I have a 89 camaro rs and it has a 355 moter in it. when i let off the gas the car starts to back fire and when i take off the car dont seem to have any power till i hit 3500 rpms

 

You might want to check your valve lash. My valves were out of whack and it ran like a dog until the revs came up. Of course I'd check the easy stuff first, like your timing, pick-up coil,and ignition module.

 

Definitely look at timing. May be retarded too much

 

So its normal or not for our car to backfire wen ltting of the throttle?

Only happends wen doing more than 3000rpm and letting of quickly.

Thanks.

(I really dont know if it has any loss power bellow 3000) anyone had a power curve from a stock LO3? It fell much stronger at 2500 than below that but is pretty quick anyway)

 

If you have all your exhaust components (cat/muffler) properly installed on a relatively stock engine it should never backfire.

 

WAIT A MINUTE!!

Are we talking about big bang backfire... or the more soothing popping sound that a free flowing exhaust will inspire?

 

Well The engine is stock but I have no cat, and the muffler is still the original (aprox. 70.000 miles)

Only on two ocations I heard a loud pop under full aceleration at 4k plus rpms (less than 4.5k) but i think that was detonation not backfire.

 

leaking headers will couse a backfire

 

Are we talking about backfire or afterfire? When you go full throttle about 2000rpm, does it bog then pick back up a little later? Can you give me more info on your setup?

Jerry

 

do u have ur air pump hooked up to the cat? or is the little pipe just open? if the pipe is open thats ur problem.

 

So if my headers dont have the AIR tubes pluged but Im not using them, it could be causing a backfire (not the exhaust popping when you let off the gas) to happen at low rpms?

 

that doesnt matter too much...what matters is if there is any air going to the converter. if the air line is not hooked up to the converter it iwll make that poppong noise