Ignition Timing: Testing and Inspection

Ignition Timing Inspection

1. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC).
2. Turn the ignition switch ON (II).
3. Make sure the HDS communicates with the vehicle and the powertrain control module (PCM). If it doesn't, troubleshoot the DLC circuit.
4. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
5. Check the idle speed.
6. Jump the SCS line with the HDS.




7. Connect the timing light to the service loop (white tape).




8. Aim the light toward the pointer (A) on the cam chain case. Check the ignition timing under a no load condition (headlights, blower fan, rear window defogger, and air conditioner are turned off).
9. If the ignition timing differs from the specification, check the cam timing. If the cam timing is OK, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the system work properly, and the PCM was substituted, replace the original PCM.
10. Disconnect the HDS and the timing light.