I'm trying to track down some high RPM detonation. It only happens when the car is up to temp. It has been suggested that w/ my intake and exhaust improvments, that I may have a lean mixture, which I can accept, but is detonation under lean conditions predicated on a hot engine? When it's still coming up at about, say 160, it runs great, no detonation.

I'm trying to determine if it's a lean condition I can fix w/ a MAF translator, or is it running too hot, in which case I can drop in a lower stat, and cooler plugs maybe.

HELP

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2001 Formula
307RWHP/331RWTQ

Direct-Flo w/ Holley
!MAF screen
FRA
Flowmaster
Kirban Kwik Six
SLP STB and SFC's

 

Well to be technical I beleive you mean retard, you are getting retard at the higher rpms. You shouldn't ever be getting detonation that's what the computer prevents. If you were actually getting detonation you would be damaging internal components.
How do you know your getting retard...? Auto tap? Higher octane is a common quik fix, 93 minimum no 92 or less.

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99 SS, Dark Metallic Blue, M6
SLP lid, KN, TBB, SLP Y-pipe, SLP loudmouth
ported MAFs, Nitto 315 DRs
Currently: 1/4 13.06@113.8 (gtech runs high in mph by about 4mph), 0-60 4.77 (w/passenger) Gtech'd
12.99@110.2, 2.06 60ft - Tazzo.
Also, 331 rwhp as measured on the Gtech

 

you cant get KR unless you get detonation. the computer isnt psychic, it doesnt predict detonation, it corrects after you get it, and if you get enough it may switch timing tables to the lower octane table to try to save the motor, but that reverts back to the standard high octane one after you add fuel. people get detonation all the time, and it doenst always damage the motor.

Yes heat can make a lean knock show up, If I had to guess by looking at your mods, i'd say descreening the MAF might have done it, some cars have trouble with that, particularly the later cars..

 

Freak is on to something. Your PCM Should correct a lean condition, if it knows about it. Normally, the PCM would pick up the increase in airflow and adjust mixture accordingly. Without the airscreen, the air is not hitting the MAF at the right angle to give a correct reading. The difference is so slight that it only shows up at higher temps. More airflow that the computer knows about=lean mixture. Good luck and be sure to post the fix.

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2000 Camaro Z28 Monterey Maroon Metallic, auto,leather, 323 posi, Monsoon w/CD, T-tops, K&N

 

To clarify, yes the knock sensor is retarding the timing. The pinging can be heard, and it showed up distinctly on the dyno chart. It was a nice smooth curve up to 4200, then there was a noticable increase in the raggedness of the curve, and the curve leveled off somewhat, though it continued upwards, and peaked where you would expect it to (a continuation of the original curves look like they would have given me 10 more hp/tq before the knock sensor kicked in). I have never used less than 92 octane, and the fuel system has been cleaned so I've done everything I can do to clear up any carbon deposits.

Best I can recall, I de-screened the MAF AFTER the dyno run, so it was happening before that. And I also assumed that the PCM would measure the increased airflow and adjust the mixture accordingly. The guys at AMS seemed fairly certain that the factory plugs are just too hot, and that I needed cooler ones.

Keep in mind that when the car is warm, but not fully up to temp, there is no pinging at all. It pulls beautifully all the way to redline, so I'm not so sure it's a MAF problem. I just don't know. Has anyone had this problem and solved it w/ a cooler plug?

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2001 Formula
307RWHP/331RWTQ

Direct-Flo w/ Holley
!MAF screen
FRA
Flowmaster
Kirban Kwik Six
SLP STB and SFC's