So I have been tuning for quite awhile and have done a lot of LS cars. I have noticed it mostly on the LS2 (05+) GTO's. After a flash I have to cycle the key and then when the car starts it runs rough with no response to throttle inputs. This happens for 3-5 ish seconds. I have noticed it on 98-02 f bodies also. My car (00 Z28 w 02 3 bar SD OS) has to be started with ether after a flash, or do the 30-50 starts and play with the pedal trying to get the car to stay running. After the 5 ish second delay the car runs normal and responds fine to throttle inputs.
Anyone have any ideas on what causes this? Seems to be the ecu is in some sort of default boot mode, with no response to throttle inputs.