Backfires while decellerating

[hamil66]

Just bought a brand new 2004 six speed convertible. Are they supposed to backfire everytime you let off the gas above 2500 to 3000 rpm? It is not completely broken in yet, just turned 500 miles. I am used to driving a six speed ZR-1 and it does not make any such noise. Is this a characteristic of the LS-1 engine with a manual transmission?

 

[yellow_2002_germany]

What you are hearing is not backfiring. I believe it has to do with the h-pipe arrangement between the exhaust pipes to help equalize pressure on each side. I have a corsa exhaust on my car and the sound you note is quite loud on my car. But I like it!

As far as I know the only way to quiet the sound if you don't like it is to add an x-pipe. With an h-pipe the exhaust gases have to make 2 90 degree turns to go from one side to the other. With an x-pipe the turn angle is much more gentle and the area connected between the pipes is usually much greater allowing for less pressure in the exhaust.

There are others who know a great deal more and will chime in soon.

 

[bluecoupe]

Not normal on stock pipes get it checked.

 

[Vanity Plate Bob]

Drove an 11,000 mile 03 ZO6 6 spd the other day and it popped a little.

 

[JasonFRC]

Not normal on stock pipes get it checked.

My 32k mile '99 does it too.

What should we check for? My car runs flawlessly, idles perfectly, power delivery is smooth.

 

[hamil66]

I have decided that it is normal. Just pops a bit when it is winding down. Matter of fact, I have decided I like it! The vette is fantastic is every way. Later, guys.

 

[JasonFRC]

I have decided that it is normal. Just pops a bit when it is winding down. Matter of fact, I have decided I like it! The vette is fantastic is every way. Later, guys.

I have to agree. I like it too.

I've heard other LS1 powered cars do it too, Camaro, Firebird...

 

[pvtpilot]

My 99 with 29K has always "rumbled" a little when downshifting ... love the sound. The unique exhaust sounds of Corvettes has always been a source of great enjoyment to me. My first was a 65 roadster with a 300/327. I can still hear the unique sound of that car. Fact is, back in those days I could probably identify most make and engine models while blindfolded because of the unique engine/drivetrain sounds. I may be a little old for some of the CAC members, but I can think of several unique sounds: C2/C3 exhaust systems, Muncie and B/W trannys, Two four barrels kicking in, Pontiac GTO's with three two's, 409/425's, Mopar starter motors, etc.. Plus, I hate to admit it, but I can also remember the unique sounds of some of the HP Fords..
Best, Glenn

 

[bluecoupe]

Rumble, gurgle or burble sound when letting off the throttle is normal. Backfiring (loud popping) in not normal. Un-burnt fuel hitting the hot exhuast system can cause damage in a car with a catalytic converter.

 

[kernelpanic]

I'd agree with yellow_2002_germany, having driven or raced no less than 10 different C5s including Z06s, the gurgle or popping was heard on all of them, usually accentuated if the car had an after market exhaust. I would definitely consider it "normal" for mostly stock Vettes. No Corvette "expert" that I've ever spoken with has considered it a problem.

 

[atmmac]

ive got it too it sounds good.

-Andy

 

[klymaxr]

You think you have popping !!! Try it with long tube Kooks headers,3" long "X" pipe (no cats) to a CORSA pace car/tiger shark tipped muffler!!! with thew lS-1 edit done this thing sounds like two super bikes drag racing when you let it go and on deceleration when down shifting it sounds like the 4th of july!!!
When cruising at 75-85mph it sounds incredible and is only slightly louder than stock...untill you get on it!!
max

 

[Patrick]

My Z06 makes that gurgling sound too, principally when I let off the gas and coast. Kind of a distinctive sound. In fact, at a recent "drive and dine" with my Corvette club, the guy behind me asked me at the next stop if that gurgling sound was normal. Mind you, I have borlas on my Z06, so at first I thought the aftermarket exhaust might have had something to do with. Glad to hear its fairly normal among other C5 owners.


Personally, I like the sound, too. Sort of a musical interlude to let you know that the Vette is just toying around with all the spare power it has. And it gets every bit the same amount of attention as the full exhaust at higher RPMs.
:cool

-Patrick

 

[cavettefan]

What you are hearing is not backfiring. I believe it has to do with the h-pipe arrangement between the exhaust pipes to help equalize pressure on each side. I have a corsa exhaust on my car and the sound you note is quite loud on my car. But I like it!

As far as I know the only way to quiet the sound if you don't like it is to add an x-pipe. With an h-pipe the exhaust gases have to make 2 90 degree turns to go from one side to the other. With an x-pipe the turn angle is much more gentle and the area connected between the pipes is usually much greater allowing for less pressure in the exhaust.

There are others who know a great deal more and will chime in soon.

Agreed (H-pipe causing the popping). I had popping with the stock exhaust. When I swapped out the stock exhaust for a Corsa Touring cat-back exhaust, I also replaced the stock H-pipe with a Corsa X-pipe - no more popping. Personally, you need to decide how much you like/don't like the popping sound.