Backfire when shifting at WOT?

[IPuOnU]

Well as of late I've noticed that my car backfires when I'm WOT and shift, it's plainly audible, not so much worried about it as I am just curious what could cause it as I am all stock other than exhaust. And that is just second cat and muffler delete. All connections are secure under the hood, and have no leaks. So what else may cause it to Backfire?

[manelscout4life]

Your fp is probably shitting the bed with the cat delete. Buy something to monitor your car... And some real mods

[oh10speed3]

My guess would be fuel pump as well

[IPuOnU]

Meh not to worried about it right now as I said, but good thing I planned on internals and AP when I get back in 4 months.

[manelscout4life]

You might not be worried but keep running your car with a dead fuel pump and you'll need a new engine in no time.

[Tokay444]

Bpv or bov?

[Dre]

lolol @ manel

[JS + MS3]

fp

[Soto]

my car farts too

but i have bolt ons and test pipe

and stage 2 ots map

it sounds beastly

[08.5MS3]

Most likely AFTERFIRE. Backfire is no good.

[silvapain]

It's not the fuel pump; it's the car going rich at throttle lift-off, and the fuel is igniting in the exhaust. It happens to all our cars (ECU runs rich to cool the engine and turbo), but the catalytic convertor absorbs the sound normally.

[Ckmazdaspeed3]

Originally Posted by silvapain It's not the fuel pump; it's the car going rich at throttle lift-off, and the fuel is igniting in the exhaust. It happens to all our cars (ECU runs rich to cool the engine and turbo), but the catalytic convertor absorbs the sound normally.

Wouldn't the car be running rich if the fuel pressure is dropping and the pump is dumping fuel?

[silvapain]

If the pressure drops then less fuel is being pumped in, not more. Plus, it's not at shifting that the pump has pressure issues; it's during WOT in the 4K RPM range (where we get max torque).

[Ckmazdaspeed3]

Idk, I guess I'm missing a piece of the picture, because I am sure that the ecu responds to the pressure drop by dumping fuel... But I will be the first to admit that idk how all the pieces fit together.

[08.5MS3]

Originally Posted by silvapain it's the car going rich at throttle lift-off, and the fuel is igniting in the exhaust.

AKA = Afterfire!

[manelscout4life]

When the pressure drops the ecu adds more fuel.
I was running an atr tuned map with an 11.8 AFR that I matching pretty closely to. When my fp first started breaking down (700-800psi) my AFR would be in the 10's at wot and the car would after fire.

[08.5MS3]

Backfire occurs in the induction side, such as intake valves that do not close soon enough. Afterfire occurs, as stated, with fuel being burned in the exhaust system.

Afterfire is fine. Backfire is not.


Tapawhat?

[aanguia1]

Originally Posted by 08.5MS3 Backfire occurs in the induction side, such as intake valves that do not close soon enough. Afterfire occurs, as stated, with fuel being burned in the exhaust system. Afterfire is fine. Backfire is not. Tapawhat?

Which one is worst? Afterfire or backfire???

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[IPuOnU]

Now that makes sense. and no, stock BPV.

And the reason I'm not worried about it even if it was fuel pump, the farthest my car is moving in the next four months is about 75 feet a couple times a week from the house to the garage. Lol no need to dump money in something that ain't being driven.

But thanks guys I didn't think to look up afterfires, that makes more sense.

[Ckmazdaspeed3]

Originally Posted by manelscout4life When the pressure drops the ecu adds more fuel. I was running an atr tuned map with an 11.8 AFR that I matching pretty closely to. When my fp first started breaking down (700-800psi) my AFR would be in the 10's at wot and the car would after fire.

@silvapain this^^^

Originally Posted by Moore941 Now that makes sense. and no, stock BPV. And the reason I'm not worried about it even if it was fuel pump, the farthest my car is moving in the next four months is about 75 feet a couple times a week from the house to the garage. Lol no need to dump money in something that ain't being driven. But thanks guys I didn't think to look up afterfires, that makes more sense.

While I agree that it is good to know the difference between afterfire and backfire, I still think most of the time on here people call it (though incorrectLy), backfire.

[08.5MS3]

Originally Posted by aanguia1 Which one is worst? Afterfire or backfire??? Sent from my T-Mobile G2 using Tapatalk

Backfire. Your exhaust, your cats, and the heat will burn that shit up.


Tapawhat?

[08.5MS3]

Originally Posted by Ckmazdaspeed3 While I agree that it is good to know the difference between afterfire and backfire, I still think most of the time on here people call it (though incorrectLy), backfire.

Yes. I went through the same thing a few days ago, in relation to OP's problem. I searched and read around. Just for more awareness. I'm kind of a stickler with proper terminology.


Tapawhat?

[Soto]

my car afterfires .

stupid OTS map

my AFR's are like 10.8 at WOT

[mitch11wmm]

My afr was hitting 10s today while on a stock tune and muffler and res delete.
Im getting it tuned soon just knocked out basic stuff first

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[MSMS3]

Holy seven year old dead thread revival! Stock tune will get in the high 10s under max load, WOT at redline. It's deliberate to provide cylinder cooling to control knock. It allows the stock tune to use more aggressive timing than you might think.

By all means get a good tune, but AFR that rich is normal on stock tune up high.

Check your fuel rail pressure to make sure it is 1600 or better under WOT. As these cars age the pump's piston and cylinder wear. If you are getting a tune that raises boost above stock levels, a pump internals upgrade is mandatory, anyway.

And, stop renewing 7 year old threads.

[mitch11wmm]

Lol I didn't even look at the date that's kind of funny.
But yeah I plan on getting hpfp anyways here soon and my fuel pressure is fine. I was just curious about pops

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[silvapain]

Jesus this place has gone downhill with fucking noobs not reading shit.


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