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Please help. 2001 330i, manual. Started stalling, engine light came on. found tear in small boot to idle control valve, replaced all boots. No more fault codes. But, when engine gets warm still loses idle when I release clutch at higher rpms(e.g. depress clutch pedal at 3000 rpm). Tachometer drops to 500 range or lower, sometimes recovers, sometimes stalls.
Have removed and cleaned MAF, idle control valve, and Intake Manifold Actuator (and sealed around the Intake Manifold Actuator gasket).
Help on what I should try next. These are expensive parts. Final point...inadvertently left the MAF unplugged, ran fine, no stall.
 

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If you disconnect the MAF and it solves the problem then that is the problem. Without the MAF connected the car runs on some predetermined stock settings i believe. These should be enough to make the car function normally. With the MAF connected the car is getting erroneous readings which sounds like they are causing breathing issues.
 

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This could be caused by the common problem of the Cam position sensor or crank position sensor failures. No fault code will be thrown when these fail. The MAF could be either the problem or a red herring.
 

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Dolph1354, I too have that problem. I have a 2001 330i 5-spd manual, production date 07/2000. My symptoms are just like yours. It's generally only when the car is warmed up, and I have the AC on. Whenever I have rpm's over say 1500/2000, and depress the clutch the rpm's drop, sometimes the rpms bounce until it recovers and comes to idle, but sometimes it just stalls. This really only happens when I have my AC on though.

I've been dealing with this for a while. I've had the car since it was new and don't recall this being an issue when I got it. I had my alternator replaced at one point, and I'm starting to suspect that as my cause. Given that the AC puts a burden on the electrical system. I haven't had a chance, but in the next week or so, I'm going to put a meter on my battery while running first w/o AC on, then with AC on and see if I'm maintaining the voltage, or if there's a drop. If there is, it may be that the refurbished alternator I had put in has a faulty voltage regulator.

That's just my guess right now. Let me know if you find your issue. I'll post back if I find mine.
 

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Continuing saga. The MAF sensor was not the problem-same issues with a new sensor - as Arty said a red herring. From others' posts, I suspected and now I know. JohnnyV be interested to see what you find in your test. I am thinking it is either one of the sensors (cam or crank position) beginning to fail when hot-but doing so inconsistently, or the ECU needs an update. Seems like the ECU problem would result in a more consistent fail/symptoms than a sensor starting to fail-but would like to hear what others think???
NicB thanks for the link-I searched a fair amount before my first post. I'll go thru your post-more to follow.
 

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Discussion Starter #12
NicB - doubt it is your MAF -I swapped mine and it did not solve the problem. Weird difference thought is that mine ran better with MAF unplugged, but was clearly running very rich -burned significantly more gas on my regular commute than typical.
 

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NicB - doubt it is your MAF -I swapped mine and it did not solve the problem. Weird difference thought is that mine ran better with MAF unplugged, but was clearly running very rich -burned significantly more gas on my regular commute than typical.
Yea, I'm doubting it is my MAF as well, I think you and I are experiencing the same issue.

Intake Cam Position Sensor. Mine was doing the same.
same here..
I've replaced both CPS with OEM parts, this didn't fix the problem for me. I do wonder if maybe it is the throttle position sensor (TPS) at times.
 

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I plan to try the intake cam position sensor next. Worrisome Nic B that this did not fix your problem.
I threw a code when the exhaust side went bad, didn't affect the way the car ran at all. I replaced the intake side pre-emptively, didn't change anything either. But, I do think it is good preventitive maintenance to perform, and if you are throwing a code, a must to replace.

Good luck and keep us posted.
NicB.
 

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Dolph1354, I too have that problem. I have a 2001 330i 5-spd manual, production date 07/2000. My symptoms are just like yours. It's generally only when the car is warmed up, and I have the AC on. Whenever I have rpm's over say 1500/2000, and depress the clutch the rpm's drop, sometimes the rpms bounce until it recovers and comes to idle, but sometimes it just stalls. This really only happens when I have my AC on though.

I've been dealing with this for a while. I've had the car since it was new and don't recall this being an issue when I got it. I had my alternator replaced at one point, and I'm starting to suspect that as my cause. Given that the AC puts a burden on the electrical system. I haven't had a chance, but in the next week or so, I'm going to put a meter on my battery while running first w/o AC on, then with AC on and see if I'm maintaining the voltage, or if there's a drop. If there is, it may be that the refurbished alternator I had put in has a faulty voltage regulator.

That's just my guess right now. Let me know if you find your issue. I'll post back if I find mine.
Any luck with this concern? I have a '01 325 that does the same thing. I cleaned the MAF last weekend and it seemed to help when the a/c is off, but while running the car today with the a/c on it stalled while I was creaping forward at a stop sign after I pushed the clutch in. I have a new idle valve, intake cam sensor, and no fault codes. I'll post if I find a solution
 

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When the AC is on, the compressor puts extra load on the engine, which can make an issue like this happen more often. As my bearings in the AC pump are toast, I don't run the compressor, but will eventually replace it with the $250 one at rockauto.
 
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