Backfiring...

[twcblackhand6970]

My car backfires loud when I get up to about 70 on heavy accel. then close throttle and then as I'm slowing down I can hear little ones. Also when I'm coasting on highway and give it some gas to accelerate a little, right when I press the gas I can hear some backfiring, but just for a second and it's only like 2 or 3 little ones. Any "usual suspects"?:secret:

[HoLLo]

Mine does that.. I thought that a tune would help. it did a little but I occasionally still get it. I hear a lot of LT1s do it.. I think its just what a stock motor does with free-flowing exhaust period. ?

[Z28pr0jekt]

most likely

"ORY to straight pipe"

[Brian2006]

Is it an actual misfire? I.E. does your SES light flash? If so, then your problem is somewhere in the ignition. Check your plugs, wires, and coil packs.

If it's just backfiring, then you probably have an exhaust leak

[twcblackhand6970]

my ses light is on, but it's emissions stuff my mechanic said, like egr valve bad and some others.

[fuels94]

I agree with Brain2006 most likely you have an exhaust leak when your driving around.

But it if it's doing it at idle then you have a bad injector.

[twcblackhand6970]

I do have an exhaust leak at the y-pipe to i-pipe flange.

[jarretthise]

just throwing this out there but...is your firing order right?? exhaust leak!! is it doing it constantly at an idle

[twcblackhand6970]

I don't think my firing order out of order. And no, at idle it doesn't do it, only on decel. and when I press the gas coming off a coast on the highway. And my throttle response is about 1sec delay if that helps.

[Fixxer99TA]

When your coasting down on the highway and get back on it, that little backfire or pop is normal.. LT1s do it and I think I even remember my LS1 doing it with the LTs/ORY.

When you have the stock manifolds on there and cats with a good exhaust, you just cant hear it... Which is exactly what GM needed to do to sell them to everyone and not just people who mod them. But as soon as you start putting performance exhaust, headers, taking away the cats ect. you start hearing it breathe and pop :D

I have no idea what you mean by "it backfires on heavy accel at 70, just 70 and nowhere else? Are we talking a little pop or a full on BANG like a backfire?

[enjoi355]

...then close throttle and then as I'm slowing down I can hear little ones. Also when I'm coasting on highway and give it some gas to accelerate a little, right when I press the gas I can hear some backfiring, but just for a second and it's only like 2 or 3 little ones. Any "usual suspects"?:secret:

so this is nornal?? mine has always done this and ive always wondered about it

[twcblackhand6970]

By full on popping at 70 I mean, I accelerate as fast as possible (WOT) and let off gas at about 70-80 and while it's coming off the RPMs I sometimes hear a full, extremely loud backfire, like a gunshot.

[enjoi355]

X2 , do you let off the throttle super fast?? or run it hard then just let off?? cause thats when mine does it also... but its wierd cause its always been like that

[twcblackhand6970]

from WOT then let off all the way quick. just pop off the throttle

[enjoi355]

yeah thats when mine does it too, does anyone know anything about this??

[Fixxer99TA]

When your coasting down on the highway and get back on it, that little backfire or pop is normal.. LT1s do it and I think I even remember my LS1 doing it with the LTs/ORY.

When you have the stock manifolds on there and cats with a good exhaust, you just cant hear it... Which is exactly what GM needed to do to sell them to everyone and not just people who mod them. But as soon as you start putting performance exhaust, headers, taking away the cats ect. you start hearing it breathe and pop :D

I have no idea what you mean by "it backfires on heavy accel at 70, just 70 and nowhere else? Are we talking a little pop or a full on BANG like a backfire?

Yes, I quoted myself. Dont even say it...

If your going WOT and then let off, its going to pop.

Hell, to add to my first post.... My car does the same thing even with cats, just cant hear it as well.

[twcblackhand6970]

What about while I'm coasting at about 70mph or so, and I press the gas to accel or keep constant speed I hear it pop just as I open the throttle.

[Fixxer99TA]

Right, same idea there. The ones coming off WOT are louder though.

Dont be worried about it, LT1s like to pop with straight pipe.... If you dont like it, put those cats/manifolds back on :D

[twcblackhand6970]

No, lol, still not what I'm trying to say. When I press the gas from coasting. Like say I'm going 70 and let off the gas, then after I coast for awhile I press the gas again <<< My exhaust will pop just a i press the throttle to accelerate.

[enjoi355]

i know what you mean, its a really small one but it still can be heard

[twcblackhand6970]

mines about 3 or 4 small ones.

[enjoi355]

i guess its normal for lt1s then since more people experience it than i had previously thought