E37 T42: First cold start of the day, starts and stalls, restarts strong

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Got an issue with my 2009 Pontiac G5 2.2l LAP, 4T45E automatic transmission. Controllers E37 and T42.


Every morning at or below -10C, the car will start, flare up and stall on it's way back down to target idle speed. 2nd restart is healthy.

At the same times, I have been experiencing a platitude of communication codes. U2100, U2105, U2106, U2107, U0073, P1501, etc ,etc

I found and repaired wiring at the DLC (where a remote start install was previously attempted) currently wiggling the dlc does not cause any issues with nothing plugged into port.

Once I plug something into my OBD port, the car has a tendency to act up, whether its my hptuners cable or another scanner. At his point, I don't think wiring is an issue.


I have noticed when I stall, the car is going really lean. and I actually just spotted today, that when I am stalling, the car is trying to start in 1st gear rather than what it regularly uses, 2nd gear.
I'm at a point where I could either throw a ECU or PDC at it but I'd like to have a little more direction first.

I've checked every fuse, cleaned and rewired most grounds, I've tried starting the car without a scanner plugged in, etc I need help. Tune has worked for years with minimal changes to WOT timing. Now at a loss

Car has 60's injectors, LS4TB, CAI, M62 supercharger..

Vats is turned off, fuel pressure reads 50psi key on (after sitting all night) 60psi running. Fuel pump power is fed directly from battery.