Backfiring...

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:

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. ?

most likely

"ORY to straight pipe"

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

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

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.

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

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

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.

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?