Idle Mixture

NOTE: On Discovery Series I, idle mixture is controlled by GEMS through the ECM. On Discovery Series II and Range Rover, idle mixture is controlled by Bosch Motronic M5.2.1 engine management system through the ECM. Mixture is not adjustable, but should be checked as part of normal tune-up procedure using an exhaust gas analyzer. If vehicle is not within specifications, see SELF-DIAGNOSTICS article. Always refer to SERVICE INFORMATION underhood label in engine compartment. If underhood label and lemon-25® specifications differ, always use underhood label specifications. See IDLE SPEED & MIXTURE SPECIFICATIONS table.

IDLE SPEED & MIXTURE SPECIFICATIONS

Application

Specification

Base Idle Speed ⁽¹⁾

Discovery Series I

In Neutral With A/C Off

597-653

In Neutral With A/C On

672-728

Discovery Series II ⁽²⁾

610-710 RPM

Range Rover ⁽²⁾

660 RPM

CO @ Idle

Range Rover

⁽³⁾

Discovery Series I & II

Less Than 0.5%

⁽¹⁾	Idle speed is controlled by ECM through Idle Air Control (IAC) valve. With engine at normal operating temperature, IAC valve should be set to 20-25 steps.

⁽²⁾	In Neutral with A/C off.

⁽³⁾	Information not available from manufacturer.