When working on a 2009 Cadillac CTS VIN 7, I want to set the idle to 850 rpm, for four very good reasons. On the Maxisys Elite under diagnostics/control unit/engine/special function/engine/engine speed control/, you can command the idle speed in 25 rpm's, starting at approximately 525 rpm, so you can bump it up to 850 rpm, however when exiting out of the procedure by tapping ESC, the idle goes back to approx. 540 rpm.
My question is how do you reprogram the ECM on the car to stay at 850 rpm?