Checks
| Actions
|
DEFINITION: Fuel ignites in the intake manifold, or in
the exhaust system, making loud popping noise.
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Preliminary
Checks
|
| • | Refer to Important Preliminary Checks in
Symptoms |
| • | Refer to Visual/Physical Checks in
Symptoms |
|
Sensor/System
|
| • | Check for the following intermittent ignition system conditions: |
| - | Intermittent CKP 18X 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 |
| • | Check the mass air flow sensor conditions. Ensure that the MAF
sensor honeycomb is not damaged. |
|
Fuel System
|
| • | Ensure each injector harness is connected to the correct injector/cylinder. |
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Ignition System
|
| • | Check 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 spark should
be observed. |
| - | Repeat the above steps for each coil. |
| • | If spark is not present at the coils, check for the following
conditions: |
| | Important: If carbon tracking is detected on a component, replace that component
and its mate.
|
| - | Coils - Cracks, carbon tracking/arcing, or a secondary resistance value
outside the specified range. |
Coil Resistance
5000 - 8000 ohms (5K - 8K 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
1000 to 1500 ohms/per ft.
| | 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 spark plugs and check for the following: |
| | Important: If carbon tracking is detected on a component, replace that component
and its mate.
|
| - | Check the spark plugs for carbon tracking on the porcelain and pitting
on the plug wire contact. |
| - | Burned or damaged electrodes |
| - | Improper heat range or reach |
| • | If spark plugs are gas or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
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Engine Mechanical
|
| • | Check engine mechanical: |
| • | Sticking or leaking valves |
| • | Excessive oil in combustion chamber-leaking valve seals |
| • | Low cylinder compression |
| • | For incorrect basic engine parts. Inspect the following: |
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Additional Checks
|
| • | Check Intake and exhaust manifolds for casting flash. |
| • | Check exhaust system for possible restriction. Check the following: |
| - | Inspect exhaust system for damaged or collapsed pipes. |
| - | Inspect mufflers for heat distress or possible internal failure. |
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