So after removing the resonator, the car backfires a little when I let the engine rev down from higher rpms. Is this bad on anything? What will I damage by letting it do this, and how long do you think I can go before the damage occurs? I like the sound I get when I let the engine rev down (from about 3K-3500K) but I don't want to jack anything up. Someone told me I could burn a valve or mess up a piston. I don't know, so I'm turning to my Scion family for some thoughts on it.

 

moved to better location for more possible feedback.

From what I've heard it is bad on the pistons and the rods for a backfire which is trying to force the piston in an opposite direction or something.......im not a mechanic though so don't quote me.

 

From the sound of what ur describing that's more of a popping affect from the exhaust having a low backpressure. Believe me u'll know a real backfire when u hear it and that's not it.

 

yea, it does sound more like a poping, and I know it's due to lack of back pressure. Does the popping or lack of back pressure hurt anything?

 

no it doesn't hurt anything heck i can even hear my car popping when i get off the gas and all i got is a dc 4-1 header and the trd muffler

 

[quote="MTcX"... From what I've heard it is bad on the pistons and the rods for a backfire which is trying to force the piston in an opposite direction or something.......im not a mechanic though so don't quote me.[/quote]I think you are referring the situation where the mixture in the combustion chamber ignites so far before the top of the piston stroke that the piston is forced down before it can reach the top. This is better called a misfire, or pre-ignition, is caused by the timing being advanced too far. You can experience it when kick-starting an old motorcycle, in which case the lever will kick back hard. Or you can experience it in any engine when running, as knocking or pinging.
A backfire, on the other hand, is caused by ignition of the mixture outside the combustion chamber. There can be backfires in carburetors when starting, and more likely backfires in the exhaust system from unburned gases.
But you are referring to a continuous soft popping sound in the exhaust on deceleration, not a single loud backfire. The popping sound is common in exhaust systems with low backpressure. If you remove more of the exhaust restriction, the sound will become a loud crackle.

 

Ok, currently I'm running without a resonator, but I still have the stock muffler, if I swap the stock muffler out with something larger, will the crackle be louder\more frequent, and will I have an issue with backpressure? is it bad to not have enough back pressure?

 

its fine, my green one does the same thing.

 

Don't you need backpressure for torque?

 

The resonator does muffle up sounds from the engine so removing it will make the car sound alot louder. Backfire will sound like gunshots.

 

You will not hurt your car. n/a cars require little back pressure to function at an optimal level. Most of the time a header and plain straight pipe back to the rear of your car will create suffiecent backpressure. You will get used to the sound

 

go to your nearest exhaust shop and ask them to set you up with a muffler that will eliminate the backfire, and help your pipes breath better.

 

I guess it's been established that it is not backfiring.

 

Way to bring back a dead thread from 2-1/2 years ago.