I recently purchased an 04 conv. the car had 2900 miles. I have had a constant problem with the valves pinging under any type of acceleration. not real loud in fact you could only hear it with the top down, I have taken it to the dealer and was told that it was a problem with the gas, recommended either shell or marathon. should I use an octane booster? they did a computer check and said everything was ok! I have had about 3 tanks of shell 93 octane and the problem is still there, any comments would be appreciated!

 

Its not valve pinging, but pre-donoation (pinging) I think. When this occurs you can blame it on "poor octane," but assuming you are filling up with premium it should not happen. Other problems (poor tuning) can cause detonation (pinging).

You could do an experiment: put in a bottle of octane booster once to see if it helps. But you should not need to use it if the car is stock. The timing or fuel delivery could be off . . .

I would have the car properly tuned - and not at the dealer. Ask around for someone in your neck of the woods that has a chassis dyno and an engine tuning capability (a program called LS1Edit or its equivalent) They can run the car under load and monitor how it is running, then edit the engine computer to set fuel-air and timing precisely. Among other things you will not only have the car running well but probably pick up 5 HP or so in the process.

I am assuming you car is stock, but if it has been modified at all (headers, etc.) then it is even more urgent that you do this.