backfires?

[NiteRider]

what causes cars to backfire?
i was drivn my buddies 240w/sr20det, and i made it backfire, and no one has made the car do that before.
and then i test drove a neon srt-4 and i also made it backfire, i dont get it.
what causes this to happen

[sxtasy]

unburnt fuel being ignited

[NiteRider]

even in stock cars?

[shadow]

Ok please feel free to correct me if I am wrong.. but backfiring occurs when not all of the gas is burned off in the combustion cycle. When not all of the fuel is burned it enters the exhaust system every once in a while usually during deceleration or when shifting a gear there is too much gas. When some gas gets into the exhaust system it is possible that it will ignite in the exhaust creating small explosions which can be heard as the popping sound. It also tends to happen if you are running a little rich... which is not as bad though as running lean. I get backfires and flames a fair bit with my rx-7.

Anyone have some more input.. hopefully I got it mostly right.

Under the right conditions stock cars can backfire.. because they are usually programmed to run at safer levels of air to fuel ratio which tends to be rich.

[NiteRider]

ive never had this happen to me before, ive had cars before, and they havnt backfired

[shadow]

It can happen haha :)

[NiteRider]

SHIT SON

[dj_rice]

I read on SCC that when a car backfires after letting up on the throttle its cuz its running a lil rich?Is that the same as the unburnt fuel theory?

[dj_rice]

Okay nevermind..I didnt read all of shadows post lol ignore what I said :dunno:

[dj_rice]

Okay nevermind..I didnt read all of shadows post lol ignore what I said :dunno:

[shadow]

usually you will never see flames though unless you do not have a catalytic convertor because the explosion will occur infront of it and .... er should.. not make it through. Explosions in your exhaust is not that great of a thing anyways.. it is just harder on your parts. The only place explosions should happen is in the engine. If you do not have cats tho and you are running high octane fuel and are a little rich, then afterburn or backfires are quite common. If it continues to happen regularily it might not be too good... cause I am not sure what it will do to your catalytic convertor.

[Idratherbsidewayz]

Well it happened on my car. No clue how he did it. Been driving it since last summer, and he took if for a ride once and backfired it. I don't have a cat, full 3" turbo back exhaust. Im not running rich because my car's emanage has been tuned. Who knows, fluke backfire...

[NiteRider]

Originally posted by Idratherbsidewayz
Well it happened on my car. No clue how he did it. Been driving it since last summer, and he took if for a ride once and backfired it. I don't have a cat, full 3" turbo back exhaust. Im not running rich because my car's emanage has been tuned. Who knows, fluke backfire...
u almost shit your pants

[xDiMSuMx]

isn't this afterfire? not backfire?

[shadow]

I always understood it as... backfire is the ignition of the fuel in the exhaust... afterfire or afterburn is the proceeding visual burn which can be seen. You can backfire without afterfire or afterburn it just means it is contained within the exhaust system.. That is just how I remember it... but I am no conclusive expert on the terminology of backfiring... =P

[GT2NV]

Originally posted by NiteRider
SHIT SON :rofl: :rofl: :thumbsup:

[ehrgeiz]

Gotta love the RX-7's 6 o'clock gunshot

[atomic]

Originally posted by Idratherbsidewayz
Well it happened on my car. No clue how he did it. Been driving it since last summer, and he took if for a ride once and backfired it. I don't have a cat, full 3" turbo back exhaust. Im not running rich because my car's emanage has been tuned. Who knows, fluke backfire...

you don't have a cat which helps back fire .

but you are running rich when u let off throttle . which is why it's back firing . when you let off throttle, there butterfly closes and no more air is getting to the motor, the last bit of fuel injected doesn't have any air to fully burn it . so the fuel leaves your block mixed with a bit of exhaust . when it gets in the header the heat and the bit of air from scavenging ignites the fuel . and POP

[Idratherbsidewayz]

Originally posted by atomic


you don't have a cat which helps back fire .

but you are running rich when u let off throttle . which is why it's back firing . when you let off throttle, there butterfly closes and no more air is getting to the motor, the last bit of fuel injected doesn't have any air to fully burn it . so the fuel leaves your block mixed with a bit of exhaust . when it gets in the header the heat and the bit of air from scavenging ignites the fuel . and POP

That makes sense. Whenever I drive it I let off the gas slowly, but Todd wasn't used to driving my car so he mustve let it off super quick resulting in the backfire...