pcmhacking.net

Just to update & find out if it's common, I did a flash today & just changed 3 bytes & of course it had the wrong check sum, but could wait an eternity & re-connected no worries, but after I flashed it in the first time it fired up it ran at 1500 rpm for 1 minute then I tried tapping throttle & changed gears(auto) & no goo so took it for a drive around 2 minutes & after putting it back to park or neutral it then idled at 2000!

I thought bugger but persisted & cranked & started & let run for around 10 seconds 3 times & on the 3rd attempt it finally just went back to normal idle position!

Have others experienced this?

I also tried just making these changes to the exact same tune DMTY $BD on another pcm & just swapped the pcm's & it started & ran initially but then wouldn't crank/fire again & I did an AA06 for the check sum when I made the 3 changes but guessing I must have to do something else if I wanted to use the same tune/pcm even if out of a different vehicle but thought if I A06 the check sum it would by-pass it?

AA06 for the checksum will just mean it will get a CEL from a bad checksum, need to change the device ID to AA to bypass it.

sorry I just worded what I did wrong!

attached is the file I flashed in & thought with AA06 the ID would be able to swap the pcm & would just disable the security?

Has anyone else flashed in he exact tune with minor differences & had the high idle for next few start up's?

It might have been that the PCM did not reset properly after the flash process and had what it would see as corrupt RAM - the flash bootloader runs from RAM so overwrites lots the PCM items such as idle IAC learning. The last step of the process is to erase it all, then force a PCM reset afterwhich the PCM should detect a RAM checksum issue and initialise it all as default values - maybe the default IAC steps caused the idle to be really high until it learnt the correct value again? If it happens again get a log and see whats going on