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Home >> Saab >> 1993 >> 900 Commemorative >> Repair and Diagnosis >> Engine Performance >> Engine Controls - Adjustments >> Idle Speed & Mixture >> Idle Speed

Idle Speed

  1. Ensure engine is at normal operating temperature. Ensure CO and ignition timing are correct. Locate dashpot and Idle Air Control (IAC) valve on throttle body. Loosen lock nut on throttle dashpot, and lower dashpot to clear throttle lever. Pull back rubber boot on IAC connector, and connect digital dwell meter leads to pin No. 3 and ground. Connect a tachometer.
    NOTE: DO NOT  make idle setting when radiator fan is operating.
  2. Unplug throttle position sensor connector. Connect jumper lead between pins No. 1 and 2 on harness side of connector. Inspect throttle position sensor and throttle cable for interference with movement of butterfly.
  3. Start engine. Ensure all accessories are off. On models without air bleed adjuster screw, loosen throttle stop screw lock nut. Turn adjuster screw counterclockwise until screw does not touch throttle linkage.
  4. On models with air bleed adjuster screw, loosen throttle stop screw lock nut. Adjust clearance between throttle butterfly and housing to 0.002" (0.05 mm). Loosen air bleed screw lock nut. Rotate air bleed screw clockwise until it is fully seated.
  5. On all models, dwell meter should indicate about 34 degrees. If dwell is not to specification, check for vacuum leaks. Rotate adjuster screw/air bleed screw until engine idle speed is 850 RPM.
  6. Dwell meter should indicate 32-35 degrees. Tighten lock nut on adjuster screw/air bleed screw. Turn engine off, and restore connections. Adjust throttle dashpot. See DASHPOT ADJUSTMENT  .
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