1982 collectors ed. 36k miles. 5 years ago I changed exhaust to dual with no converter. Changed the chip to hyper tech. Advanced the timing a few degrees and run premium fuel. Car ran fantastic. Maybe 3 years ago replaced fuel pump to '85 model and rebuilt fuel regulator and set pressure to 14 I think. Sat took car to car show where it rained a good part of the day and found the rear hatch leaks as the carpet is wet. Car ran fine all the way home, about 35 miles. Last night was going to a cruise in and it was surging then misfiring. Turned around to go back home. Stalled 2 times and ran like crap all the way. Today checked the codes and there was a 15 and 43. Took the ecm out to check for water damage and all looked ok. Even the factory GM remanufactured sticker looked good. Must have been replaced before I got the car. Put it all back together, started it up and it runs great again. Ran it for about 20 min. Have not driven it yet. Any ideas? Huge Corvette show on Oct 1 that's about 40 miles away so I need it to be reliable.

 

I would drive it around town a few times in the mean time to ensure its good at this point... how much has this car been driven since last years car show? that might be your issue.. how old was the gas for example?

 

Half tank of gas in it now that's maybe 2 weeks old. I know I need to drive it around but want to check everything I can before I do as it's all 2 lane roads around me with no place to pull over if it stops running.

 

15 is coolant temp high. 43 is electronic spark control. other sources say 43 is knock sensor. let's hope not. knock sensor is a difficult fix.

 

I do not think at this point the knock sensor is the issue, but it could be. Did you follow the troubleshooting steps on page 6D-27 in the GM service manual to determine the problem? Also use page 6E-46 for the code 42 and page 6E-40 for the code 15. If your ECM is bad, I can help you out for sure. PM me if that's the case. GL

 

For certain find some time to drive this thing around. Even if it's just around and around the block you live on.
Sometimes just unplugging a ECM and putting dielectric grease on the terminals will correct a issue with a poor connection.
A RELIABLE C3? Please.

 

Hello there 4-vettes,

I assume that you are aware that Die-electric grease is NOT CONDUCTIVE and will impede the electrical flow through contacts coated with it. You should never put Die-Electric grease on critical connections, not even on battery connections. They do make grease that is conductive like the materials used on battery connections. DO NOT put die-electric grease on any wire connections, especially not the wires going to your ECM or you will introduce new problems to your Corvette.

More problems have been created with Die-Electric grease as many people are not "aware" that it blocks the flow of electricity and is non-conductive. Die-electric grease is used to make getting the spark plug boot off the spark plug easier. If you put too much inside the spark plug boot your spark plug will not fire.

Here is are a couple blurbs about Die electric grease I found on the web:
1. Does dielectric grease conduct electricity? No, it does not conduct electricity. Even if it is used at points of electrical connections, it is incapable of conducting any electric current. Instead, it acts as an insulator and protects your connections from various agents like moisture, dirt, etc. Additionally, dielectric grease can also provide protection against corrosion.

2. Dielectric grease is a non-conductive, silicone grease designed to seal out moisture and, therefore, prevent corrosion on electrical connectors. Being non-conductive, it does not enhance the flow of electrical current.

3. Dielectric, sometimes referred to as tune-up grease, is a viscous non-conductive waterproof substance used to protect electrical connections from corrosion and dirt.

If you really want to clean your electrical connections a standard pencil eraser can do wonders, if you want high tech then try some DeOxIt and wipe it on the connectors. DeOxIt removes the corrosion allowing for an awesome connection. I wish I had some DeOxIt when I owned my British and Italian motorcycles......

"A RELIABLE C3? Please." This I personally find offensive, I have 2 Corvettes and they have both proven to be great cars that are reliable and a pleasure to drive.

I have had a C3 since 1991 and that Corvette has never left me stranded or stuck anywhere in the time I have owned it. Like anything mechanical it does require a bit of work but in the end it has been a very reliable car for me. My other Corvette is a 1988 with the L98 and it's TPI fuel injection system and it too has been a great and fun car to drive. Understanding how to maintain them and doing the routine stuff does help but the design is good and they work reliably for me and my family.

 

I changed the 40 year old coolant temp sensor with the newer style. Did all the test recommended and all is ok. I even set the tps at .530. Let it run while I hosed it down after adjusting the rear hatch to check for leaks then took for a drive. Running better than ever. Thanks to all that had constructive comments and recommendations. They are always appreciated. This is not my 1st C3 and all others have been very reliable as has this one. This was just a minor glitch. It's not like an '05 that I know of that would not start for a year 'till someone with the correct computer connected to it and found a bad power window switch. Now if I could get the tach to read correct instead of 400 rpm higher than it is this car would be perfect.

 

If your hood was open during the storm that moister can creep into the distributor cap and todays China made crap instantly starts to corrode. That could trigger the knock code and make it run all crazy, as the moisture turns to steam under the hood. Your ECM in the back is pretty well protected but a hot steamy car pretty much puts moister everywhere…including the ECM eventually if you can’t dry the car out. My advice is definitely pop the distributor cap and check for corrosion.

 

Hood was closed. Only place to get wet was carpet behind the seats and battery box was a little wet. That's why I took the ecm out to check it.