Idle Speed

NOTE: Before adjusting idle speed, ensure MIL has not been reported on, ignition timing is correct, spark plugs are in good condition, air filter is clean and PCV system is functioning properly. On vehicles with daytime running lights, set parking brake, start engine and ensure that headlights are off.

Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Attach tachometer to tachometer test connector (2-pin with cover) located in right rear of engine compartment.
Disconnect Idle Air Control (IAC) valve 2-pin connector. If engine stalls, restart engine with accelerator pedal slightly depressed. Run engine at about 1000 RPM until engine speed stabilizes. Slowly release pedal until engine idles. Check idle speed under no-load conditions (headlights, blower motor, rear defogger, cooling fan and A/C are off). If necessary, adjust idle speed by turning idle adjusting screw. See Fig 1 . See IDLE SPEED SPECIFICATIONS . Ensure timing is correct. If timing is not correct, repeat idle check procedure.
Turn ignition off. Reconnect IAC 2-pin connector. Remove BACK UP (RADIO) fuse from underhood relay box for 10 seconds to reset PCM. Restart engine and let idle for one minute. On vehicles with daytime running lights, set parking brake and ensure that headlights are off. Check idle speed (after PCM reset) under no-load conditions. Idle speed should be stable and within specification. See IDLE SPEED SPECIFICATIONS .

Idle engine for one minute with headlights on low. Check idle speed. Turn headlights off. Idle engine for one minute with blower motor on HIGH and A/C on. Check idle speed. Idle speed should be stable and within specification. See IDLE SPEED SPECIFICATIONS . If idle speed is not within specification, check for proper operation of idle speed adjustment, IAC valve, fast idle thermo valve, throttle cable and throttle body, and air cleaner. Also check vacuum hose connections. See procedures in the TESTS W/CODES and SYSTEM/COMPONENT TESTS article.

IDLE SPEED SPECIFICATIONS

Application

RPM

Odyssey/Oasis

⁽¹⁾⁽²⁾⁽³⁾ 500-600

⁽¹⁾⁽²⁾⁽⁴⁾ 650-750

⁽¹⁾⁽²⁾⁽⁵⁾⁽⁶⁾ 720-820

⁽¹⁾	USA models.

⁽²⁾	Canadian models.

⁽³⁾	With Idle Air Control (IAC) valve disconnected, transmission in Neutral or Park and no load (headlights, blower motor, rear defogger, A/C and cooling fan off). On Canadian models, set parking brake and ensure headlights are off.

⁽⁴⁾

Turn ignition off and reset PCM by removing BACK UP (7.5-amp) fuse, located in underhood fuse/relay box for 10 seconds. With Idle Air Control (IAC) valve connected, transmission in Neutral or Park and no load (headlights, blower motor, rear defogger, A/C and cooling fan off). On Canadian models, set parking brake and ensure headlights are off.

⁽⁵⁾	Check after one minute with headlights on low.

⁽⁶⁾	Turn headlights off and check after one minute with blower motor on HIGH and A/C on.

Fig 1: Locating Idle Adjusting Screw (Typical)

Courtesy of AMERICAN HONDA MOTOR CO., INC.