As a back story, when I got my '93 it wouldn't run more than just a few minutes at a time. narrowed it down to the optispark being the issue so i replaced the opti with a new cardone from advanced with a lifetime warranty. After replacing the opti the car ran good, but had a slight miss at 1k rpm or so but smoothed out by 1200 rpm, but otherwise it ran very well.

Today i had to run a few errands so i figured it was a beautiful day and I would drive the vette. Got about half way to the store and the car developed a hard miss that happened everytime the a/c compressor kicked on. I turned the a/c off and the problem persisted. I pulled over and shut the car off and let it sit for a minute, turned the key and she fired right up as if nothing was wrong. Started to accelerate back up to speed and she was bucking like crazy and the tach needle was all over the place, which to me seems like that would be an ignition issue. went into the store got what was needed came back out and sweet talked her and she fired up and ran great the whole way back home ~15 minutes.

Some family came over for mothers day and one of my nephews wanted to go for a ride so we hopped in the vette and started off everything seemed fine but all at once she shut down but fired right back up, turned around and started back for the house and she shut down again, but didn't start back up right away. after about 5 mins or so she fired back up and again, ran like nothing ever happened. Got home and let the car idle in the driveway for almost an hour and she never missed or anything, but put it in gear to pull into garage and she shut down again but cranked right back up.

Did this opti go belly up just all at once? No codes are stored, check engine never came on but i checked anyway. anybody know where to by a NOS gen 1 opti?

 

TTT

The tach was all over the place on the way to work this morning, exhaaust doesn't sound right either.

 

sounds more like poor grounds and other misc electrical connections...
Check and clean ALL your power connections at or around the battery. There are several that are NOT on trhe battery pos post but somewhere else thats split up to several wires...near or by the battery.

 

I have checked all ground connections and all were clean. What seems odd is after yesterdays episode it now has a miss at idle, has always missed at exactly 1k rpm but that is worse now. The idle is at different rpm's sometimes it idle at 650 and sometimes 1500. It has a new IAC and that seems to be working properly.

 

Did the opti get wet recently from puddles/washing or have you had heavy rains in your area and filled up at a gas station that could have got water in their bulk tank. If the answer is no, check the opti harness connections and the connectors that go to the coil. Could be loose connector or chaffed wires going to the coil or opti. Coil could be heating up opening the windings, I'd take that and the ICM to be tested at a parts store before shotgunning expensive parts. Unfortunately intermittent electrical problems are the hardest to fix until something finally craps out.

 

car hasn't been washed in almost a month, stays wiped down and clean. It was raining pretty heavily about 2 weeks ago when my exhaust was done, but i would think that would have shown up sooner as the car is driven a lot. It was filled up Friday a week ago, and i guess that could be a possibility but my wife filled up at the same time from the same gas station using the same grade fuel and no issues in her car. on the way home from work I noticed it misses a lot at idle, I ran it up the RPM's at one point and had to pull over, once it got to almost 5k it backfired and cut off, but started right back up. I am lost on this. I did change the coil and icm when i did the opti, I will throw those back on and see if there is a difference.

 

This is indicitive of a bad Ignition Module located on the front of the passenger side cylinder head. These are gel based and can go bad without any warning. The tach will bounce all over when this goes bad as it is part of the circuit that the crank sensor is on. Replace this and it should fix the problem. Usually can get this part at O'Reilly for about $100 or the dealership for $140.

 

On the passenger side of the Intake manifold, you will see a Connector that feeds the Optispark pigtail. Check for any corrosion or intermittent issues there

 

My original A/C Delco opti caused a similar problem to yours. It started out as a popping like it was on the revlimiter when rpms hit about 5500 rpms, just before shifting. As it got worse, it developed a miss from idle to 5500rpms. Later it just died and wouldn't restart. My second opti was the Cardone. It lasted 2700 miles. It ran fine for 2650 of them, then it too developed a miss or better yet it felt like I was hauling a trailer. Then it got to the point that when the engine heated up to running temp, it would just die like the key was turned off. The high resolution signal was lost to the ECM killing fuel and spark. I'd give it 20 or so minutes and it would start right up after cooling down.

I have no love for the Cardone brand but I'd give it the benefit of the doubt and check all the wiring from opti and coil. Then I'd change out the cheap and easy stuff like ICM and Coil before tackling the opti.

 

And Good luck hope it's a quick fix.

 

Any luck finding your problem?