Omec

iTrader: (2)

i think i need to put it on the dyno to really get a good listen but figured id try asking to see if anyone has any ideas. At high hps (5k+) and really getting on it i get this weird noise from the engine bay. it sounds like the cats are braking up or something if banging around through the exhaust. this noise has been there since i bought the car (3 years ago @ 21k) and played it off as a stock cat failing. since it didnt loose power or make noise any other time other than getting on it i didnt worrie about it. last year i pulled the stock exhaust and installed long tubes and catted y along w/ a m6 swap. the stock cats looked fine btw. i didnt drive it much last year. this year how ever i have and the sound is still there and its kinda loud.

Im not sure what im hearing but its not right. like i said, it doesnt miss a beat and you only hear it when your really giving it the buisness. that and its made this sound since ive owned it so im kinda stumped. when i first got it i noticed the sound right away and though it could be detonation since i had alot of oil in the intake from the pcv system. i installed a catch can and did a tune up w/ new fuel filter. i always run 93 and have tried octain boosters w/ no effect.

any ideas?

Edit - i forgot to mention i did have it dyno'd 2 years ago to check my fuel ratio (when i thought it was spark knock) and stock it did 319hp and 323tq and everything looked good on the graph.

Soul TKR

iTrader: (4)

when I was first reading your description i was thinking "detonation" but since you said you've checked all those other areas, I'm stumped...

got any vacuum leaks going on?

myslow92

iTrader: (4)

I would tend to 2nd that....might get it back and have it checked to see how it's doing

I assume you have gone through everything and checked what you can

Omec

iTrader: (2)

ya as soon as i intitially heard the noise years ago i freaked and though it was detonation because thats really what it sounds like. ive gone over everything short of pulling valve covers ,push rods and such. it wont make the noise w/o a load on it so time to make another trip to the dyno and really listen. i hope its nothing serious.

LS1 Life

I currently have been hearing something similar in my friends ws6 and im guessin its detonation. BUT, talkin with others, theres a possibility of a bad rocker or pushrod.

is the car tuned? lol dumb question i know.

Omec

iTrader: (2)

not a dumb question at all. it just recently got tuned (mail order) one reason why i wanted to get out to the dyno anyways. i have a feeling the a/f will be ok and ive got a mech issue.

LS1 Life

im kinda skidish of those mail orders. Dyno tunes are by far the best. Id look for the broken or damaged rocker or pushrod. if nothin there, you got detonation. A richer mixture is going to be needed... (bigger injectors = big +)

when you do figure it out let me know cuz my buddy is just drivin his car gandma style and not doin anything about the issue.

2000camaroSS2000

no clue thats beyond me

myslow92

iTrader: (4)

ya know now that I think about it a buddy of mines was makin racket also and we figured out it was a bad lifter....its not pushin the push rod up as far as others, and the result is one valve not opening as far as others. and it makes a racket sort of like that.

pull your valve covers, leave coil packs unplugged and have someone crank it over. see if all valve springs are compressing the same amount. If it is like his it will stand out real bad and it does make noise under load only

glad I finally remembered that, I hope it is not that but that I helped in some way

Omec

iTrader: (2)

thanks man for your input. i think you maybe on to something. i do have and have always had lifter noise cold and warm that i think is excessive. i brought it back to the dealer when i first got it and they said it has lifter noise in i think 3 and 5 but goes away when warm. so they wouldnt fix it. looks like i may take it apart to change out to the ls7's sooner than id like. it has to be something like that. ****** it. while its apart -new springs and a cam WOOOOH!

myslow92

iTrader: (4)

so when you tearin it apart to find out??? I am very curious

myslow92

iTrader: (4)

Update????

TopFlite

It possibly could be that your stock belt tensioner is rattling around under load.

98cherrySS

iTrader: (2)

That would be way too easy...

Definitely worth checking though.

Omec

iTrader: (2)

havnt had a chance to do anything yet. im going to try and make an apointment w/ slowhawk and get it on the dyno so he can take a look first before i tear it apart. as soon as i get it over there ill update. im very curious as to what it is. its weird. it doesnt always make the sound whick is kinda screwed up.

topflite - i did replace just the pully a few weeks ago to make sure it wasnt that. the tensioner felt good so i dont think it was that. although it would have been nice lol.