00 Z-28

iTrader: (9)

Have tried cleaning fuel system, changed spark plugs(NGK TR 55)& wires to MSD, changed fuel filter, set back to stock timing, + 5% on PE, still have KR @ 4800 RMP even with it 55 degrees outside(60 degrees IAT & 190 degrees ECT), 890 to 930 reading on O2's, 0 LTFT @ WOT. Any suggestions (besides a rebuild @ 55,000 miles)?

QuickSilver2002

Some ideas

- Decarb procedure (easy and it can help)

- Try disconnecting PCV and putting on some type of breather (blowby gasses going back into the intake can cause KR in the upper RPM range)

- Could be false knock (try race gas and see what happens)

Colonel

The first thing to do is determine if it's real or false KR. Like QuickSilver said, run the tank down low and then toss in some UNLEADED racegas. If you still get the KR then you know it's false. Then you'll need to find out what's causing it. Fun fun!

00 Z-28

iTrader: (9)

Thanks for the reply guy's. I don't think its false, I can hear the audible pinging of the valves, starts at about 4800 RPM's. Jonh @ Diabol Sport sent me 3 custom tunes and on the last one he said he set the timing back to stock. I'm not familiar with timing in the LS1, but when I first start out and give it a little gas the timing shoots up to 41.0 and at high RPM it stays in the 30's. I don't know if that might be the problem.
But, I will try the race gas when my tank get low. Once again, thanks for the reply.