I own a 1998 3.8L Camaro. I've replaced all three coil packs and spark plugs and plug wires within the last 12 months and have had perfect driving ever since. About three weeks ago, I noticed a stumble or hesitation in minor acceleration. To date, it misfires only during acceleration. Sometimes it will act up for 30 miles, some times it will miss once during an entire 30 mile trip. It's hard to predict. I've noticed that it's worse when I run it cold. When the coolant temp is up, I tend to hear less misfires.

ANY suggestions? I've racked my brains trying to diagnose this problem!

EDIT: After searching past posts, I've noticed a lot of talk about failure of the ICM. How do I go about checking the ICM to indeed clarify that it's the problem?

 

Start by changing your plugs again. Is the check engine light coming on?

 

Yeah, I get a P0300 code. I had the module tested at a local AutoZone and it passed every test about fifteen times. I can attempt a plug/wire change, but I really would like for some sort of explination as to why a plug/wire failure would only effect the engine during acceleration. Ideas?

 

timing chain

 

I highly believe that if it were my timing chain, it'd be missing almost constant. Not here and there. Looks like I will change the plugs and wires this weekend.

 

could possibly be the ignition module. it would not be throwing a code tho. i don't think the ignition module is part of the computer circuitry. Sick

 

Correct, but no. I had the module tested at a local AutoZone and it passed every test numerous times.

 

This may sound stupid, but it may just be the fuel filter. Same thing happend to me, and after changin everything a guy at the post auto care told me to change it. Worked great after that.

 

is the p0300 the only code setting? did you check for vaccum leaks? have you replaced the crank sensor if so my manual says you have to perform a crankshaft position system variation learn procedure anytime the crankshaft position sensor is replaced,pcm is replaced, crankshaft balancer is replaced or crank shaft replaced or it could set a p0300. the first set of checks says to check secondary ignition wires and then coil packs, i know you replaced them but dosnt mean one hasnt went out already. also i would check my grounds especially to the icm. i am pulling this info from a actual 1997 gm service manual for 1997 camaro and firebirds. let me know if any other codes are set and i will try to help with the diagnosing best i can without actually being there.

 

A good explanation of the P0300 code (an A level code) can be found here: http://www.obd-codes.com/trouble_cod...e-detected.php

Straight from the factory: http://service.gm.com/gmspo/mode6/pd...c38K_CFHWE.pdf

I don't know if the scanners that Autozone use read multiple codes or GM enhanced codes, but you also might be throwing a P1404, an EGR valve malfuction, not fully closed (a B level code). This would cause a lean condition and cause a stumble under light load.

I'd go with Z's advise and change the plugs. Also have a complete scan done, including GM's enhanced codes.