This problem has been plauging me for over year now.

It's a 95 Aurora with the Autobauhn package. I have replaced the wires and plugs with AC Delco OEM parts twice now. I have also replaced the fuel regulator and idle control motor.

But here's what it does. It has a slight miss...really slight...at idle. But whenever I put a big load on it like going up hill, the miss gets REALLY bad and the whole car shutters. I have to drop it into 3rd or even 2nd sometimes to get the RPMs up there to mask the problem. It never stalls though no matter how bad the shuttering gets.

So in short, it has a miss at all speeds and gets more notiable as the load increases on the engine.

I have taken it to the dealership once and that's when the fuel pressure reg. and sparkplugs and wires were replaced....that fixed the problem for EXACTLY one month. So I replaced the wires and plugs again, but it did nothing the 2nd time around. So I replaced the idle control motor which also did nothing.

Oh yeah, and no SES light and no codes in the computer.

Any ideas?


Thanks!
M

I would find out if there is a way to check the voltage output of the coils UNDER LOAD. This may mean finding a shop that has a dyno and the diagnostic abilities. Sometimes you can recreate it by putting it in gear, with your foot hard on the brake, and throttle it a little. But the key is "under load"! Resistance can reveal weak or defective areas even with new wires. I have seen plug wires arc together only under load, just barely touching each other. You definitely have a hole out, maybe two, and continued driving when it's that bad is going to hurt something. Abscence of SES light could just mean a sensor malfunction, but it is missing. A new coil pack may be worth a shot. You can do it yourself in a few minutes and they are cheap.

Thanks Indy, I never thought of the coils...they are the original with 127k miles.

Thanks!
M