jczz24

I have a 2009 SS/TC. I bought it in 2011 used at 15k miles with a GMPP Stage 1 reflash already installed by the dealership.

I installed a Hahn intercooler and Hahn CAI 2 years ago. I've also installed HIDs on it a year and a half ago, but that has nothing to do with the performance issues I'm having.

The car had never seen snow until this year. However this year, the car has decided to act stupid, and this is where I need some help.

Earlier this winter, on two different occasions, I left home and as soon as turning out of my neighborhood, I jumped on the throttle. On the 2-3 upshift, the car lost all power and the CEL started flashing as soon as I came off the clutch. Both times, I was at wide open throttle during the upshift.

The first time this happened, I coasted to my turn and while in the turning lane feathered the throttle to keep the car running. The engine was knocking like I spun a connecting rod. After doing this for a period of time, the car cleaned up, knocking went away, and I had power again like nothing happened. The CEL even went off.

The second time it happened, I held throttle just enough to keep it running and just coasted down the road. After the CEL stopped flashing, it stayed on solid and the car ran fine.

Now, both times this happened, the car was relatively cold and hadn't run in at least a few hours. The ambient air temp was below 40 degrees. The ECT the first time was around 100 degrees and the second time around 50 degrees. The second time when the CEL stayed on, I went to Advance Auto and ran the codes. I had a P0103, a P0300, P0302, P0303, and P0304. I cleared the codes and they haven't come back.

Last night, I went to leave and upon starting the car, it stalled immediately. I attempted to start the car 7 or 8 times and every time it stalled immediately. I tried to feather the throttle every time and the car started backfiring as it stalled. I finally held the throttle partially open while starting and it ran like ****, but remained running. I gradually brought it up to 2k RPM and held it there for a good while, til the ECT read above 150 degrees. However the entire time I held it there, it sounded like someone threw fire crackers in the tail pipe. After I brought it up above 150 degrees, I backed out of my driveway where it wanted to stall when I pushed in the clutch, and then I started down the street. It backfired almost the entire way down my street (my driveway is only a couple hundred feet at best from the stop sign). Once out on the main road, I jumped on the throttle. The car backfired a couple more times and then started running like it is suppose to, except its only running at 15psi when its suppose to be running at 20psi. The entire time this was going on, the CEL never came on. While sitting in the driveway trying to warm the car up, my A/F ratio gauge was steady at 14.5+/-, Cam Phase angle was at max on the gauge, spark advance was at 0 degrees, and boost was less than 0.

This isn't the first time it has had misfires on startup, but this is the worst it has been. The misfires on startup have been intermittent all winter long. Sometime it throws a CEL, but most of the time not.

I've been told to change out the plugs and boots, and to use brand name gas in it. But with less than 50k miles on the car, I find it hard to believe that the same gas I've been using in it is suddenly the problem or that it needs a tune-up already.

Has anyone else had a similar problem and if so, how did you fix it. This is my first forced air vehicle, however I'm no spring chicken. I've been around and worked on cars for 35 years, even raced a couple nitrous cars at the strip. I'm pretty versed in performance and performance modifications.

Again, any help or advice would be greatly appreciated.

tomj77

iTrader: (2)

Well ur first problem is ur raping on ur car while the engine is cold, that's pretty stupid. U can't do that on these cars and shouldn't in any car , u will almost alway get a flashing cel. Ur car is trying to protect itself from u destroying the engine. Let the bloody thing warm up before u punch it. Since u kept insisting on doing it it's possible u could have damaged something. But, try changing ur plugs. Check ur air filter, cause I'm sure it's wet and uv been sucking in moisture. Clean ur maf. That's what u get when u get a cold air intake, might I suggest a k&n or other short ram intake so u don't have that issue again.

So in conclusion, clean maf with maf cleaner, change plugs, check air filter and clean and dry if u need, and stop doing stupid crap like raping on a cold engine.

LNFTX

Very well said

To further that these cars dont run well cold, operating temp for most cars seems to be around 200. My car will hesitate buck and generally hate me if it sees boost at anything under 160. As far as the gas goes anytime they deliver a new load of fuel the possibility of getting bad gas exists, try another station for a couple tanks to rule out. Having to change the plugs at 50k is not out of the question especially if your hard on your car.

Devin86

Yeah I let my car warm up to atleast 100-125 befor even driving it then baby it until 160. Try not to bang on it under 40° too boost and cold air make engines go boom, lucky u are not tuned and on gms, your engine wouldn't have lasted this long.

tomj77

iTrader: (2)

ya cold air and boost wont make ur car go boom unless ur engine is already on its way out. turbos love cold air, make more power, not that much more that ull kill the engine.

jczz24

Sorry for the late update, but this problem has been solved. The aftermarket intercooler tanks had been hitting the pinch welds on the bottom of the subframe assembly where the steel front bumper frame bolts on. Apparently, over time, it kept bending the tanks like a punch until it punched a hole in both tanks. It only took 2 years to find the issue, but it was found about a year ago. I had the holes in the tanks welded shut and bent the pinch welds on the subframe assembly up and out of the way with a hammer giving me about an extra inch of clearance.

Logan Van Roy

I had random misfires under 60mph for months to where it wasn't comfortable to even drive and we couldn't figure out the problem. We replaced everything from fuel to electrical and exhaust/intake. Finally a light came on for abs and esc service. We replaced the wheel bearing and wa la it was fixed the second i drove it after that. We believe it had a bad wheel sensor that told the cu it was spinning causing the ecu to say hey traction control kick in which intentionally misfires the engine so you can regrip the road. Just a suggestion for the running rich at cruise code and/or service abs traction and esc codes. Even no codes at all except random misfires as it took forever for the wheel code to pop up.