Car turning off by itself upon ignition sometimes

System Of A... wrote

Hey guys, so I just started having this problem 3 days ago. It doesnt always happen, but when it does, I turn on the car, it turns on, then proceeds to rev down and shuts off. I replaced the idle control valve yesterday, but today it happened again a few times. It hunts for an idle, then dies. Only happens maybe 20% of the time now though, its tough to replicate it. But before I changed the ICV it happened 80% of the time for that one day that this problem started. What can I do? I have changed the throttle actuator 2 months ago. Its an 08 e93 m3 with about 80k miles on deck, but with a 4.6 motor with about 6k miles. Just got an oil change 3 days ago too the day it started happening. Any help is appreciated thanks.

And I should say, in neutral the chances of it shutting down while the car is on are much higher. Also, when Im driving and at a red light or a stop, it doesnt obviously hunt for an idle, and is consistent. It only hunts when its about to die the times it does.

dpilat8588 wrote

I had a similar issue with my 328xi a few years ago. I ended up having to replace the ECCENTRIC SHAFT SENSOR (luckily I was still under factory warranty).

System Of A... wrote  

dpilat8588 wrote

I had a similar issue with my 328xi a few years ago. I ended up having to replace the ECCENTRIC SHAFT SENSOR (luckily I was still under factory warranty).

would an oil leak be contributing to the need to replace this part? i have a minor oil leak..

System Of A... wrote

would an oil leak be contributing to the need to replace this part? i have a minor oil leak..

MilehighM3 wrote

The M3 doesn't have an eccentric shaft sensor, they are only used on engines with valvetronic. You may have a defective fuel tank vent valve. Do you notice if it's more prone to stalling after refueling?

///mawana wrote

We don't have that part on the s65 and I doubt an oil leak would have anything to do with what you are experiencing unless perhaps your valve covers are leaking.

My suspicion is this is a classic case of a minor vacuum leak that only has effect at idle and slow speed transitions. At high speed, the engine is drawing more air thus overwhelming the presence of a minor leak. You can either hunt for the leak now or wait til it gets large enough to throw a code.

System Of A... wrote  

ya, i had the codes read and there were none. hmm, when the leak gets large enough will the code specify where the leak is? and if i leave it alone for now will the car gradually get to the point where it will no longer start at all?

MilehighM3 wrote

The other common symptom to a failed tank vent valve, besides an applicable code and service engine light, is saturation of the charcoal canister. This typically results in a strong fuel smell from the left rear of the car and is intensified by warmer weather.

The other possibility is a loose or damaged connection on the bottom of the plenum since you recently had it removed for icv replacement. Be sure to double check your installation as that can cause an issue like this as well.

MilehighM3 wrote

The other common symptom to a failed tank vent valve, besides an applicable code and service engine light, is saturation of the charcoal canister. This typically results in a strong fuel smell from the left rear of the car and is intensified by warmer weather.

The other possibility is a loose or damaged connection on the bottom of the plenum since you recently had it removed for icv replacement. Be sure to double check your installation as that can cause an issue like this as well.

MilehighM3 wrote

The other common symptom to a failed tank vent valve, besides an applicable code and service engine light, is saturation of the charcoal canister. This typically results in a strong fuel smell from the left rear of the car and is intensified by warmer weather.

The other possibility is a loose or damaged connection on the bottom of the plenum since you recently had it removed for icv replacement. Be sure to double check your installation as that can cause an issue like this as well.

Mike Benvo wrote

Bad/loose cam sensor will definitely cause the car to turn off or run very poorly. Good thing it's easy to change from under the car.

System Of A... wrote

another update, i was on my way to pick up the fuel tank vent valve from a shop, and i got an engine malfunction. my exhaust got way louder and i felt some shakes. car turned off at a red light and wouldnt turn on for about 10 minutes. finally turned on, i got to my shop, they ran the codes and i got misfires on all cylinders, and 2 codes. 2796h and 27c1---> camshaft sensor / unknown fault code / master Camshaft sensor fault / Info tank empty at fault entry? so the camshaft sensor needs to be replaced?

My shop also told me that theres no way that this problem is from the fuel tank vent valve. So I dont know..any help? I cant do anything till monday besides wait and hope the car doesnt permanently die.

///mawana wrote

27c1 is thrown together with real faulty codes if you are low on fuel. 2796 pretty much all the time when there is a problem.

Check for vacuum leaks, yes I repeat, the gaskets on the hose to the idle control device do sometimes disintegrate so as the exhausts gaskets before the cats.

MilehighM3 wrote

The M3 doesn't have an eccentric shaft sensor, they are only used on engines with valvetronic. You may have a defective fuel tank vent valve. Do you notice if it's more prone to stalling after refueling?

hank90m3 wrote

MilehighM3 wrote

The M3 doesn't have an eccentric shaft sensor, they are only used on engines with valvetronic. You may have a defective fuel tank vent valve. Do you notice if it's more prone to stalling after refueling?

HI ~MilehighM3

can you give me fuel vent valve part number? thank you~

my m3 prone to stalling after refueling,so,I doubt my fuel vent valve fault~~