Checks
| Actions
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Definition:
Fuel ignites in the intake manifold, or in the exhaust system, making loud
popping noise.
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Preliminary Checks
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Sensor/System
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| • | Check for the following intermittent ignition system conditions: |
| - | Intermittent CKP 24X 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. |
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Fuel System
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| • | Ensure each injector harness is connected to the correct injector/cylinder. |
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Ignition System
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| • | 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 crisp blue
spark should be observed. |
| - | Repeat the above steps for each coil. |
| • | If adequate spark is not present at the coil(s), check for the
following conditions: |
| - | Coil(s) - Cracks, carbon tracking/arcing, or a resistance value
outside the specified range. |
Coil Resistance
5000 - 7000ohms (5K - 7Kohms) | - | 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
7000ohms (7K ohms)
| | 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.
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| - | Ignition System Wiring - Loose ignition module feed or ground
connection, or damaged system wiring. |
| • | Remove spark plugs and check for the following: |
| - | 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
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| • | Check Intake and exhaust manifold(s) 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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