Idle Speed & Ignition Timing

Ensure idle speed and ignition timing are set to specification. See IDLE SPEED SPECIFICATIONS and IGNITION TIMING . For adjustment procedures, see the ADJUSTMENTS article. Before checking or adjusting idle, ensure MIL has not been reported on, timing is correct, and that spark plugs, air cleaner and PCV system are okay.

IDLE SPEED SPECIFICATIONS

Application

RPM

Prelude

⁽¹⁾ 500-600

⁽²⁾ 650-750

⁽³⁾ 720-840

⁽¹⁾	Canadian models.

⁽²⁾	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.

⁽³⁾

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.

IDLE CO LEVEL

Application	CO Level
Prelude	0.1%

FAST IDLE SPEED SPECIFICATIONS

Application	RPM
Prelude	1200-1600

IGNITION TIMING - Degrees BTDC - RED MARK @ RPM

Application	Specification
Prelude	13-17 @ 650-750