The 1996 Z3 I purchased appears to have the original Bosch plugs (40k on car). Car has rough idle, which I suspect is plugs. Before I install OEM replacement wanted to see if there is a better alternative (Bosch or NGK).
spark plugs Let me know if that fixes your idle issure. I have not been in a 4 cylinder Z3 that didnt have a slightly rough idle. My 96 Z has a slight rough idle too, and I changed the plugs. I would love to make it as smooth as my 325i.
Rough Idle Concern The first Z3's that were sold had an inherent rough idle by design. It was not until about a year or so later that BMW came out with a bulletin to adjust the intake camshaft timing using a special tool. The adjustment works rather well and besides a smoother running engine, I personally feel their is also a gain in engine performance. I did quite a few adjustments over my years at the BMW dealer. Just something you may want to consider. Please note that many cars have been already updated, but only if it was originally requested by the customer.
