Ok so when im driving or on the throttle everything is good, then when i let off to shift gears, coast in gear or downshift to slow down i get a "popping" noise. sometimes real light and sometimes a little louder. Am i backfiring? What causes the car to backfire?? what can i do to fix this problem?? thanks

 

My car does it but its because I have a gutted cat, do you have the stock cat on there ? Sometimes a leaking exhaust valve will cause a sound like this, but it would not just be when you let off the gas.

 

Do you have an aftermarket exhaust? Lack of back pressure will make it back fire.

 

my car does the same thing, it s because of the blown muffler i have on it though and i think the the cat brick is blowing out of teh piping also...

 

I have an open canister exhaust. when i had my d15b2 i had no noise, after the swap im gettin the noise, and the exhaust is alot louder too. maybe leaking exhaust??? or no back pressure?? I'll hafta check it out. thanks for the help

 

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Ok so when im driving or on the throttle everything is good, then when i let off to shift gears, coast in gear or downshift to slow down
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Downshifting to slow down is a bad thing, you continue to do that you will wear out the tranny, believe me it happened to me and they arn't cheap to get rebuilt.

On the subject Mine does this only sometimes, I think it's becuase of the piping.

 

i have the same problem with my integra.Slowing down tends too back fire.I might replace the muffler with a better flowing one.Not sure what else it could be?

 

I'm assuming it's something in the exhaust, either the cat or muffler cuz I am on my second a6 right now and they both did it.

 

it's due to an excess of unburned fuel igniting inside your exhaust, not nesicarly a bad thing. But it means your catalatic is not working at a sufficuent rate. With an aftermarket exhaust this tends to happen. Especially with a motor that consumes more fuel than your system is built for. when the throttle is closed you are not allowing fresh air into the head to burn the idle fuel, and since your motor is still at a higher RPM it is pushing exhaust gasses out at a higher rate. so when it meets the fresh air near the tip of your exhaust (or in wich point you have a leak) it ignites causing a pooping sound or "backfire".

 

ahh knowledge is power. thanks