Idle Speed, Checking

ECM 8A0 906 266B has Oxygen control learning capability, which allows for the deletion of the CO potentiometer in the Mass Air Flow (MAF) sensor. As a result of this technical change, CO content can no longer be manually adjusted. For testing the mass air flow sensor several changes have resulted relative to the mass air flow sensor with CO potentiometer.

Requirements:

^ Exhaust system must be leak-tight

^ Engine coolant temperature must be min. 85°C(185°F)

^ Throttle must be in closed throttle position, if NO, adjust throttle cable, -> Repair Group 20.

^ All electrical consumers must be switched OFF

^ A/C system must be switched OFF

^ Do NOT have any pressure measuring devices connected

^ Place transmission selector lever in P or N position

^ Ignition switched ON


IDLE SPEED, CHECKING

Caution
The 3A card (or later) must be ins tailed In the VAG 1551 scan tool before performing the following checks.

Idle speed CANNOT be adjusted. Idle speed is checked during engine basic adjustment.

- read Diagnostic Trouble Code (DTC) memory using VAG 1551 scan tool.

- start engine and let idle.

Caution!
Do NOT take any readings while radiator cooling fan is running.

- press 0 and 4 buttons to select function 04.

- display group 03 and observe value in channel 1.

^ must be 700-800 RPM

If specific value NOT obtained

- read DTC memory again, -> Repair Group 01 (Fuel and Ignition) for additional information.

If idle speed RPM is too high and there are no codes stored in DTC memory, perform the following checks:

- check closed throttle switch, -> Repair Group 24.

- check for excessive infiltrated air (leakage in).

- check Idle Air Control system check valve, -> RepairGroup24.

- check learn values for Idle Air Control system, see basic adjustment of engine -> page 5.

If idle speed RPM is too low and there are NO codes stored in DTC memory, perform the following checks:

- check closed throw switch, -> Repair Group 24.

- check Idle Air Control system check valve, -> Repair Group 24.