detonation?

[MoKo_03SVT]

okay, so heres the deal. recently i swapped my upper pulley down to a 2.8. the install went fine, and all that, but i have noticed a new sound when at WOT. im not sure what the sound is, but i know what i hope the sound ISNT, and thats detonation.

ive done some searches on here, and what seems to be real common, is people describing the sound of detonation as rocks/marbles rolling around in a tin can. well....this is basically what it sounds like. the car runs fine, and pulls super hard with no hesitation, but i keep hearing this sound. the strange thing is, it is almost sounding like its coming from the shifter area, and not really the engine. the sound isnt super loud or anything, but i do hear it.

i guess my questions are: when you hear detonation, is it usually pretty loud? when it does happen, can you tell for sure that the sound is coming from the engine, and not anywhere else? i know with the extra power (when it all kicks in) there seems to be a few new rattles in the interior, so maybe im just being paranoid, and this is just a new rattle/noise?

i took my diablo predator and went into my tune and made it 1% richer and took off a little timing, to see if this would make the noise stop, but it still does it.

mods are: 2.8 upper, JLT RAI, Steeda cat-back, Diablosport predator (w/ canned tunes)

any help, suggestions, descriptions of detonation, etc. are greatly appreciated.

 

[TT04Cobra]

Did you retune after putting on the pulley or did you just throw the pulley on and go make WOT pulls?

 

[MoKo_03SVT]

i put the "pulley performance tune" on, after swapping the pulley, before starting the car.

the tune is just a canned tune though. the same canned pulley tune that comes on all diablo predators

 

[RoadRash]

You better get tuned and check a/f pronto. The cost of a new motor is $$$ .. ask me how I know.

 

[MoKo_03SVT]

so when detonation occurs though, is it usually pretty loud, and easy to notice? when it does happen, can you tell for sure that its coming from the engine? its weird, this sounds like its coming from the shifter/tranny area....i dont know.

edit: i do agree though, that i need better than a canned tune, and DO plan on getting that done. this canned tune was/is supposed to get me by until i can take the 3-4 hour trip down to dallas to get tuned.

 

[RoadRash]

Do yourself a favor and get that thing on a dyno and verify the a/f ratio. It is worth the $75 to do that locally. I was running a "temp" tune and didn't get mine checked and before I could get to the tuner, I blew my motor .. no sounds of detonation either.

 

[MoKo_03SVT]

right...i know i need to do that as soon as i can, for sure.

i guess what im hoping for is someone to come on here saying something like "dont worry about it, you'd know if it was detonation because it would be super loud"...or "you'd know cause there is no other sound like it" ...something like that...but...thats not happening haha =/

 

[Fat-cat]

Detonation is not super loud. Infact with how loud the blower whine is you would be lucky to hear it at all. You could be hearing detonation as it can resonate in the exhaust and could be heard in the trans tunnel.. Dont go WOT again until you have the tune checked. If it just started after the pulley install i would bet the tune is out.

 

[MoKo_03SVT]

something i thought of earlier, but havent done, or ran by anyone is...do you think i should put a gallon or so of 100 octane to be safe?

 

[HURTNEM]

Do you hear the rattle/tin can noise when you rev the engine or only when you're WOT? Reason I ask is a blown CAT makes the same noise you desrcibe above. This could also exlain why you feel the noise is coming from your shifter area as your CATS are right under your shifter area. Seems simple, but may be something as simple as that. I've replaced blown CATS twice and they made the sound you decribed.

 

[MoKo_03SVT]

well...i do still have the stock mid-pipe, so i guess that always could be a possibility.

im not sure if it makes the noise when i rev or not, i'll have to check. also it seems like i can hear the noise w/out goin all the way WOT...if i give it just enough gas to kick in full boost from a fairly low RPM (in any gear), on the initial jolt (when it all kicks in) is when i hear it. it doesnt make the noise the whole time i have it in boost. this is included when going WOT...doesnt make the noise the whole time.

 

[trmin8ter03]

Check your pump for the heat exchanger. Make sure the water in the tank is moving around. That was my problem. If your air intake temp is too high the computer will mess with the timing and cause detonation.

 

[1wild-horse]

Ping!

 

[HISSMAN]

I preach the following : A canned tune should only be used for purposes of getting your car to a reliable tuner or purchase a mail order tune from a reliable tuner.

-Jeff

 

[HISSMAN]

Ping!

What is ping for?

 

[1wild-horse]

thats the sound us old dogs use to describe detonation, it pings! you never heard that b4?

 

[HISSMAN]

thats the sound us old dogs use to describe detonation, it pings! you never heard that b4?

yeah, just thought maybe you were using that to subscribe, or up ye olde post count ;-)

 

[MoKo_03SVT]

Check your pump for the heat exchanger. Make sure the water in the tank is moving around. That was my problem. If your air intake temp is too high the computer will mess with the timing and cause detonation.

excellent, thank you. i will check this as soon as i get off of work.

 

[1wild-horse]

just my thoughts on the problem... definately deto. canned tune from diablo is wrong, speaking from personal experience. i even reloaded the stock tune and stayed out of the boost to drive it to the tuner b/c i could stay in the throttle longer without it "PINGING" get a custom tune and you'll be o.k. OH and make sure you drive it afterwards to see if it pings going down the road as the road is not as forgiving as the rollers on the dyno. I had to take a couple degrees of timing out of mine. Just wanted it safe.

 

[MoKo_03SVT]

just my thoughts on the problem... definately deto. canned tune from diablo is wrong, speaking from personal experience. i even reloaded the stock tune and stayed out of the boost to drive it to the tuner b/c i could stay in the throttle longer without it "PINGING" get a custom tune and you'll be o.k. OH and make sure you drive it afterwards to see if it pings going down the road as the road is not as forgiving as the rollers on the dyno. I had to take a couple degrees of timing out of mine. Just wanted it safe.

i was thinking of maybe adding a gallon or so of 100 octane to see if that helps. if it does make the noise go away, then it would for sure be detonation....right? but if the noise is still there...then maybe its not detonation?