after reaching high rpms and letting off the gas, i get back fires, just wondering if anyone knows why

oh i'm pretty sure my pcv valve is shot and i just haven't replaced it yet, but i doubt that would be related to backfiring

11/5/2006 7:30:21 PM

what kind of car?

because when you close the throttle quickly, the fuel system lags slightly and there is too much fuel in the cylinder for the amount of air that the cylinder gets at closed throttle

it hits the hot exhaust and boom

11/5/2006 7:43:13 PM

isnt this kinda normal

11/5/2006 8:02:41 PM

depends on the car

11/5/2006 8:03:41 PM

also depends on if the exhaust is modified

11/5/2006 8:06:45 PM

that's a feature, not a problem

11/5/2006 8:14:59 PM

sure it's not just a pressure pop

11/5/2006 9:03:21 PM

Doesn't a real back fire come through the intake manifold?

11/5/2006 9:07:52 PM

my truck back fires, my bike back fires, my celica back fires...

11/5/2006 9:14:32 PM

lol

11/5/2006 9:26:13 PM

I wish my car would do it on command. Consider yourself lucky.

11/5/2006 10:22:06 PM

for my cases, the celica had a rusted out exhaust
bike does whenever it feels like it
truck does it if your at 2k and let off the gas

11/5/2006 10:47:37 PM

^^ trust me, it's overrated.

11/5/2006 11:29:12 PM

year/make/model/mods?

could be a number of things, not enough exhaust backpressure, there's an exhaust leak close to manifold, your car runnin rich because of carburation/fuel injection issues, possibly issues with your valves.

11/5/2006 11:38:38 PM

back firing is fun when u wanna feel ghetto. not when ur takin ur boss out to lunch though

[Edited on November 5, 2006 at 11:43 PM. Reason : sadf]

11/5/2006 11:42:43 PM

why does an upstream exhaust leak do this?

11/6/2006 5:32:39 PM

wikipedia can put it better than i can. i always though without the leak the mixture would be too rich to combust in the manifold. but wiki says

Quote :

"When a driver shifts up and lets off the gas, the engine has a moment of running rich or with insufficient oxygen. This causes an incomplete burn which causes the fumes to explode in the exhaust system. The leak itself is the most dangerous aspect. Without it, the mixture would cool enough not to explode."

11/6/2006 6:57:07 PM

a carbureted vehicle with a straight drive will backfire on command. I used to have an old Ford truck that I made backfire all the time. I'd just switch it off while I was going down the road, hit the acclerator a few times to let it load up, and switch it back on. you can crack heads and exhaust manifolds like that, though.

11/6/2006 10:04:02 PM

But how can you put a price on a few cheap laughs?

11/6/2006 10:49:52 PM