Rdorr6

I have a 94 Lt1, I have Been having erratic performance, from good when cold to lousy when hot. It seems to run good for an hour or more then performace drops off and becomes erratic, it sputters , misses and loses power. It seems to be worse at lower RPM's And clears over 2000 RPM, At the same time the clutch chatters in 1st gear. This symptom can come or go, ex: I can drive for an hour and the engine starts missing and stuttering, I can turn the engine for a few minutes and it may run good again for a while. It's getting pretty aggravating. I had the Opti and plug wires replaced 5 mos ago, since then my water pump went, I caught it right away(it would miss occasionally before water went). Recently out of frustration I relaced EGR (it ran good one whole day), both O2 Sensors,I found what I thought was a bad plug wire(plastic tubing was melted over wire) and replaced it. The car only has 30,000 miles on it. Any help would be much apprieciated.

Dan Oldham

Hmmm, sounds like a pretty strange thing you have going on there. I would immediately tell you it was the optispark, but in the case of the optispark, the car would be missing all the time.

My first suggestion would be to make sure that all the plugwires are making full contact, and to make sure none of the wires are burned.

Second of all, I would check your TPS (Throttle Positioning Sensor), due to the fact that you stated that the car seems to be sputtering out under 2000rpms, and then straightens itself out. Normally, when it's a TPS though, the TPS will send an extra signal to try to compensate for the failure, therefore trying to stop the car from stalling.

If your car is missing and stuttering, and then you turn the car off, and then back on again, I would also inspect the PCM. Get a screwdriver and tap the PCM with the screwdriver handle lightly (or a rubber mallet) and see if the idle jumps and sputters. If this is the case, your PCM is bad.

Check the fuel system, and even buy some fuel injection/throttlebody cleaner just "in case" there are some gas deposits causing your problem. This is probably unlikely, but when diagnosing problems yourself, pull out all the "easy stops" yourself.

As far as clutches go, I can't really give you any advice on them. I don't have a clutch in my Camaro. However, is it possible that the clutch could be sticking or something, causing your car to sputter out?

I've never heard of this problem that you're experiencing. I wish I could be more help, but, I can only tell ya what my suggestions are.

Good luck with whatever is going on, and once you get the problem (s) resolved, make sure to post the results.

mirroredfire2

if you have a K&N filter or even if you don't id make sure the MAF is clean.. and a cheap thing that has fixed this for some people is changing the IAT sensor its just a sensor in the left side of the throttle body and should be real easy to change and its only 10 bucks.

Rdorr6

I still havn't found the problem, runs great for about an hour then it starts to sputter and miss, engine sounds like the timimg is retarding. I plan to change plugs and wires, if that fails I,ll try to get it on a dyno to see if I can isolate the problem. Is it possible to be an injector, do they missfire when they get hot?

JB'z 94

I am actually having this exact problem with my car right now, but it has gotten much worse as time has went on.. It, like your car only does it while running hotter. I took it into the dealership just recently and they said they couldn't do anything for me until it got worse.. I am going to try some of these suggestions and hopefully it will be alright.. thanks and good luck Rdorr6

Lyle A

Heve you guys tried scanning your PCM for codes? It might help if you have a sensor problem.

Rdorr6

I set up an appoinment at "Mr Goodwrench", Classic Chevrolet, Moorestown, NJ, It sat there all day and they never looked at it, maybe c because it was a comeback. Anybody know anybody good in diagnostics in the S Jersey area!

Rdorr6

Is there any way to test an Opti off the car?

Lyle A

Not that I know of. If I was going to go through the trouble of removing the opti, I would just replace it.

Rdorr6

Thanks Lyle A

Rdorr6

I have a spare opti, I replaced the first Opti in March

Lyle A

You know, I have a 94 also. I had a similar proble. The funny thing is, so have just about everyone else. I have a friend with a Snap-on scanner so that helps. I found a bad O2 and since I had the car off the ground I replaced both and the fuel filter. The car ran better but still had a little problem when it was hotter. I installed a fan switch and quit buying the cheapest high octane fuel I could find. I ran injector cleaner and use nothing but Union 76 fuel. She runs pretty good now. With 30,000 on your car, I doubt it's the opti. Alot of people replace them without actually fixing the problem. I would look to the coil or Ignition module first. Scanning the PCM could lead to the solution quicker. Good Luck.

Rdorr6

Thanks Lyle A

JB'z 94

The dealership scanned it and no codes were thrown..

I was also thinking it could be an O2 sensor somewhere, contributing to the problem, I just need to get my butt in gear and fix this now

Lyle A

A faulty O2 will throw one of several codes. I don't trust dealers too much. I'm thinking about getting my own scanner.