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Home >> Land Rover >> 1997 >> Defender 90 Automatic >> Repair and Diagnosis >> Engine Performance >> Engine Controls - Service & Adjustment Specifications >> Fuel System >> Base Idle Speed
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Base Idle Speed

NOTE: Before checking idle speed and mixture ensure air and fuel filters are okay. Check vacuum pipes and hoses for correct routing, leaks and/or restriction. Check ignition system for poor connections or loose wires. Perform repairs as necessary.

Check base idle speed using a Land Rover Test Book. On Discovery, ensure Idle Air Control (IAC) valve is set to 20-25 steps at idle. On all models, if necessary to adjust idle speed, locate by-pass screw in plenum chamber. Using a self-tapping screw, remove tamper-proof plug covering by-pass screw. Use Test Book to monitor idle speed while turning by-pass screw. Ensure there are no loads, the transmission is in Park or Neutral and air suspension (if equipped) is in standard position and disabled. Install NEW tamper-proof plug over by-pass screw after rechecking idle speed.

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