Hello everyone,
my 2.0i E85 Z4 (N46B20B engine) recently has a problem idling. When the car is properly warmed up and is idling, the engine rpm would fluctuate a little at 800, then suddenly dip to 500 and jump back up again, leading to engine almost stalling. It's annoying especially when the car comes to a stop at traffic lights.
However, the car idles normally when cold, and runs just fine when not it's idling. There were no error codes.
I have checked the forum for possible causes and solutions, cleaned the throttle body, MAF sensor, VANOS solenoid, replaced spark plugs (although spark plugs not really related) in the past few weeks, but still no success. The 2.0i does not have ICV unit, the throttle body is controlled electronically by ECU, so it couldn't be ICV's fault. Yesterday I replaced the PCV valve and its hoses all at once, thinking it could be the culprit of the idling problem. The old PCV was indeed filthy and the hoses have milky residue.
But after replacing the PCV, the idling problem still persists. And now on top of that, an error code P1250 (fuel level low) is also popping up, which is confusing. I am leaning towards the case that it's just a vacuum leak but have no idea where to pinpoint the possible leak location, so I just make sure all the intake hoses are tightly seated.
I am now running out of ideas. Does anyone have any experience in this regard?
my 2.0i E85 Z4 (N46B20B engine) recently has a problem idling. When the car is properly warmed up and is idling, the engine rpm would fluctuate a little at 800, then suddenly dip to 500 and jump back up again, leading to engine almost stalling. It's annoying especially when the car comes to a stop at traffic lights.
However, the car idles normally when cold, and runs just fine when not it's idling. There were no error codes.
I have checked the forum for possible causes and solutions, cleaned the throttle body, MAF sensor, VANOS solenoid, replaced spark plugs (although spark plugs not really related) in the past few weeks, but still no success. The 2.0i does not have ICV unit, the throttle body is controlled electronically by ECU, so it couldn't be ICV's fault. Yesterday I replaced the PCV valve and its hoses all at once, thinking it could be the culprit of the idling problem. The old PCV was indeed filthy and the hoses have milky residue.
But after replacing the PCV, the idling problem still persists. And now on top of that, an error code P1250 (fuel level low) is also popping up, which is confusing. I am leaning towards the case that it's just a vacuum leak but have no idea where to pinpoint the possible leak location, so I just make sure all the intake hoses are tightly seated.
I am now running out of ideas. Does anyone have any experience in this regard?
. As for the error code, it was indeed caused by a vacuum leak due to bad intake manifold rubber seal.