Question have a 1990 Oldsmobile Cutlass Calais S, 2.5 4 cyl tbi. The following started all of a sudden and has not changed since happening. It has a rough idle and almost stalls when trying to accelerate from a stop. Backfire in motor or through throttle body with or without load when revving motor on occasion. The motor does appear to catch and run better when going through the rev band somewhat but no consistently.
The tech did the following without success in diagnosing the problem, diagnose and scanned for codes, no codes found, ignition system looked good on scope, fuel pressure is good, all scan data looked good. put in new plugs, inspected plug wires for problem none found. The tech was frustrated (so was I) after 4 hours of trouble shooting and not solving the problem.
He had the following ideas about the problem, coil pack, crank sensor... Please help !
Thanks
Mark
AnswerThe 89 and 90 2.5L intake maifolds had design problems and there were numerous repair procedures recommended by the manufacturer to correct the problem. If your tech noticed, that on the 4 spark plugs 2 of the plugs wer burning differently at the electrode ends.
check with your dealer as they received numerous TECHNICAL SERVICE BULLETINS for this problem.
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