2002 Chevrolet Corvette Z06: Back In Action
March 10, 2010
Is our long-term 2002 Corvette Z06's detonation spell drawing to a close? It appears so.
Bothwell Automotive checked out the MAF sensor and found some damage -- one of the sensing elements was tweaked. Rather than just throw parts at it, Steve Bothwell figured he'd first try to repair the MAF sensor. He did so, and then re-checked the fuel trims. Lo and behold, the fuel trims came down from their previous 14% down to low single digits. The knock had vanished too.
Basically, the tweaked sensor dongas of the MAF made it tell lies. The MAF was reporting to the ECU that less air was entering the engine than in reality. This fib had two very significant side effects -- it made the air/fuel mixture leaner at full whack than it should have been, and the ignition advance more aggressive to boot (sounds kind of like a non-adjustable SAFC...). Just the sort of conditions that are ripe for a ping.
Now, this still doesn't explain why the Z06 apparently can't hear knock, but if the source of the knock is eliminated (as it appears to be), then we're fairly okay with it.
Also, the MAF damage was caused by a thing, and that thing may have kicked the snot out of the MAF on its way into the engine. Seems unlikely. Our Z06 feels quite strong, and such a snot-kicking thing would cause it not to be so. The damage was more likely done by mishandling. Perhaps the previous owner's mechanic was some kind of ape.
I'll be giving the Z06 a good rogering today to fully convince myself of its knock-free-ness, just to be 100% certain. You know, in the interests of science.
Jason Kavanagh, Engineering Editor