I own a '93 LT1 stock with 24K miles. Just purchased 7 wks ago and it was running great on my ride (70 miles) from the dealer. It has been stored since then and just started for 15 minutes each weekend (+-) when I noticed that it began sputtering and popping after the engine was warm. I was told by a mechanic that this was the best shape he has ever seen a car that was 11 years old (not a speck of dirt in the engine compartment so I would imagine that the last owner was quite meticulous. Any ideas what could cause this phenomenon? To elaborate, I ran a scanner and there were no faulty codes. It runs great when it's cold but when the temp reaches 165 degrees, a rev causes a backfire ( I think midway through the exhaust system?) If driven it shakes on full throttle and bucks from the misfire. The idle becomes erratic and the dash lights dim from the drop in RPM. I have the other readouts if any are helpful. At this time I am looking at what the normals for these readings should be with hopes of isolating the responsible system. Others have said it sounds like condensation caused excessive water in the fuel. I may buy that but before I go dumping 16+ gallons of hi-test I want another opinion. Have added Heat a few times but no change in the problem. All new filters but am holding off on the fuel filter until I decide if I will be siphoning the fuel.
Any help is totally appreciated..spring is around the corner and I want to get this badboy out and cruise!

 

Try some Sta-bil gas treatment AND a fuel filter. If this doesnt help, re-post.

 

Moisture in the opti?

RACE ON!!!

 

That's what I'm thinking. If the engine compartment is so clean, perhaps the seller was a little too liberal with the water spray...

 

OK, I can appreciate the thought that the dealers detail guys got overzealous. The "OPTI" is that referring to the ignition module...optispark?
I was going over the Vette Service Manual and it makes reference to the fact that the Air Control sensor should be reading "Divert" on the scanner after about 240 sec when the ECM takes over the air control but mine continues to read "PORT" for many minustes past that. My reading came after 8 minutes and still "PORT." Could it be that the Air Bypass SOlenoidis involved here and that what I am hearing is detonation of fuel in the catalytic coverter? I don't know and will try adding the stabil and changing the fuel filter to see if it helps out. Is Stabil still good after the fact? I know that the tank was around 1/4 full when I viewed the car in the showroom. It was stored indoors in the showroom. The dealer filled the car the night I was supposed to pick it up.
Thanks for the help thus far..oh ya, could you elaborate on the OPTI part. I am brand new to Vette lingo and am thinking Bill Gates is responsible for some of these acronyms!

 

I researched an article online about the OPTI and found the following information about removing and assessing the condition...the following link gives a mod on the OEM OPTI... http://www.corvettefever.com/howto/16758/

I imagine this is what you are referring to?