Checks
| Action
|
DEFINITION: The fuel ignites in the intake manifold, or in the exhaust system,
making a loud popping noise.
|
Preliminary Checks
| Refer to Important Preliminary Checks in
Symptoms - Engine Controls
.
|
Ignition System Checks
|
| | Important:: A higher secondary ignition voltage is required to operate the vehicle on
CNG than on gasoline.
|
| • | Inspect for proper secondary ignition system voltage output using only the
J 26792
spark tester. |
| • | Remove and inspect the spark plugs for the following conditions: |
| • | Test for proper ignition system operation. |
| • | Test for crossfire between spark plugs. Test for spark plug wire failure.
Wetting down the secondary ignition system with a water spray bottle may aid in
locating damaged or deteriorated components. |
|
Engine Mechanical Checks
|
| • | Inspect the engine for the following: |
| - | Proper engine cylinder compression |
| - | Sticking or leaking intake or exhaust valves |
| • | Inspect the intake and exhaust system for casting flash. |
|
Fuel System Checks
| Perform fuel system diagnosis. Refer to
Fuel System Diagnosis
.
|
Additional Checks
|
| • | Review service bulletins for PCM programming updates. |
| • | Verify that the correct CNG software and calibration has been programmed
into the PCM. |
| • | Test for proper operation of the AFO Enable circuit. |
|
