Advice needed on rough start/idling
I've got a '08 N52 3.0 naturally aspirated motor. At every warm start, the engine runs rough for like 1 to 2 minutes. It almost disappears after about 2 minutes but a sensitive person can still feel some unevenness in idle whenever I'm stopped.
But when I unplug the eccentric shaft sensor, the symptom doesn't show up anymore. From what I've researched, unplugging the eccentric shaft sensor disables valvetronic and the valve lift is set to maximum at idle. I've also heard, for N52 engines, the valve lift can't be adjusted as it's automatic. So which parts of valvetronic should I replace to fix this issue? Yeah, I'm throwing parts at it but I think I'm this close to finding out the root of this problem. BTW, no codes. |
Oh, BTW, the eccentric shaft sensor has already been replaced but no difference.
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That is not the proper way to diagnose or fix a modern car.A simple scan with DIS or ISTA will tell you the problem with a very high probability to be fixed at first attempt.
Here is how the valvetronic works:the TB is closed at start-up and opens completely a few seconds after the engine is running.The function of the TB (regulating engine RPM and output) is performed by the Valvetronic:min valve lift=idle,max valve lift=max power,and everything in between.If there is a malfunction in the Valvetronic system registered by the ECU,valve lift is set to max and the Valvetronic is disabled.At this point the engine is controlled exactly as a conventional engine-with the TB. |
from elsewhere:
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agree that scanning the DME with something way more involved than a OBD code reader is the way to go... |
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