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Discussion Starter · #1 · (Edited)
Hi Everyone. First I want to say THANK YOU for the wealth of info I have found here since purchasing my car. However, I have been searching for days regarding rough idle, and nothing is quite as specific to my case as I would hope. I will describe situation below, and any help / ideas offered would be greatly appreciated.

2001 325i (M54 engine) 160k/miles

Began to idle roughly a couple months ago. Erratic, jumpy tach. The ONLY change prior to problem was a fill up with Texaco Super instead of Chevron. Problem is intermittent and unpredictable. Sometimes start and idle fine, but after two miles stalls when at stop light. Then next traffic light it will idle fine again. It feels like a small hesitation when starting from complete stop, but power is mostly fine. Once, power sucked (like it was on 3 cylinders) but the next day strong again.



Car was due for inspection so:

At home: Changed oil; replaced air and fuel filter; replaced possibly bad hose; reset codes; disconnected battery PROBLEM NOT SOLVED; CAR BEGANS TO STALL AND DIE OCCASIONALLY ---codes thrown were mostly misfire

Took car to indi BMW mechanic who claims to have: smoke test = no vacuum leaks; replace spark plugs (they had about 40k miles on them); clean ICV, clean injectors; swap MAF with strong running car and determines, since donor MAF does not fix idle, my MAF is not the problem. NOW CAR DIES EVERY TIME AT STOP. Mechanic wants to replace ICV, but I say no thanks and pick car up.

At home: Replaced ICV valve; cleaned MAF with MAF cleaner (no q-tips, only spray). PROBLEM NOT SOLVED; during this tinkering, notice that when MAF is unplugged, car idles steady. Plug MAF in and car chugs and glugs. ---Codes thrown: misfire, and coolant thermostat jammed open

Spoke with Mechanic cuz I wanted to return ICV (I cleaned old one upon replacing, and it seems to function just fine, although haven't put it back in car yet). Mechanic says car can take up to 600 mi to "recognize" new ICV (really? ...can't drive the car 600mi when it dies at every stop!). Mechanic also says maybe there is carbon build up in manifold under injectors that is sucking up the fuel at idle.

My thought is to replace MAF, since when it's plugged in, problem appears. But I can't keep putting money in this car when it's not fixing the problem.

Please, any information or thoughts if you have had this experience. I'm happy to provide more info if you need it and if I can get it. Going to reset codes again today, leave MAF uplugged and see what I get....
 

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Das rampen abwarten
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Just to clarify.
Did you say that the mechanic already tried replacing the MAF with a known functioning one and it still exhibited the same issues?
 

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Hmm, wonder if the VANOS seals have gotten to a point of total failure. See if this could be your problem: http://www.beisansystems.com/procedures/vanos_procedure.htm
I had the same "stalling" problem. My car has 130K/miles.. No code thrown. After replacing the vanos a few days ago, it seems more stable. Haven't stalled yet. I'm not sure if this is root of the problem -- its too soon to declare victory. I have tried many things in the pass, to only have this issue re-appear after a few weeks or a couple months.

However, since the OP car has so many miles already, minus well replace the vanos. It couldn't hurt. That was my thinking when I replaced mine.
 

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Discussion Starter · #7 ·
Just to clarify.
Did you say that the mechanic already tried replacing the MAF with a known functioning one and it still exhibited the same issues?
Yes. He SAID he did. I asked, "how do you know the MAF from other car was good?", Mechanic said, "because the other car runs fine". Car still exhibited same issues.

""quote"""If it is the MAF, it would try cleaning it first before you just replace it. ""quote""
I cleaned MAF with MAF cleaner, just spray, no q-tips. Nothing changed.

Drove it today, with MAF disconnected. Didn't stall. Idle roughly, but steady. At very slight throttle pressure (barely more than coasting) it can be jumpy, from 500 to 1500 rpm. Got fault code 08 Air Mass Sensor (keep in mind, this ONLY shows when MAF is disconnected. If MAF is plugged in, I get misfire codes and recently coolant thermostat jammed open.

THanks for the VANOS idea, I've just recently become aware of that one, and will check into it more. In the meantime..

I don't know whether or not to spend the money on a MAF??

Thx
 

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ROLL TIDE!
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Sounds like a couple things to me: 1. (probable cause) bad or about to be bad cam sensor. Sort of tough to pinpoint which one without a code. 2. (less likely) VANOS related, though I have never heard of stalling from VANOS seals and I doubt it is causing the stall, it might be causing poor idle but even then, the poor idle was on the M52tu which you do not have. 3. (perhaps) bad or dying fuel pump. 4. Injector problems.

I really think cam sensor though, if that fails your car WILL stall for sure. Seen it many times.
 

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I had the same "stalling" problem. My car has 130K/miles.. No code thrown. After replacing the vanos a few days ago, it seems more stable. ...
Did you actually replace the VANOS unit, or rebuild it with new seals? The problem is apparently with the seals, as they are made of buna-N rubber, and bathed in synthetic oil. As immediately identified by a couple of my rather knowledgable mechanic buddies, buna-N rubber swells when introduced to synthetic oil. As a result, the VANOS pistons get sticky in their bores, and can't function properly; they're responsible for cam timing.

If you dig deep enough into the troubles over on the link I gave earlier, you'll find that new VANOS units typically fail within 20k miles; though, some survive to 60k miles. I've got 66k on my '05 engine, so a seal replacement is on my short to-do list. Another thing I just fixed, which may be a contributor to jrutledge's problems, is the lower intake manifold. While jrutledge's engine isn't throwing lean codes, there may be a tear in the lower intake manifold boot. By the time my car threw a code, I found a tear large enough to stick my index finger into the boot and touch the throttle body. Search around, I'm sure you'll find the problem.

Good luck, and keep us updated!
 

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Discussion Starter · #10 · (Edited)
Rough Idle and Stalling_Update

I'm still having the idle problem with my 2001 325i, 160k. Very frustrating and expensive. I have done the following to the car:

1. Changed oil; replaced air and fuel filter; replaced possibly bad hose; reset codes; disconnected battery ---codes thrown were mostly misfire

2. smoke test = no vacuum leaks; replace spark plugs (they had about 40k miles on them); clean ICV, clean injectors; swap MAF with strong running car and determines, since donor MAF does not fix idle, my MAF is not the problem.

3.Replaced ICV valve; cleaned MAF with MAF cleaner (no q-tips, only spray). PROBLEM NOT SOLVED; during this tinkering, notice that when MAF is unplugged, car idles steady. Plug MAF in and car chugs and glugs. ---Codes thrown: misfire, and coolant thermostat jammed open

4. Inspected and clean Adjuster Unit. Appears to be working correctly.

5. Resealed gasket of Adjuster Unit with sensor safe gasket maker.

The car throws different codes between all of this. Lots of misfire codes, and intermittently: "coolant thermostat jammed open", "o2 sensor control limit", "cat convertor efficiency".

The car runs ok when cold, but after a few minutes (usually by the time I hit the first stop light), it will idle erratically and sometimes stall. When sitting in driveway, if I give it lots of gas, and then release, it will choke out trying to return to idle. If I give is just a bit of steady gas, it will idle steady when throttle is released.

What to do now? Coils? O2 sensors? New MAF? New Adjuster Unit? I am not a mechanic and have no idea how to tell if these things are bad or not except by replacing them.

I've spent hours reading these forums and any other BMW info I can find. Still at a loss. Any ideas are appreciated. Thank you.
 

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ROLL TIDE!
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I'm still having the idle problem with my 2001 325i, 160k. Very frustrating and expensive. I have done the following to the car:

1. Changed oil; replaced air and fuel filter; replaced possibly bad hose; reset codes; disconnected battery ---codes thrown were mostly misfire

2. smoke test = no vacuum leaks; replace spark plugs (they had about 40k miles on them); clean ICV, clean injectors; swap MAF with strong running car and determines, since donor MAF does not fix idle, my MAF is not the problem.

3.Replaced ICV valve; cleaned MAF with MAF cleaner (no q-tips, only spray). PROBLEM NOT SOLVED; during this tinkering, notice that when MAF is unplugged, car idles steady. Plug MAF in and car chugs and glugs. ---Codes thrown: misfire, and coolant thermostat jammed open

4. Inspected and clean Adjuster Unit. Appears to be working correctly.

5. Resealed gasket of Adjuster Unit with sensor safe gasket maker.

The car throws different codes between all of this. Lots of misfire codes, and intermittently: "coolant thermostat jammed open", "o2 sensor control limit", "cat convertor efficiency".

The car runs ok when cold, but after a few minutes (usually by the time I hit the first stop light), it will idle erratically and sometimes stall. When sitting in driveway, if I give it lots of gas, and then release, it will choke out trying to return to idle. If I give is just a bit of steady gas, it will idle steady when throttle is released.

What to do now? Coils? O2 sensors? New MAF? New Adjuster Unit? I am not a mechanic and have no idea how to tell if these things are bad or not except by replacing them.

I've spent hours reading these forums and any other BMW info I can find. Still at a loss. Any ideas are appreciated. Thank you.
Given all you have done you may want to check the fuel pump. When they are about to die, this can happen. Very easy to remove and test.
 

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Rough Idle

Given all you have done you may want to check the fuel pump. When they are about to die, this can happen. Very easy to remove and test.
Currently have all the same issues you are having/had after replacing the Maf(not the problem) took it to a beamer mechanic(charged me 350 to fix a little hole in the boot) never go to a dealership again). Left the shop and realized still running rough. took engine cover and intake manifold cover off. Sprayed carb cleaner while car running and realized the cvv(crankcase vent valve BMW name for a PCV valve) is sucking air. Only problem is replacing this part is not as simple as a normal pcv valve job.
 

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Currently have all the same issues you are having/had after replacing the Maf(not the problem) took it to a beamer mechanic(charged me 350 to fix a little hole in the boot) never go to a dealership again). Left the shop and realized still running rough. took engine cover and intake manifold cover off. Sprayed carb cleaner while car running and realized the cvv(crankcase vent valve BMW name for a PCV valve) is sucking air. Only problem is replacing this part is not as simple as a normal pcv valve job.
Holy thread resurrection...

If the dealer charged you for a fix that wasn't a fix, you should have returned to them and insisted on a refund or that they correct your problem at no charge.

Didn't know the carb cleaner method was a way of diagnosing a bad CCV, but if your sure of the issue, well done.

Lot of failed or failing CCV instances in the E46, discussed much here. A couple of outstanding instructions for replacement in the wiki if you're a do-it-yourselfer, under the section Oil Separator Valve, Idle Control Valve, DISA valve Replacement.

Read the wiki, love the wiki:

http://www.bimmerfest.com/wiki/index.php/BMW_E46
 

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testing a mass air flow sensor

Do you know what codes it threw? Sounds like you know what the problem is. A new MAF is expensive, so see if you can find a used one somewhere. When I disconnected my MAF once it ran roughly and threw a code.
Yeah! that's definitely a sign of a good working (MASS SENSOR) It happened to me once while I was testing my Air mass sensor to see if it was working properly. When I pulled the plug, the engine hesitated roughly like it was about to die; but I quickly pushed down the plug to it's place. So by the way I know that I have a good working mass sensor.

Otherwise! it would not react any such symptom when you pull the plug while the engine is running.

(2001 BMW X5 4.4i)
 

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I have a 2002 325i and got miss fire codes and the mass air flow code. have an rough idle. it sometimes gets worse, but if you shut off the engine and restart it clears the problem for awhile. Also if you touch the gas alittle in park or neutral it almost stalls and then jumps to 2000rpm then back. Mass airflow sensor or idle control???
 

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My 2002 325I used to occasionally idle rough at stoplights, though it never stalled or anything. New VANOS fixed it.
 

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My 2003 325i has a lot of the same issues described in the thread, rough idle, maybe low idle and intermittent idle RPM hiccups where it dips very low under 500 RPMs. I read the write up for VANOS and it mentioned the A/C makes the problem worse. My car rough idle goes away when i turn on the A/C, RPM's go up to about 800 and everything seems fine. My car has stalled a couple times at takeoff, but car seems fine when driving and at higher RPM's. I have power when I step on the gas. One other thing I have not seen mentioned in any posts is my car, when coming to a stop i notice that the gas efficiency gauge goes up like i am stepping on the gas, but i am coming to a stop. Any ideas would be appreciated.

Oh forgot to mention, I have changed O2 sensors (pre only), spark plugs, fuel filter, cleaned (not replace) MAF, can’t seem to find any vacuum leaks, replaced a broken adjuster unit, and cleaned the ICV.
Thanks,
 

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It worked!!!!!!!!!!!!!!!!!!! I had my garage replace the CCV because of the routing of the hoses! Didnt want to take a chance that one didnt seal just right. My Lights dont dim, I dont get misfire codes, and I can sit at a red light all day without problems....
 
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