Rick Voss

I have a 06 vert, non Z51, M6, with APS twins, and APS 3” exhaust. It is backfiring badly on decal. If I run the RPM’s up to 4500 or more it is really bad. Enough so I think it would blow the seams out of a stock muffler. The APS system is so strongly built I think / hope it can handle it! At this point I will only drive the car for diagnostic purposes to correct the issue. The tuner has been awesome. The specs from the dyno at installation are 565 RWHP, and 577 RWT. with 8-9 lbs of boost. All the fuel trims and timing looks spot on. He compared the tune to all the other APS installs they have done (7 or more), and everything looks right. They have not had this issue with any of their other installs. The tuner drove over thirty miles with me yesterday with his lap his top, spending hours to check all the specs and trims, and could find nothing wrong. The tuner is researching the problem this weekend, and has offered to come to my house (152 miles round trip) to try and correct the problem once his research is complete. What incredible customer service! I am thinking I have one bad injector that is leaking, and it only happens on decell, when the throttle is suddenly shut, the manifold vacuum soars to its highest spec, drawing fuel out of the faulty injector, causing a rich mixture, and the overly rich condition is burning / back firing in the exhaust.
Any ideas on this would be greatly appreciated. Spring is here and I want to drive my car!

Thank you in advance for any input.

RV

turbo_tom

I think it's normal, Rick. All the modified turbo cars I know do it as well... Unless it is as loud as a gun shot/ firecracker, constantly, I don't know...

booztedz33tt

thats normal with a full exhaust or at least no cats, if its a rumble back fire when you down shift no worries

FastBlackTA

Mine does this too. I personally thought it sounded pretty awsome

Rick Voss

Tom,
Your description of "as loud as a gun shoot or firecracker" is a good one, its that loud, I am sure its not normal. The tuner who rode in the car agrees it not normal, and the other APS units with 3" APS full exhaust aren't doing it. Hopefully he will find something.
Thanks
RV

DSOMC6

I have the same set-up ie: APS TT, APS 3" exhaust. I have had this happen on decel occasionally, however not as often as you describe. Unburnt fuel is probably the culprit, and I think the tuner is on the right track. Keep us informed as to what you find out.

Brabus2

Under decel with the cats I get the burble, with the off-road midsection (non cats) I occasionally get backfire as loud as Tom described "gun shot or firecracker".

JJSC6

I have heard this too!!!

I don't particularly like it, but it is, what it is.

Heh heh, and you turbo guys thought your systems were "bulletproof"??

Don't get excited, at least Voss is "catching his issues" and reporting them!!!

I don't particularly like the "clanging" of the turbo mechanics on that system either, but the system is cool, it's just like every other system. It has it's issues too!!

Good luck. Post up any resolutions!!!

0APS

If you have back firing on decel you have a tuning problem, not a turbo system problem. There is an adjutment in the HP tuners software which allows the for minimum injector duty cycle on decel to be decresed. If you have this min inj duty cycle set incorrectly you will definitey hear/experience some big back fires on decel as the injectors will not completely shut causing a rich air fuel ratio condition when the engine should be seeing a leaner air fuel ratio condition.

Best get back to your tuner to have this adjustment resolved.

Peter