Idle Speed

Idle speed is controlled by ECA and idle speed control air by-pass valve on all engines. If control system is operating properly, engine idle RPM is fixed and cannot be changed by standard adjustments. Manufacturer does not provide RPM specifications for many engines. A Scan tool must be used on these systems because control strategy and idle speed specification are controlled by ECA. See appropriate ADJUSTMENTS article in the ENGINE PERFORMANCE Section.

Before performing idle speed adjustment procedure, complete a thorough basic inspection and self-test (KOEO, KOER, Continuous Memory self-tests) to confirm operation of sub-systems contributing to idle speed control. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section.