Setting the Idle Speed / Stepper Motor

If you have accidentally adjusted the idle screw or need to reset the stepper motor position for the ECU to determine the correct Idle Speed ther following procedure should be followed:

1 Engine warmed up (> 80C), Ignition On

2 Neutral position and handbrake applied

3 With the help of the diagnostic tool, close the stepper

4 Remove the connector from the IAC

5 Start the engine and let it idle.

You may need to put on some throttle to get it to work. Check the engine speed. You want the engine speed to be at least 125 rpm below the “target idle speed” specified in the chip. (850 RPM when warm)

Use the throttle screw to set the idle speed to 725 (125 below 850)

6 Turn off the engine. Connect the IAC connector.

7 Switch on ignition and press the gaspedal three times.

8 Switch off ignition.

9 Start the engine and let it run for 5 seconds, switch off the engine and wait at least 30 seconds.

10 Start the engine at idle. The idle speed should be close to the Chip set “target idle” when the IAC is controlled by the ECM.

Connect the scanner and check the IAC number. The steps should be between 20 and 30, but can vary and has a higher reading in higher altitudes or for a newly converted engines.

If outside of this range then adjust with the diagnostic device.
With the IAC counts, the ECU knows where the stepper motor isin relation to fully closed or fully open is located.

When the engine is stopped, the IAC will close completely and then open up to a specified number of counting increments to prepare for the next engine start.

11 Set idle rpm with diagnostics (not on the screw)

12 Save settings