Question about BMW Z3
P0301 is a misfire on number one cylinder that is the rough running, as to what the source of that is will require a thorough diagnosis, it is not cut and dry and it can be a multitude of things causing the miss, start with the ignition system, poss causes are in order of how common it is
1. Defective spark plug
2. Defective ignition coil for #1 cylinder
3. Intake manifold vacuum
4. Defective fuel injector cylinder #1
5..Defective #1 fuel injector driver circuit of Powertrain control module
6.. Engine mechanical problems, low compression due to scoured cylinder or burnt valve or flat cam shaft lobe etc..
Fuel trim lean, the unburned fuel from #1 cylinder misfire going out the exhaust is causing this problem I think, but it could be be the MAF (mass airflow sensor) sensor, I suggest u isolate the problem with the #1 cylinder and repair it then clear the codes and drive it, if the light comes back on and the code P170 comes back try cleaning the MAF sensor, many times that cures the problem.
Posted on Apr 29, 2010
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Posted on Jan 02, 2017
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