I was driving into work yesterday, my GXP was running fine. It has thrown a secondary air valve trouble code a few times, setting off my SES light on the dash. Then the light would go out after a day or 2. Got to the Shell station to get my morning coffee, and it starts missing. The more gas I gave it, the louder it got. It's coming from the back of the engine. I'm thinking the Secondary air valve finally crapped out. The back 4 ignition coils were replaced last spring, as was all 8 spark plugs. The front 4 ignition coils are stock. No problems out of them yet.

Unless you're getting P0410, P0412 or P0418, I doubt it.

Secondary A.I.R. is only impacting engine operation upon initial startup (ECT has to be in the range of 41* - 176* and IAT >41*) and will shut off once closed loop operation is achieved. So once you're in closed loop, it isn't even part of the equation... It's basically extra weight the car is carrying around at that point.

Sounds like something else is the issue.

_________________


Retired Bonneville Owner and former GM Tech:
2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck

It was DEFINITELY something else!!! The #1 spark plug somehow backed out, and my coil was fried!!! Just put 4 new rear coils, and 8 new Autolite spark plugs in, at this time last year. I'll keep an eye on the spark and make sure it's still tight periodically.