Checks
| Actions
|
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. |
| • | Refer to Visual/Physical Checks |
|
Sensor/System
|
| • | Test for the following intermittent ignition system conditions: |
| - | An intermittent CKP 18X signal |
| - | An intermittent ignition feed circuit or sensor ground circuit
to the crankshaft position sensor or to the camshaft position sensor |
| - | An intermittent 3X reference signal |
| - | An intermittent camshaft position signal |
| • | Inspect the mass air flow (MAF) sensor conditions. Ensure that
the MAF sensor honeycomb is not damaged. |
|
Fuel System
|
| • | Ensure that each injector harness is connected to the correct
injector and cylinder. |
|
Ignition System
| Test for proper ignition voltage output using the following
steps:
- Clip the spark tester J 26792
to engine ground.
- Connect one end of a spark plug wire to the spark tester; leave
the other end of the spark plug wire to the coil being tested.
- Connect one end of another spark plug wire to the other coil tower;
connect the other end of the spark plug wire to ground.
- Crank the engine while observing the spark tester; a crisp blue
spark should be observed.
- Repeat the above steps for each coil.
- If spark is not present at the coils, test for the following conditions:
| - | The coils--Inspect for cracks, for carbon tracking or arcing,
or for a secondary resistance value that is outside the specified range. |
Coil Resistance
5,000-8,000 ohms (5K- 8K ohms) | - | The spark plug wires--Inspect for signs of arcing or cross-firing,
for cracks, for carbon tracking, for plug boot damage, for pinches, for improper
routing, or for resistance value that is outside the specified range. |
Spark Plug Wire Resistance
600 ohms per ft.
| | Important: Spraying the secondary ignition wires with a light mist of water may
help to locate an intermittent problem. The ignition components will arc to
ground when a secondary component is faulty.
|
| - | The ignition system wiring--Inspect for a loose ignition
module feed or ground connection, or for damaged system wiring. |
- Remove the spark plugs and inspect for the following conditions:
| - | Burned or damaged electrodes |
| - | Improper heat range or reach |
If spark plugs are gas or oil fouled, you must determine the cause of
the fouling before you replace the spark plugs.
|
Engine Mechanical
|
- Test and inspect for the following engine mechanical conditions:
| • | Sticking or leaking valves
|
| • | Excessive oil in the combustion chamber caused by leaking valve
seals
|
| • | Low cylinder compression
|
| • | Inspect the following engine components: |
| - | Other engine components, as applicable |
|
Additional Checks
|
| • | Test the exhaust system for possible restrictions. Inspect for
the following conditions: |
| - | Damaged or collapsed pipes |
| - | Heat distress or possible internal failure of the muffler |
|
