07 STi Backfiring
 

Hi Guys,

Kinda new to the forum and have recently purchased my very first wrexy it's an 07 WRX Sti. It came with some nice mods; turbo back, walbro fuel pump and BOV, the car had also been tuned to around 260whp which from what i have read is safe. I really like the car and the way it sounds, however hearing the engine backfire doesn't sound good and in my eyes can't be in anyway good for the engine. I was told that it's backfiring due to the fuel pump drinking more than it should and the bang is excess fuel that hasn't been used. Just hoping someone can shed some light on the matter, is it worth having it tuned again or?

Also not too concerned on stopping this if it's not going to destroy the car.

Cheers

Is that just when you lift off? It could be the BOV. I would change it to a plumb back. having some backfire on lift off is normal with the exhaust. Just running a bit rich which is on the safe side. Fuel pump will not cause you to put more fuel in the engine. Any excess fuel will be returned to the tank.

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I'm sorry, i cant answer your question though I'm curious of this too.

My car does it quite frequently, everyone told me that its OK "its a WRX thing" or something. :) took my car down to the drags and both times I've hit limiter and backfired but this time a big flame came out the exhaust. everyone said that was fine too...

im not sure of the technical side of it but in my car apparently soemthing has been swapped and that it send the same amount of fuel through, and thats why. But i'm not good at this stuff.

So in all my jabble i'm looking for a more mechanical reason

I'm not expert so please correct if i'm wrong,

Its probably the atmospheric BOV thats causing the backfiring (It's not an issue)

I believe it caused by an excess of fuel in the system, this occurs when the BOV releases air into the atmosphere it causes a temporary unbalance in the air/fuel ratio being combusted. With it being slightly richer thats when you'll find it popping and backfiring.

I have an 05 Sti with indentical mods, and its occured once or twice when i missed a gear whilst reving it out hard.

Having an 'atmospherioc BOV' will increase your fuel consumption slightly due to these unbalanced ratio's. Alot of people would suggest switching it back to the standard plumb back model (which i would if i could click my fingers and have it changed). The only beneficial/reasons why people put them as far as im aware is

1) They like the sound it makes
2) Slightly improved throttle response (i think due to temporary richness after shift)
3) I've read the standard ones CAN start to leak around 22ish psi?

From my understanding it isnt necessary at all unless chasing big power. and i would remove it next time you were getting you car tuned.

Again this is all information i've read online (unfortunately a lot of online information is opinion and wrong) so if im off target with anything here some one correct me.

Backfiring is normal for most WRX's with an exhaust and bolt on modifications..

Usually on downshift and feathering the throttle will cause this.

If the car is doing it excessivley and running very rich, it would be worth getting the AFR checked and possibly retuned.

Emjay, does your car have antilag enabled? That would be the cause of the flames...

:) I dont even know what that means! hahahhaa!!! how would I find that out??

[QUOTE=Brett Allan;758223]Backfiring is normal for most WRX's with an exhaust and bolt on modifications..

Usually on downshift and feathering the throttle will cause this.

If the car is doing it excessivley and running very rich, it would be worth getting the AFR checked and possibly retuned.

Emjay, does your car have antilag enabled? That would be the cause of the flames...[/QUOTE]

it only backfires when slowing down and it's just literally one loud bang, a few seconds after getting off the gas. The BOV is a turbosmart. Thanks for the info.

No her car does not have antilag.

no catalytic convertor either by the sound of it (flames)

[QUOTE=Emjay;758217]I'm sorry, i cant answer your question though I'm curious of this too.

My car does it quite frequently, everyone told me that its OK "its a WRX thing" or something. :) took my car down to the drags and both times I've hit limiter and backfired but this time a big flame came out the exhaust. everyone said that was fine too...

im not sure of the technical side of it but in my car apparently soemthing has been swapped and that it send the same amount of fuel through, and thats why. But i'm not good at this stuff.

So in all my jabble i'm looking for a more mechanical reason[/QUOTE]


Install small bbq near exhaust and wait for car backfire flame... mmmmmm dinner cooked... no more kitchen :D