Okay.. this almost NEVER happens during light throttle.. but sometimes when I go WOT I hear a pop or two... I don't think that it's detonation because I thought that that would be constant... this only happens like once every 2-3 seconds. It also sometimes happens as I'm letting off the throttle, during a shift or something.

 

wot? at high rpms mostly? your hearing some backfire you're probably running a little rich

 

Yeah, it's definatly a backfire, especially if it's always after you left off the throttle/hold the throttle constant. As was mentioned, you're running rich, and it's causing it to combust in the exhaust, Mine does the same thing, although I can get it only going up to about 4500 RPM (that's as high as I've had the car on this rebuild). From what i've heard (never done it), Detonation, when it sounds like popping, it's more like popcorn, a "hollow" popping sound.. Mine is a definitive gasoline combustion pop.. I know i'm running rich, after the breakin is complete, i'm probably going to run a Safc II or something to let me lean it out a bit...

 

backfire happens when you're running rich. This would be my initial guess. I think you'll know what pining/detonation sounds like when you hear it...

 

yeah i noticed mine does this too when i got my cat back system. i heard it was a rotary thing and is more audible when you free up the exhaust system.
btw i like that "popcorn", great way of describing it

 

I now think that it is detonation... it sounds like the "hollow popping noise"....

 

try running a grade higher octane on the next fillup...be nice to her until then...

 

yep! that did the trick.. went from 87 to 89 and goodbye ping... looks like it was time to move up

 

What boost are you running at? I thought you were nearly stock?

 

Snrub: I was nearly stock.


and the car ran fine on 87.

then I installed a full exhaust and an intake.

And now 87 is simply not quite good enough. sometimes it'll ping, sometimes it won't. 89 however, seems to work just fine now. which is good, because premium is friggin expensive.