Cadillac Seville / Cadillac Eldorado Forum Discussion, 98 STS misfires. Pretty badly. Unless it's raining. in Past Cadillac Vehicle Discussion; My 98 STS is misfiring constantly. Does ok at constant highway speed, but under load it bogs right down. Very ...
Pull the coils off and see if there is any signs of arcing on the underside. Listen to them with a stethescope while idling. If they are arcing internaly you should be able to hear it. As a last resort, borrow a coil from another car and swap them, one at a time to see if, and which one will make a difference.
Last night I changed the coils and re-seated the map sensor, which may have been askew. It's running pretty good, but then again, it's still raining.
There's still an occasional miss. I really don't think I've found it yet.
Map sensor is $60, MAF is ??. EGR valve is probably in that mix somewhere too. This is getting costly, and aggravating. I may actually have to take it to a shop.