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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| • | Refer to Important Preliminary Checks. |
| • | Refer to Visual/Physical Checks. |
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Sensor/System
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| • | Test 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 |
| • | Inspect 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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| • | Test 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 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: |
| - | Coils -- Cracks, carbon tracking/arcing, or a secondary resistance
value outside the specified range. |
Coil Resistance
5,000-8,000 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
600 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 inspect 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
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- Test and inspect engine mechanical:
| • | Sticking or leaking valves
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| • | Excessive oil in combustion chamber -- Leaking valve seals
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| • | Low cylinder compression
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For incorrect basic engine parts -- Inspect the following:
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Additional Checks
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| • | Test exhaust system for possible restriction. Inspect the following: |
| - | Inspect exhaust system for damaged or collapsed pipes. |
| - | Inspect mufflers for heat distress or possible internal failure. |
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