SladeX

Diagnosing knock

Here we have a stock 05 vette. It has KR from 3-7 @ WOT and random KR under load in any gear (although sporadic and 1-2 at most)

55k miles
Did plugs and wires TR6 (tried TR5, Granatelli wires, MSD wires, stock)
Fresh oil change
Coolant level fine (may do flush)
Engine temps average 210F
IAT around 90-100F (hit 130, discounted that log, but multiple logging with sane temps too)
Suspecting knock is false
Tried reducing timing (its stock 23 @ WOT, but dropping to 17 did nothing)
Seafoamed engine, no change
Tried desensitizing sensors (went from 4-5 stock average to as high as 11 for each cylinder, suspect somthing is "hitting")
I'm not hearing anything inside which could be triggering the knock
I'm back at stock settings again and stumped to what the sensors are hearing.... is it real or is it fake? May bite bullet and take to shop...

redtan

iTrader: (5)

If you lowered timing by 6 and still get the same KR then it's surely fake and something must be causing this audible noise in the engine bay.

SladeX

I'm debating its fakeness now. After seafoam #2, the cruise KR cleaned up very nicely. The WOT KR is still around but the engine was showing 0's for the first time with 17 degrees of timing. I will restore the stock table and see where knock learn finalizes itself. I noticed even in WOT, KL still works its magic so I can use that to guage what the final timing to run is.

I still think I should do at least 1 more seafoam to it followed by an oil change.

SladeX

I'm also ready to admit that maybe the LS2 needs just wants less timing even if it is stock. It's making me think that GM did this super rich tune + KL even in WOT in order to apply a generic 1 tune fits all to all its engines despite that there will be variations of engines in build and uniqueness to each engine.

redtan

iTrader: (5)

Never seen that. My stock internal LS2 took up to 26-28* of timing even with lean AFRs in the upper 12s. Made best power at richer AFRs around 12.4-12.6 but it definitely liked timing and certainly more than stock.

SladeX

I've done a lot of reading and getting mixed results on the stock LS2 cars. As stated 1 may like more timing, and another may like less. My LS3 cammed transplant in the Camaro is begging to be richer with more timing on the same fuel.

Another seafoam will be done in the next day or so followed by a start low, move up kind of deal. I've left the knock sensors to the same sensitivity in order to protect me from knock, but eased up on knock attack to make sure that the knock it hears is genuine. I'm running 91 Shell octane here for mileage purposes since everything else has 10% ethanol. I think I may have found a source for 93 octane with no ethanol so I will check that out but looks like to be safe 91 tune is better for long trips and availability.

I've also found the MAF tables to be dialed in very similarly to my 85mm maf installed on the Camaro, after logging SD and MAf, I think its pretty much dialed in. LTFT seems to agree with -1 -2 across the board during cruise when both MAF and MAP running stock. I think I'll have the WOT dialed in by the weekend and I will just enjoy the Vette for being a vette. The Camaro is the toy with the power and $$ invested in it.