Quote
...Diagnostic trouble code P0506, defined as "Idle control system RPM lower than expected"....

...But...with this method the pintle doesn't physically move but the ECM gets data from the IAC saying that it DID move. The perfect fake out...


Therein lies the problem , methinks.

The ECU will use the tachometer to measure the engine revs. If it detects no change in engine revs for a given change in IAC servo setting it will set a CEL as it gets to the end of its range of output to the IAC -"maxes out" (failure of the "closed loop" system)

My guess is there would be a predetermined idle revs for hot/cold/aircon/etc type situations programmed in to the ECU, and that the IAC is used to achieve this by increasing the revs from a baseline figure.


2002 Sporty , Ironman 2.5" spring, 2" body, 15 x 7 ROH wheels, K&N, 15 x 10.5 Simex Centipedes, Powerchip 91.

"Never argue with an idiot. They will bring you down to their level then beat you with experience!"