Engine lost its Brains
I crossed a threshold this week. After troubleshooting through several layers of problems, I finally got my motor running properly.
I first cranked it back in early March. It fired up on the first attempt, but then went into a very low rough idle mode and the throttle body would not respond to the e-accelerator pedal. After checking all the connectors, I read the OBDII codes using the Torque app on my cell phone with a Bluetooth OBDII reader. There was a list of codes as long as your arm and many of them were not even Chevrolet codes. Current Performance built my LS3 harness and flashed my ECM, so I called Jarad for help. Jarad suspected that something might be wrong with the program in my ECM, so I sent my ECM back to Current Performance. Jarad checked the ECM program to ensure all was OK. He found no problem and returned the unchanged ECM in April.
Needless to say, I had the same problems when I reinstalled the ECM. I suspected the Torque app I used to read the OBDII codes, so I bought a dedicated OBDII tester. Sure enough, the codes were all different. Now I was down to just half a dozen codes that pointed to the both the throttle body and the e-accelerator pedal. I already figured that, but at least the codes made sense now.
I suspected the e-accelerator pedal, so I checked to ensure the wiring was correct and then ordered a new one. I installed the new part and the OBDII codes related to the e-accelerator pedal went away. However, it still went into a very low rough idle mode and the throttle body would not respond to the e-accelerator pedal.
The diagnostic procedures for the remaining ODBII codes pointed more toward a harness problem than a bad throttle body, so I asked Jarad for a pin-out diagram.
There it was! The Throttle Position Sensor (TPS) was mis-wired in the ECM connector to pin 36 instead of pin 35. Now all codes are gone and the motor runs like a champ!

epper: