I thought i would share some E38 PCM info that may or may not have been covered already to save the next guy the misery i went thru with a customers car. We retrofitted an LS3 into a 66 nova and based the system off of 2010 camaro components with a 2010 corvette gas pedal all supplied from the oufit that sells me custom wiring harnesses.
Its been covered before but do NOT flash a 2007-2008 E38 with a 2009-2010 OP system or it will corrupt the PCM and render it useless. NVRAM corrupts???
Avoid reflashing a PCM with a 2010 Camaro OP system unless the PCM actually started life as 2010 camaro. It has its own P/N on the E38 and is the bastard child of the E38's. Flashing a similar year E38 with 2010 camaro results in unfixable throttle issues and a dead pedal after about 5 jabs and plugging in TAC calibrations from any other model will NOT solve the issue. Avoid 2010 camaro OP system on a non stock reflash at all costs.
On my 2010 camaro based harness, any OP system besides 2010 corvette or camaro would result in a VSS reading of 158 mph and was also unfixable. The solution to my dilemma was to follow the recommendation of a local GM tech and flash my 2010 silverado based PCM to 2010 corvette OP system and it all worked flawless.
Even attempting to rewrite the throttle axis tables to remove the rather lazy corvette programming resulted in throttle blowout so to avoid headaches, use the TAC programming the OP system came with. Im sure there is more to this story that other can feel free to add to this info but this is a good start to understanding the damn E38.