Re: M5 running rich (archive)

Sorry for the double post. My M5 is running rich- so much so that it floods the cylinders and won't start without removing and drying the plugs. My mechanic checked the fuel pressure and indicated that it was within spec. The check engine light has come on, but this problem preceded the appearance of the light. Anyways, can you read the fault code from inside the car by hitting the gas 5x with the ignition ON? Otherwise, besides unregulated fuel pressure, what might cause this. I don't think it is poor ignition (unless it is an insidiously intermittent problem) beacuse that also checked out (according to the mechanic). I am beginning to think this guy doesn't know too much- any suggestions? Should I drive the car (if only to a different mechanic)?
TIA
MAC
88 M5 129K

MAC-- I had the same problem with my '88 U.S. spec E28 M5 last year. Although, we never determined with certainty what the cause was, we were successful in solving the problem by cleaning the spark plugs and introducing several containers of dry gas into the fuel tank (suspect: a fill-up with water-contaminated gasoline). Have you checked the spark plugs? If they became fouled due to a previously existing, though not as extreme and hence undetected, rich condition (eg, water contaminated fuel), that would result in ever increasing amounts of unburned petrol blowing out the tailpipe accompanied increasingly rough, spit-and-stumble performance. Other suspects you may wish to look at: cracked hard rubber bellows connecting the throttle body to the air intake muffler (that's what the factory calls it -- you and I would call it the air filter box); cracked throttle body bellows (there is one for each cylinder); worn ignition wires or coil (though you've said your wrench already checked out the ignition system... hmmm). There are probably some other likely/usual suspects, but the dry gas and cleaning of the spark plugs may be the least expensive experiment to try, combined with a thorough visual inspection of all the intake bellows (no mechanic or parts charges involved). Good luck.

Chris
Bimmers Currently Owned:
1988 M5 (E28) 92K
1988 M3 (E30) 36K

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