I installed a fsport exhaust on my IS350 a few months ago and it was great at first. Recently, however, I have noticed that when I slow down for a red light (and the car downshifts), the exhaust makes a weird popping sound. Is this considered backfiring? All I have on my car is a fsport exhaust/intake setup...no mid pipes...

Has anyone else with a fsport exhaust noticed this?

 

I get a little 'pop' noise, usually when I'm coming to a stop say, at a traffic light.

 

hmmm i have the same setup as you but haven't ever noticed anything like that :\

 

i have it too :S is it bad?

 

the pop you hear is just unburnt fuel going through your exhaust piping. Its really nothing at all. You could just be running a tad bit rich but nothing bad....

 

Any idea as to why it's heard with an aftermarket exhaust and not with the stock exhaust?

 

so does your car waste more gas like that? and doesn't your exhaust tip turn black after a while of backfiring?

 

Don't the exhaust tips turn black even on the stock ones?

I have not heard this happens to mine, but will keep a close ear on it.

 

Backfiring doesnt necessary mean burning more gas, unless you have a midpipe. After installing my midpipe i saw the difference in gas mileage. OUCH!

 

the engine burns gas, not the midpipe.

as aftermarket midpipes are relatively less restrictive, this translates into a higher rate at which exhaust fumes leave the engine, causing an slight increase in horsepower and decrease in fuel economy.

maybe someone who got an "A" in fluid dynamics 101 can give a better, more thorough explanation...

as for the popping noise... it should not be "backfire", since modern engines and emissions systems are sophisticated enough to prevent that from happening.

 

^^Well i didnt feel like editing what i said. But thanks for explaining bro. lolz