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Home >> Subaru >> 1998 >> Forester Base >> Repair and Diagnosis >> Engine Performance >> Engine Controls - Adjustments >> Idle Speed & Mixture >> Idle Speed
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Idle Speed

  1. Ensure air filter is clean, vacuum hoses are properly routed and connected, spark plugs are in good condition and timing is at specification. See IGNITION TIMING  . Verify malfunction indicator lamp (MIL) is not illuminated. Warm engine to normal operating temperature. Turn ignition off. Connect scan tool or tachometer (secondary pick-up type) following manufacturer's instructions.
    NOTE: Because spark plugs No. 1 and 2 fire simultaneously, some tachometers may register twice actual engine speed.
  2. Start and idle engine. Check idle speed with accessories off, then with A/C on. See IDLE SPEED SPECIFICATIONS  table. If idle speed is not as specified, check self-diagnostic system for DTC(s). Repair as necessary. See TESTS W/CODES article in this section.
IDLE SPEED SPECIFICATIONS

Application RPM
Forester
With A/C Off 650-750
With A/C On 800-900
Impreza
With A/C Off 600-800
With A/C On 750-850
Legacy
With A/C Off 600-800
With A/C On 800-900
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