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: |
| - | An intermittent crankshaft position (CKP) 18X Signal. |
| - | An intermittent ignition feed circuit or sensor ground circuit
to the CKP sensor or the camshaft position (CMP) sensor. |
| - | An intermittent 3X reference signal. |
| - | An intermittent CMP signal |
| • | Test the mass air flow (MAF) sensor conditions. Ensure that the
MAF sensor honeycomb is not damaged. |
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Fuel
System
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Ignition
System
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| • | Test for proper ignition voltage output using the following procedure: |
| - | 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 connected 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. 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: |
| - | Inspect the coils for cracks, carbon tracking/arcing, or a resistance
value outside the 5000 - 8000 ohms range. |
| - | Inspect the spark plug wires for signs of arcing/cross firing,
cracks, carbon tracking, plug boot damage, pinched wires, improper routing,
or a resistance value other than 600 ohms per ft. (1968 ohms
per meter). |
| | Important: Spraying the secondary ignition wires with a light mist of water may
help locate an intermittent problem. Ignition components arc to ground when
a secondary component is faulty.
|
| - | Test for a defective module. |
| - | Inspect the ignition system wiring for a 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 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
|
| • | Test or inspect the following engine mechanical components for
the following: |
| - | Test for sticking or leaking valves. |
| - | Inspect for worn camshaft lobe(s). |
| - | Inspect for bent push rods. |
| - | Inspect for worn rocker arms. |
| - | Inspect for broken valve springs. |
| - | Test for excessive oil in combustion chambers or leaking valve
seals. |
| • | Inspect for incorrect basic engine parts. Inspect the following: |
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Additional
Checks
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| • | Test the TCC operation. |
| • | Inspect the exhaust system for possible restrictions: |
| - | Inspect the exhaust system for damaged or collapsed pipes. |
| - | Inspect the mufflers for heat distress or possible internal failure. |
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