Ignition System Checks
| Check for a cylinder misfire:
- Start the engine.
- Allow the engine to stabilize.
- Disconnect the idle air control (IAC) motor.
Notice: Do not perform this test for more than 2 minutes in order to
prevent damaging the catalytic converter.
- Perform the Cylinder Power Balance Test with a scan tool.
- If there is a RPM drop on all cylinders, equal to within 50 RPM,
refer to
Rough, Unstable, or Incorrect Idle and Stalling
.
- Reconnect the IAC motor with the ignition OFF.
- If there is no RPM drop on one or more of the cylinders, or excessive
variation in drop, check for spark on the suspected cylinders with a J 26792
spark tester or equivalent.
- If there is no spark, refer to
Ignition Relay Diagnosis
.
- If there is spark, remove the spark plugs in these cylinders and
check for the following conditions:
- | Check the spark plug wire resistance. The resistance should not
exceed 30,000 ohms. |
- | Check the distributor rotor and the distributor cap. |
- | If the previous check did not find the problem, visually check
the following items: |
• | The ignition system for moisture, dust, cracks, burns, etc. |
• | With the engine running, spray the plug wires with a fine water
mist to check for shorts. |
|