Problems at cold start up with 2000 SS
 

So out of nowhere my 2000 SS decided to start having problems yesterday. I went to start the car in the morning to head to work and cranked it over and it fired and stalled out. Did it again. So I cranked it over and then started feathering the gas pedal to keep it running. After about 10-15 seconds it suddenly found the normal idle and kept running. At that point the exhaust was super rich, probably from me pedalling it. So on the way to work I noticed a high pitch whine coming from the speakers, but the stereo wasn't even turned on. You could hear it change with the engine speed. Then right in front of work, all my indicators on the dash popped on and then blinked out. The air bag light started flashing. That repeated itseld when I pulled into the parking lot. So when I tried to leave work, I cranked it and it just clicked, didn't even crank over. I tried 3 times and then it cranked over and did the same stall out thing. I had to feather it like I did in the morning until it found idle by itself. Same high pitch whine from the speakers on the way home too. I put it in the garage and decided to clean the battery cables, post and bolts. Then I put it on the charger overnight thinking maybe it was a weak battery. The battery is just over 2 years old so I don't think it's that. Then today after work, I wanted to put it on the ramps in case I needed to pull the alternator. I start it up and the same stall out thing. But because I had disconnected the battery it seemed to take longer for the car to finally find a normal idle this time. And when I hit the gas pedal it would bog. I was checking the car with the scanner and nothing really looked out of whack and there are no codes. After about 5 minutes of running it seemed to be fine and revved up like normal. But now there is no high pitch whine from the speakers. I won't get a chance to check all the wiring under the car until tomorrow when I try a cold start again. Since the O2's aren't used at cold start up I don't think they are part of the problem. Could it be EGR stuck open? AIC stuck? MAF going bad? Leaky injector? Clogged cat? I don't think it's electrical like I first did. Car is a 2000 SS with A4, longtube headers with AIR and EGR, lid, ported TB, PCMforless tune, MSD wires, dual 3" cats, rear O2's tuned out. Something seems to be giving the computer bad information until it warms up some. Any thoughts?

Well, I would think MAF or EGR causing the car to run that poorly would throw a code?

Do you have a fuel pressure gauge? IC also sounds possible. Also check you hoses for a leak. Some times colder weather will cause a hose to leak more then in the warm weather.

well if you wanna toss out if its a bad egr i have one sitting in the garage from my 98. im tired of looking at it lol

my first guess whould be the MAF

Bad coolant temp sensors do funny things at start-up too.

thats is true also start up for the first 8 or so seconds is based of Start up enrichment wich is based of ECT

yeah.... ect !!!

normally a big problem with yotas & other forien cars but does go bad on occasion w/ american built

i would put the scanner on after it sitting over night and before starting and compare IAT with ECT. if they aren't within 4 degrees of each other, there is an issue there.

i was also thinking tps. it may be fluctuating too fast for your scanner to see it.

I disconnected and reconnected all the wiring to the sensors, pulled out the IAC and cleaned it but it wasn't really dirty, cleaned the TB, swapped out the EGR for a spare I had sitting around and it started up fine like nothing was wrong. The IAT and ECT were the same at 59. I'll just have to keep an eye on it when/if it acts up again. If it was the EGR, then I should be fine for while with the spare.

delete mod on that egr

Car started up fine again today. The ECT and IAT were about 4 degrees different as well.

yeah thats the limit. if its more than 4, you have sensor issues.

Car was fine this morning but I was looking at the scanner again and now I see some stored high and low voltage codes for the ECT circuit.