2002 Chevrolet Corvette Long Term Road Test


2002 Chevrolet Corvette Z06: Pinging At Full Throttle

January 19, 2010

vette-100oct-done.jpg

Z06: Knock, knock.

Me: Who's there?

Z06: Detonation.

Me: Oh, s#&@.

Two days after he picked up our longterm 2002 Corvette Z06, Senior Editor Ed Hellwig thought he heard engine knock at full throttle around 4000 rpm. I took it for a drive and confirmed that, sure enough, it was definitely detonation Ed was hearing.

The previous owner didn't pile on the miles. We figured maybe the fuel in the tank was old and had become octane-deficient. So we ran three tankfuls of fresh 91 octane through it. It made no difference -- the Z06 still pinged like crazy.

We brought it to the dealer last week to have them check into it. They reflashed the ECU with an updated calibration and separated us from $98. Again, no difference.

At this point we thought maybe we were nuts. To be doubly sure that what we were hearing was in fact detonation and not something mechanical in nature, we added octane. Yesterday I mixed five gallons of 100 octane with the few remaining gallons of 91 still in the tank. The pinging vanished.

We'll bring it back it back to service once all the 100 octane fuel has been replaced with 91. Maybe this time they'll check the timing and verify that the knock sensor(s) haven't crapped out.

It's anyone's guess as to how long the engine has been running in this state. Though it runs strong according to the ol' butt dyno, a basic compression and leakdown test would be a good first step in determining whether prolonged detonation has caused any engine damage.

Jason Kavanagh, Engineering Editor @ 42,340 miles.

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