Checks
| Actions
|
DEFINITION: Fuel ignites in the intake manifold, or in
the exhaust system, making loud popping noise.
|
Preliminary
Checks
|
|
Sensor/System
|
• | Inspect for the following intermittent ignition system conditions: |
- | Intermittent 24X CKP signal |
- | Intermittent ignition feed circuit or sensor ground circuit to
the crankshaft position sensor or the camshaft position sensor |
- | Intermittent 3X reference signal |
- | Intermittent camshaft position signal |
• | Inspect the mass air flow (MAF) sensor conditions. Ensure that
the MAF sensor honeycomb is not damaged. |
|
Fuel System
|
• | Ensure each injector harness is connected to the correct injector/cylinder. |
|
Ignition System
|
• | Inspect for proper ignition voltage output using the following
steps: |
- | Clip the J 26792
spark tester to engine ground. |
- | Connect one end of a spark plug wire to the J 26792
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 J 26792
spark tester. A spark should be observed. |
- | Repeat the above steps for each coil. |
• | If adequate spark is not present at the coils, inspect for the
following conditions: |
- | Coils--Cracks, carbon tracking/arcing or a resistance value
outside the specified range. |
Coil Resistance 5K-7K ohms (5,000-7,000 ohms). - | Spark plug wires--Signs of arcing/cross firing, cracks,
carbon tracking, plug boot damage, pinched, improper routing or a resistance
value outside the specified range. |
Spark Plug Wire Resistance 1 968 ohms per meter (600 ohms per foot).
| Important: : Spraying the secondary ignition wires with a light mist of water may
help locate an intermittent problem. Ignition components will arc to ground
when a secondary component is faulty.
|
- | Ignition system wiring--Loose ignition module feed or ground
connection, or damaged system wiring |
• | Remove the spark plugs and inspect for the following: |
- | Burned or damaged electrodes |
- | Improper heat range or reach |
• | If the spark plugs are gas or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
|
Engine Mechanical
| Check engine mechanical for the following:
• | Sticking or leaking valves |
• | Excessive oil in combustion chamber--Leaking valve seals |
• | Low cylinder compression |
• | For incorrect basic engine parts--Inspect the following: |
|
Additional Checks
|
• | Inspect intake and exhaust manifolds for casting flash. |
• | Inspect the exhaust system for possible restriction: |
- | Inspect the exhaust system for damaged or collapsed pipes. |
- | Inspect the mufflers for heat distress or possible internal failure. |
|