Honda - Accord Prelude 1996 2000

Idle Speed and Mixture Adjustment


Idle speed and mixture for all engines covered by this guide are electronically controlled by a computerized fuel injection system. The only adjustment possible is the warm idle engine speed. No other adjustments are possible.


Before setting the warm idle speed, the following items must be checked or verified:

The Malfunction Indicator Light (MIL) light has not been on or flashing
Ignition timing is within specification
Spark plug condition is within specification
Air cleaner condition is acceptable
Positive Crankcase Ventilation (PCV) system is functioning properly

On Canadian vehicles, the parking brake must be applied before proceeding with any adjustments.

  1. Make sure the heater is in the full cold position and all electrical consumers are in the off position, such as headlights, defrosters, climate control fans, and other electrical accessories.
  3. Start the engine and hold the engine speed to 3,000 rpm with the transmission in Park or Neutral , until the radiator cooling fan comes on, then let the engine idle.
  5. Connect a tachometer or the Honda PGM Testing Assembly.
  7. On 4-cylinder engines, detach the round 2 pin electrical connector from the Idle Air Control (IAC) valve.
  9. If the engine stalls, restart pressing the accelerator, hold the engine speed at 1,000 rpm, and slowly release the gas pedal until the engine idles.
  11. Check the idle speed making sure all electrical accessories are turned off, with the transmission in Park or Neutral .
  13. The idle speed should be 500-600 rpm
  15. If the idle speed must be adjusted, do not turn the adjusting screw located at the top left of the throttle body inlet side more than 1 / 4 of a turn a minute. Make sure no electrical accessories are operating when checking or adjusting the engine idle speed.
  17. On the 4-cylinder engines, once the correct test procedure idle speed is attained, perform the following:
    1. Turn the ignition switch to the OFF position.
    3. Reconnect the round 2 pin electrical connector to the Idle Air Control (IAC) valve.
    5. Remove the BACK UP (RADIO) 7.5 Amp fuse located in the under-hood fuse/relay box for 10 seconds to reset the Powertrain Control Module (PCM).