69mako

The Vette:
1994 Coupe. LT-1 automatic trans, 151,000 showing on the clock.
No engine modifications, 10 year old opt spark (was good when I pulled it off) reinstalled this spring when old opti crapped out.

The problem: Took her out tonight after sitting on jack stands for six months as I rear built the rear suspension. She ran great the first part of the 10 mile trip to the gas station -extremely strong. I stopped at a Sunoco and filled the tank (it was a 1/4 full) with 93 obtain super.

I drove back home about 7 miles and while I was stopped at a light the engine started to surge in the revs -jumped up about 300 revs from idle and studdered some as I pulled away from the light. Made it home and parked her in the garage. In park she would jump up about 300 revs and drop back down. AC on and off it still had the problem. It occurs in while in drive and in park, and it is intermittent. -No check engine light.

Tomorrow I will put a vacuum gauge on the EGR valve, and see if that has a vacuum leak and look around to see if anything is disconnected or burnt. I'll also pull the plugs to have look at them.

I believe the gas at the station was good (Sunoco), because the problem did not immediately show up after the fill up and that some engine management sensor or the opt is ready to crap.-I could be wrong....oops

-What do you think?

Thanks, Larry enjoying a few cold ones right now

valiant68

My 92 done the same thing, it was the ecm at the left of the firewall, I bumped it with my palm and it cleared up, I later took it to autozone sent it off and rebuilt it, it hasn't missed a lick since.

69mako

Got down to brass tacks this evening and pulled the codes. C-12 and H-16 are what showed. I know those codes,-came up the last time my opti died looks like its time for a new opt-spark.

While I have my head in the engine bay I'll also replace the O2 sensors as they have some time and miles on them, and a new set of plug wires would be a good idea, this set has ten years on them.

valiant68

I guess I'm lucky, I haven't had to ghange my opti yet, I dread that day lol

valiant68

What is a good brand opti spark if I ever have to buy one?

69mako

I went with an Opti spark from Zip Corvette Products at $179.
I wanted an OEM ACDelco opti, but the prices are "Good golly miss Molly" expensive at $500 plus a core charge of $75...Ugh.

The opt and new wiring harness for the unit will be installed this weekend