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 CKP Sync or 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 throttle body inlet screen for foreign objects or
damage that can affect the MAF sensor airflow sample. |
|
Fuel System
|
|
Ignition System
|
| • | 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 spark should
be observed. |
| - | Repeat the above steps for each coil. |
| • | If adequate spark is not present at the coils, test for the following
conditions: |
| - | Coils - Cracks, carbon tracking/arcing, or a resistance value
outside the specified range. |
Coil Secondary Resistance
5000 - 8000 ohms (5K - 8K ohms) | - | Spark plug wires - Signs of arcing/cross firing, cracks, carbon
tracking, plug boot damage, pinched, incorrect routing, or a resistance value
more than the specified value. |
Spark Plug Wires Resistance
3280-4921 ohm/meter(1000-1500 ohms/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 malfunctioning.
|
| - | Malfunctioning ignition control module |
| - | Ignition system wiring - Loose ignition module feed or ground
connection, or damaged system wiring. |
| • | Remove spark plugs and inspect for the following conditions: |
| - | Burned or damaged electrodes |
| • | If spark plugs are gas or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
|
Engine Mechanical
| Test 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 Tests
|
| • | Inspect the intake and exhaust manifolds for casting flash. |
| • | Test TCC operation. Refer to A Diagnostic Starting Point in 4L60E
Automatic Transmission. |
| • | Test the exhaust system for a possible restriction. |
| - | Inspect exhaust system for damaged or collapsed pipes. |
| - | Inspect mufflers for heat distress or possible internal failure. |
|
