So I just bought my first ever corvette: 1995 Competition Yellow Corvette Coupe. It has 78,000 miles on it and is in wonderful condition. I am using this car as my daily. Saying this, I have a hesitation/stutter in both the idle and while on load. After searching and reading multiple posts and talking to friends and mechanics, it seems to be an ignition problem. Most suggest the suspect is the optispark. I am a 20 year old college student trying not to break my bank, but I understand that I should go for quality parts when doing corvette work. I am pretty amateur when it comes to working on engines, but I would love to and am willing to learn hands on. Looking at this thread: http://forums.corvetteforum.com/c4-t...-pictures.html I believe that I could do this job myself with help rather than just paying a shop. All in all, I plan on replacing plugs and wires, the water pump, and the optispark as well as any hoses that need replacing. So, my question is, is this job feasible to take a weekend or two doing while driving a different car? Also, which brand name water pumps and optisparks would y'all suggest? Any help is appreciated.

 

You might want to troubleshoot a little before taking on an optispark install. First, spend your money on a Factory Service Manual. They sell on Ebay for less than a $100. It could be many things. Plugs, spark plug wires. But going down the troubleshoot list can eliminate many items. Have you pulled the codes? That would be the first thing to do.

 

Okay, I have not had the chance to pull codes on it. I am not getting any check engine lights. I just got a service manual and have begun to troubleshoot. After talking to more people and experiencing the problem even further, my next step is to clean the throttle body and put a new fuel filter on. I will be doing that hopefully either today or tomorrow. From the evidence, I am thinking it is more of a fuel related issue.

 

That is an excellent call.. With 10 percent ethanol in fuel these days, replacing the fuel filter needs to happen more frequently due to alcohol's propensity to absorb moisture. The C4 fuel filter is technically called a fuel filter/water separator. I try to fill up my car at freshly stocked gas stations for this reason.

 

Anyway, the FSM has a troubleshoot procedure for the optispark and could save you a lot of money and grief.

 

95 thru 96 are the more reliable vented setup. Surprising that you are having problems.

Be sure to check both vent hoses and make sure they are ok.

Prob just needs a new cap/rotor (still will take you some time).

Or maybe if you are real lucky, just spark plug wires.

also, if thats an oem optispark...dont dare send in that core because those are the best ones ever made.

In fact, if someone has an aftermarket non new old stock opti in there then that might be the reason why its giving you problemS. The non -oem units do not have a good record of reliability.

If you have to buy one, delphi seems to be the most similar to oem. You really want one with a mitsubishi optical sensor - though they are hard to find.

Personally, if i bought a delphi, took it apart and found it didnt have a mitsubishi optical sensor, id send it back.

All this said, there are guys running other optisparks And some are doing fine. i myself got burned by an ac delco 'rest-assured, remanufactured unit'. They did a great job replacing bearings, seals, etc. But they 'recycled' the old units optical sensor by spray painting it black and called it new. Nothing is worse than having to go back in and re-do the job. Thats what i had to do.

If you can find a used new old stock optispark, thats better than the crapo options out there

Also, dont replace the waterpump if its working fine (the replacements are rebuilt to$h1tty standards in china). However, do add a weep hole mod to direct any leaking coolant away from your optispark.

Welcome to the c4

 

Okay, so I replaced all my filters and my plugs and wires and am still having my problem. So, this last weekend I took it to my mechanic and we did some troubleshooting for a solid 3 hours. We determined that it was, indeed, misfiring. We started by checking the injectors. Bingo. They were not pulsing consistently and the resistance for each injector was all over the place. We then hooked up the OBD I scanner and it was showing a "Code 18: Injector Circuit" code. Each injector had 13 volts running to it, but the ohm resistance was all over the place.
So I am putting a new set of flow balanced injectors in and crossing my fingers that the old ones didn't damage the computer. If the new injectors haven't quite fixed it, the new computer comes next.

I'll keep you informed as to what fixes it!

 

The lesson here: Pulling the codes should have been the first thing you should have done. Auto*one will loan you a scanner for free. Like my Grandpa use to say. "You can lead a horse to water*****+++."

 

Fixed! So I put new injectors in this last week. After putting the replacements in, there is no longer a misfire. Runs so smoothly now! I also ended up putting a new radiator in due to a newfound leak. She's all good to go now. And yes, I should have pulled codes first...lesson learned!

 

Glad to hear you got it fixed. A common problem on late model Corvettes is the spark plug wires that dry and crack from the heat so replacing them was not a waste of money.