: Running rough, really baffled

12-12-04, 01:26 PM
The problem I'm having is that at idle and WOT, the engine runs fine. At light/part throttle the engine runs rough as though it's miss firing. This first started when I reinstalled the engine the first time and thought that perhaps I had dirty connectors on the wiring harness or something just wasn't connected correctly. I had just installed new wires & plugs, both were AC Delco from the dealer. When I had the engine out this last time, I took a couple days and went through the entire wiring harness, did a continuity test through the whole thing while moving the connectors. I spent a few hours cleaning every connector and retaped the entire harness. I cleaned every switch/sensors contact pins as well.
I've been through the service manual and have done all the ignition tests and everything checks out fine, no codes set but the miss still exsists. I hooked up an inductive timing light to make sure the plugs were firing and what I found is that at about 1200RPM and up the light would cut out showing me a serious miss, this was the same on every wire. I'm suspecting the ICM,but those are about $230 aftermarket and I can't afford to go get one just to try it out. Is it possible for all the coils to go bad at the same time? Other than this problem the car is tip top.
If any of y'all have ideas I'd love to hear.

12-12-04, 01:51 PM
I've spoken to a mechanic here in England and he suggests it could be one of your coils going bad, if the ICM goes, it usually goes completely and the engine does not start at all,
Maybe you could get some coils from a junk yard just to try out as the coils are easily accessible.