2002 Chevrolet Corvette Z06: Dealership Woes
February 10, 2010
By now you know the story behind our 2002 Chevrolet Corvette Z06 and its engine knock. We dropped it off at Cormier Chevrolet as a starting point, expecting the Corvette-centric dealership could mend our ailing LS6. We expected too much.
Office chatter on the day we picked up the Z06 went something like this:
"Is the Vette fixed? What did the dealer say?"
"The tech drove it while hooked up to his computer. He recreated the ping but even at the moment of detonation his equipment showed no signs of error. The knock sensor did not relay a fault. The tech elaborated. He said this ping was an issue he'd seen on numerous occasions and would consider it characterisitc of this engine. Some are cured by the ECU recalibration we had. Others are not."
"Screw the dealer. They are apparently completely incapable of performing even the most basic diagnostic tests on not just a car, but their flagship freaking sports car. The fact that their scanner shows nothing is really odd though, especially as the car has a GM calibration in it and not some aftermarket tune. Cars should not ping like this -- bottom line."
We've racked our brains trying to diagnose the problem ourselves. Fuel filter? A clogged filter could cause fuel pressure to drop, making the car run lean... ping. Knock sensor? If the tech's computer showed no recorded knock but we've confirmed audibly that it is in fact there, maybe the sensor is bad.
Our research turned up GM Technical Service Bulletin No. 02-06-04-023A, dated June 2002. Condition: Some customers may comment on a mild to severe engine ping, usually worse during acceleration. Cause: This condition may be the result of corrosion of the rear bank knock sensor due to water intrusion into the sensor cavity. Correction: Replace the rear bank knock sensor and build a dam around the sensor using RTV to divert water away from the sensor.
Corvette owners should be able to go to their dealer for diagnosis and repair of this sort of issue. So we wanted to give ours a shot at fixing the problem. We wanted to give them the the benefit of the doubt. But they let us down. We've done our research. We'd like to find a shop that will do the same. This dealer isn't cutting it. We're headed someplace else.
Mike Schmidt, Vehicle Testing Manager @ 42,430 miles