Burbling and Backfires

[FLORIT]

Wasn't sure which forum to post this thread, but it sounds like a tuning issue.

When I rev the engine, the exhaust "burbles" and "pops" as the RPM comes down. It also happens when I downshift while approaching a stop. And one time I actually heard a BACKFIRE when accelerating up a hill.

Is this normal? If so, how is that explained? If not, I will have the dealer take a look at it on Monday when they install the "thunk in the trunk" fix.

[bclarke]

Mine does it too, and I would think its normal for a high flow exhaust.
The SLP exhaust on my GrandPrix GTX does too, and its an auto.

Have you ever seen a road race in person? (SCCA) all the cars do it when decelarating.

[COSMO GUY]

:bubbrub Florit, Mine has done the same. I have an A4. Specially going down a mountain grade shifting from "D" into#3 gear to hold the car back.

COSMO

[Rocket]

Mine often makes a huge gurgling backfire as I decellerate around 1,500 rpm. I love that! :)

[mistermike]

Mine gurgles about 1/2 hour after hitting the drive-thru at Taco Bell. No backfires, at least not with the windows up. :eek:

[svede1212]

Mine gurgles about 1/2 hour after hitting the drive-thru at Taco Bell. No backfires, at least not with the windows up. :eek:

:D :D :D

[nikivee]

The exhaust was designed that way. The old GTO's would do the same thing on decelaration.

[RAZRS EDGE]

Just about all V8's will do that with a high-flowing exhaust. My truck does it, mothers WS6 does it.....

[speed_demon_freak]

I thought the cross over exhaust was to stop that?

[FLORIT]

OK, I like the sound of it, too, but I wasn't sure it was "normal". Now that I know why it happens (high flow exhaust) I am more comfortable. Thanks for the input, folks.

[derf]

The "crossover pipe" in our exhaust isn't actually functional. It's really just a cross brace to hold the pipes together at that point. There is no connection between either side of the duals. The disconnected duals don't "balance out" like when you have an H, X or Y pipe connecting the two. Without any balance between the pipes, it burbles like that. The old GTO never had a cross pipe and it did that kind of burbling too. They made it that way on purpose.

[Adam4356]

It's normal. Lack of crossover and highflow mufflers are the cause.

X pipe will help

[RA7 GTO]

Its normal. I read an article where either Wangers or Lutz or somebody very much "in-the-know" was bragging about how the GTO really "racks the pipes" when you decelerate in gear or downshift. Enjoy.

[MattSaint]

It is a very satisfying sound, to say the least!!! :)

[CMNTMXR57]

It has nothing to do with the exhaust other than it being audible because of the better factory exhaust system.

It has to do with the camshaft. Every LS1 I've ever seen does this. It's the nature of the ramp speeds and lobe separation. In older pre-PCM days, it could also be caused by timing issues. But since our PCM controls all timing, it's a function of the cam.

Cammed LS1's do it more and are even more satisfying. :D

[low_lai]

even my ld 5litre holden calais does it twin 2.5 into single 3" and no mufflers might have helped me out...