What causes detonation only with A/C on at partial throttle

[Redfox0099]

So yeah.... I run 93 Octane gasoline with a Diablo and a B&G tune on it (No CMR done to it....can't find anyone to tune my car) and with the A/C on under partial throttle I get a little rattle out of the motor...only at certain places in the petal and my bottom end is forged so it can take a little punishment....


Any ideas??? WOT my A/F is 12.1

[CoolVanilla]

Red, do you have a Predator yet? Do some logging brutha, and send me the file. Be interested to see if anything becomes obvious.

[Redfox0099]

...as posted in Post #1 I have a Diablo yes...if you weren't so busy banning people you might of seen that (and take off those silly sunglasses Cartman....no one thinks you are a cop).

[CoolVanilla]

...as posted in Post #1 I have a Diablo yes...if you weren't so busy banning people you might of seen that (and take off those silly sunglasses Cartman....no one thinks you are a cop).

Geebus you have an odd way of asking for help. Didn't know if *you* had the Pred, or if it was at one of the hundreds of other places your car has been at lately... feel me, asshat?

Well log 1/1 and 2/1 Long term ADAP for a while, making sure to do so during the problem. Let me know when you've got that file and maybe I can take a look. No promises anything will come of it though... I'm no expert thats fur sure.

[PowerWagon896]

So yeah.... I run 93 Octane gasoline with a Diablo and a B&G tune on it (No CMR done to it....can't find anyone to tune my car) and with the A/C on under partial throttle I get a little rattle out of the motor...only at certain places in the petal and my bottom end is forged so it can take a little punishment....


Any ideas??? WOT my A/F is 12.1

Several people have broken ring lands due to detonation W/that tune on "highly modified" engines.

It is not advisable when heads & cam have been changed.

[Super T]

Dude, if you don't have an actual tune on your car, stop running it hard... RIGHT NOW.

[Redfox0099]

Dude, if you don't have an actual tune on your car, stop running it hard... RIGHT NOW.

It has been doing it for over a year, it is barely audible.

[CoolVanilla]

Red, log Actual Spark Cyl 1 too...

[Super T]

It has been doing it for over a year, it is barely audible.

Then maybe it's not detonation at all... but seriously, many an engine has blown from improper tuning... I may be overreacting because I don't know all the details, but from the way it sounded just now you're running something canned w/ that monster of a stroker you have... if so, and I were you, I'd stop pushing my luck after a year of ass-whompin on the engine and go find some real, real cheap insurance in the form of a tune! If you got a custom flash from Dave or something, then I'm ramblin for nothing because you're probably fine.

[Redfox0099]

It is a Stroker tune by Dave....like I said the only time it makes any noise is with the A/C on at partial throttle, 35-55 mph, 2000-2500 RPM but not under WOT.

[Super T]

But not at other speeds but same RPM (like in a different gear, same RPM)??? I guess it's possible that the maps are a little lean in that range. Is it possible that the AC clutch is just getting chattery from all the floggings??

[Redfox0099]

Do some logging brutha, and send me the file.

Sent you a file from a little while back, I will log some this weekend and send it to you.

[CoolVanilla]

Sent you a file from a little while back, I will log some this weekend and send it to you.

Got it Nathan. Unfortunately it doesn't contain the 1/1 Long Term ADAP, 2/1 Long Term ADAP or Actual Spark Cyl 1 data. Make sure you add this in to your logging this weekend. Its those values that are of particular interest...

[Sharadon]

Audibal detonation is like a hammer hitting the piston. Forged pistons can take it for a long time. But still isn't good for them. It will also kill the bearings. Stop it please.

[fnkychkn]

this guy thought he had a spark knock and it ended up being the EGR resonating through his CAI.