Originally Posted by dlbrooks18
My tech indicated that most of the major problems he services on N54 engine (and he's seen it all) are ultimately related to bad gas.. sucks for those of us in Cali, I don't think these cars were really engineered to run on 91, so now I'm always mixing in a little race gas to raise the octane level.. I wonder how long I'll go before needing a new fuel pump, 7500+ miles and counting though..
bad gas might cause the problem but not if you are stock. and if its a constant misfire in one cylinder its probably the injectors or spark plug