jss06c6

Just passing on some info for everyone dealing with a lean pop in their exhaust when shifting. Mine only showed up when I installed a Lingenfelter exhaust valve override switch (shift **** version) and drove with the butterflies open. Seems GM has the Clutch Fuel Cut Off (CFCO) set to kick in at 4mph and around 670 rpm (idle). Effectively engaged all the time. When shifting under load and high RPM, this does not show up, but shifting under light to moderate acceleration, say 2000 to 2500 rpm, mine always had an annoying lean pop on shift. Simple fix with HP Tuner... moved set point for CFCO enable to 80 mph and 3000 rpm. Problem solved. No more popping, just sweet LS9 sounds with bi-mode exhaust valves open...

whatcop?

Meh I like the pop especially when it includes flames.

K B Vettin

get to poppin

INTRCUL

I thought running rich was required to get the flames that whatcop? likes.

I also think a part of that sound is cavitation in the air flow and is more common with larger pipes (3" past the cats) and even more so when the flaps are kept open. The column of moving air goes massively turbulent during a shift with the valves kept open. Does anyone know if they close momentarily during a redline shift under load if you lift?

timmyZ06

I also love popping them, like SRT-4 style! I think the X-pipe exhaust instead of H-pipe does that!

Victory07

I kind of like the popping sound. It was the first thing I noticed when test driving my car when it was stock. It is even more pronounced now after removing the cats.

I was pulling out of the neighborhood the other day and had a neighbor behind me. He texts me 5 minutes later and says "Hey man your car is backfiring."

05dsom

Love the popping
Scares my neighbors 😄

PHPD7102

I have ARH long tubes high flow cats w/x pipe and Corsa catback, mine pops when shifting. After mine gets hot though it stops doing this.

billetman

Don't like it myself mine goes away when hot but I do wonder what harm it is doing uncontrolled explosions are never good.

narush

Mo pop the better and yes the flames are an added bonus

jss06c6

Certainly don't think it is severe enough to cause any problems. I've always tuned out the overly lean condition upon deceleration, but to each their own..

whatcop?

If I am correct the reason they go lean between shifts is to save your rings. You don't want fuel going into the cylinder without being ignited right away because it can get behind the upper ring and blow it out. That's the same reason you shouldn't run a car too rich.

jss06c6

Interesting.. That's why I set enable at 3,000 rpm and 80 mph, so that more aggressive driving would still allow CFCO to engage. Will give this some thought. Appreciate the input..

rocktober

i like it ,... sounds good

Bill Breski

I had it fixed, they changed the 2 codes then after 500 miles popping has come back. Same thing happened to my buddy

Breck

I like the back pressure pop!!!! The ZR1 saying "I'm still the KING!!!"

Bill Breski

can someone tell me how this could of happened both cars have hedders , high flow cats, low restriction air cleaners, and tune mine is 2013 the other one is a 2012 thx

jss06c6

?? Not sure. Mine is quiet. I do not have any mod's on the ZR1 though. I noticed it when I opened the butterfly valves with the LG man switch on my shift ****. Close the valves and no issue, open them and lean pop there at low/moderate shifts. With the change I made to the tune, the problem was eliminated.

C6Z06C6

Do you know what software was used to tune these cars?

Bill Breski

hp tuner