92 RS with a 3.1 V6 and 5-speed

It only does it after the car warms up. I can feel it getting a bit weaker and lacking power slightly, right before it starts backfiring and stumbling.

It only does it if I rev it above 3 grand or so. One time it got really bad, and I couldn't take it above 1500 RPM, or give it any gas whatsoever. I drove home at a top speed of 30 MPH, and it took 10 minutes to get going that fast.

If I leave it alone, I can drive until it warms up fully and stays at temp for awhile, but then it starts doing it again.

It has a new coil. I'm going to grab an O² sensor, and suggestions or ideas would be helpful.

It's so intermittent and unpredictable, I've even had fleeting thoughts of it being the ECM.

 

it wasnt the O2 sensor... it still does it

any help?

thanks

 

Have you checked to make sure your PCV valve and Catalytic converter isn't clogged? If you haven't, do it. If the cat is glowing red, you just found your problem.

 

its been a year since i changed it, but i pulled it out and checked it anyway, and the PCV valve is fine. the cat isn't getting unusually hotter than the rest of the exhaust at all. the car sounds good too.

this thing has me stumped...

I'm seeing quite a few other guys on here with what I think is the same problem. none of them can figure it out.

i'm just going to test everything i can test today, see what i come up with.

 

Don't laugh when I tell you this, because it actually happened to my friend. When the motor was cold, it would run fine, but when he'd driven it for a bit at operating temp, it would mysteriously start sputtering and losing power. We tracked it down after a couple of days. It turned out to be a cracked ignition module on his distributor. One of the wires was a little frayed too, so we fixed that when we replaced the module. And voila! The problem went away. Just a thought.

 

I'll second having the ignition module tested. When replacing it (with new or old) make sure you clean it and the base well and don't use dielectric grease, use the correct white paste.

 

i'm going to check the ignition module today then. i think one of those things are 60 bucks around here though... so i'll have to wait until i get paid to pick a new one up if that's it.

any other suggestions?

im hopeful for this though, because it really does seem like an ignition problem to me, although i have no hard evidence towards it.

i'll keep posting back so hopefully we have a topic that resolves one of these problems.

thanks guys

anyone know a way to test the ignition module???

off to "search" i go

 

Autozone should be able to test yours if you take it in to them.

 

Electronics (of any kind) can get flaky when they get hot. The module is only one thing that could cause the problem- and it's certainly not going to be 180* when they put it on the tester! The magnetic pickup and the coil itself are other things that can have heat-related failure.

I had a coil just a couple years ago that worked just fine when cold. And even when hot. But do a good 10 second WOT run on a hot motor and it would shut off for about 5 minutes once you let off the gas- no sparks at all. Turned out to be a flaky coil, despite the fact it passed bench tests. Dropped in my "known good tester coil" (a coil I ripped of a junkyard car) and it ran like a top.

Junkyard distributors, coils and such are not what you want to go racing with but they come in very handy when troubleshooting an ignition problem. And they cost tons less than new parts.

 

oops, double post

 

it got a new Accel coil in december due to the old one dying. It acts alot different than it did when that died

i unplugged a few sensors one by one... most would change how the car ran, but it still had the problem.

the MAT and EGR had no change in the car though

i didn't have the ***** to pull the MAP, thinking maybe i'd have to reset it somehow if i did

the car has had a new fan relay, new CTS, new coil, cap & rotor, and O² sensor. I replaced alot of questionable looking vacuum lines (the car idles a lil high normally anyways) and no change. it pulls good vacuum at the hoses, but i haven't put a gauge on it.

my EGR plug wires are looking a lil crispy and frayed, i'm gonna try and patch those up, see if there's any change.

i'll take the ICM to autozone in the morning

 

Just wanted to post back and let everyone know the problem.

It WAS the ICM. When I pulled it, the heatsink grease underneath was cooked to all but non-exsistence. It looked to be the original piece. I put a new one in, and used some better heatsink paste than what appeared to be there before, the car runs great.

In addition, changing the plugs, wires, O², oil & filter, and air filter while trying to find the problem netted me another 6 mpg on my last tank!!! lol

I was rather suprised

thanks for all your help you guys