Rover Resources Center
Range Rover Classic | '87-'88
Routine idle speed adjustment during maintenance services is not necessary nor desired. If your idling speed is off, it is often the result of another problem. The bypass air valve (stepper motor) located at the rear of the plenum chamber receives signals from the EFI's electronic control unit and automatically corrects hot idle speed within a range of 665-735 RPM. Use of air conditioning will raise the idle speed slightly above the normal range. This is acceptable.
Problems such as idle surge, excessively high or low idle or off idle hesitation can usually be traced to one or more of the following:
Use the Workshop Manual, Lucas handheld tester and other shop diagnostic equipment to isolate and correct any of the above problems.
If the above checks, repairs or adjustments do not solve the problem, the base idle speed should be adjusted. IMPORTANT: All steps must be followed in sequence exactly as listed below. DO NOT attempt this procedure unless the basic throttle/timing/potentiometer adjustments have been made (see Workshop Manual - Section 19).
With the engine at operating temperature and an accurate tachometer connected:
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