When I first start it in the morning, it runs fine for about 30 minutes or so. Then it gradually starts to stutter and shake when I push the pedal to about 1/3 throttle or more.

I just replaced the spark plugs and wires yesterday and this problem seems very stubborn and won't go away.

When I say stutter, I mean shaking pretty hard, I lose horsepower and acceleration. I can cruise, but anything past 1/3 throttle makes the car shudder and shake pretty bad.

I am not getting an SES light, what can I do?

In a nutshell:
Car is shaking and stuttering when I give it more than 1/3 throttle, is this a misfire?
Since I have no SES light, what can I do?

 

it sounds like a missfire, did you check your coils when you went to install the plugs and wires? And if it is a true missfire obd-2 should thow and SES light but are you sure you SES light is even working? The blub might be burnt out. Next time when you get in the car turn the key to the key on engine off position and see if the SES light comes on furing the bulb check. But I say take it down to auto zone really qucik and just get a quick scan too see if there are any codes in the computer.

 

Oh yeah, the bulb works, I had an O2 sensor fixed about a month ago cause it was on for a long time (and I just checked it, it works). What do I need to check the coils? Just take them apart and check them? I haven't done much engine work, so I need all the info I can get. Thanks, crasher.

 

I have found the problem. The ignition control module failed miserably (only passed one of 7 tests) and needs to be replaced. When I buy one (a week from Saturday unless I can bum some cash from my dad until then) I will redo the wires, as they are crossed and tangled.

Another question: It is now misfiring at idle, it didn't do that before, it sounds like the LS1 piston slap almost exactly. Is it a bad idea to drive if it is misfiring like that? It quiets down when the A/C is off, but doesn't disappear completely. I know I am losing more gas than normal with a misfire, but does it put my engine at risk to drive it while there is a misfire?

 

I personaly won't drive it on a misfier but in the short term i don't think it would probably damage the engine much but say if you drove around with it missing for like 6 months or so I sould say for sure you have taken quiet a few miles off the engine. I think as worst you will be sending too much fuel into the exhaust and might foul out the O2 sensors or possibly shorten the life of the cat slightly but other than I that I doubght you will cause any major problems.

 

If anything it may foul the plugs and the O2's, so for short trips, its prolly OK. DONT get on it tho.