Is he getting a good spark at each plug? The old fashioned way is to pull one boot with plug in it and hold it near a good ground (insulate the boot or wear a rubber glove or something), you can pull it first and crank the engine or just do one at a time while the car is running. You should get a nice blue spark. Do it for each plug. If you don't have spark on one side or you have a weak-looking spark on some plugs, it could be one bad (or failing) distributor. Not sure about my 750il, but I have fixed my old muscle cars with this test. Heck, there are two distributors on this car--maybe one is dying. It could also be gummed-up plugs or a bad plug wire set on one side put in by a previous owner.
The O2 sensor should be working, however. Can you set up (or splice or rig or beat with a hammer) the inputs from both O2 sensors, so that they will read from only one side or the the same exhaust cat? Just to test? Seems like you could trick the computer into working that way if it is just an O2 sensor issue. My in-laws own an engine shop and they say most of the "drivablity" problems that they encounter are from disconnected or bad O2 sensors. I would think that you should get that thing working first, just to eliminate it. A good muffler/exhaust shop could tap in a bung or at least a place for that sensor to sit and read properly. Maybe they could repair the connection to the old 02 sensor. Just throwing out ideas...
Last edited by Whit; 03-07-2005 at 03:36 PM.
Whit
1988 750il (whoops, tricky title--probably not a 1994!)