lexxy is offline
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Thanks, I will try the cruise control disconnection and see if it works. I also plan to also remove the intake alluminium manifold and check that also for cracks.
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  #19  
Old 04-29-2013, 07:40 AM
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jonesin jonesin is offline
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Good luck.
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Originally Posted by hnaz View Post
I grew up in a time when the internet was just a baby. Grammar back then versus now... holy cow. You could watch the degradation of society as the internet became more mature.

HAS KEN HAD HIS MEDS YET?
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  #20  
Old 04-29-2013, 07:43 AM
lexxy lexxy is offline
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thanks jonesin for that article. studying it for better understanding of the vacuum system.
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  #21  
Old 05-10-2013, 02:36 AM
lexxy lexxy is offline
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i might have to give up completely on this one. i have done bassically anything i could think of. checked all the vacuum and changed most, changed the manifold, idle regulator, tempeature and just to mention a few and no luck. the engine continues to rev seriously both stationary and in motion. the car is now undrivable. i have tried all the suggestions above still with no luck. at this stage i cant think of anything else
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  #22  
Old 05-10-2013, 10:48 PM
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hornhospital hornhospital is offline
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I said it to begin with, and I'll say it again: either the throttle plate is opening or you have a vacuum leak. You said you checked for a vacuum leak...how did you go about that?
__________________
Quotes to live by:
guessing gets expensive...drivinfaster
nothing is more expensive than a cheap BMW...c4harpe13

Ken Kanne, Silverhill, AL, E36 Forum Mod/Craigslist addict/Hoarder of all sorts of stuff
BMW-CCA #441426
1995 318is "Bebe"; 1993 325is "Elvira" 1985 635CSi "Katja" 1984 633CSi "Sylvia"
HAVE I HAD MY MEDS YET?

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