Checks
| Action
|
DEFINITION: Engine delivers less than expected power. Little or no increase
in speed when the accelerator pedal is pushed down part way.
|
Preliminary Checks
|
|
Fuel
System
|
| • | Check the following items |
| • | Check for incorrect fuel pressure. |
| - | Check the fuel injectors. |
|
Sensor/System
|
| | If knock retard is above 10-12 degrees, disconnect the knock sensor
and ground the sensor harness connector. Monitor the knock retard on the scan
tool, there should be no knock retard present. If knock retard is still present,
the PCM is malfunctioning. Replace the PCM. Refer to
Powertrain Control Module Replacement/Programming
. |
|
Ignition
System
|
| • | Check 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 coil(s), check for the
following conditions: |
| • | Coil(s) - 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
greater than the specified value. |
Spark Plug Wires Resistance
3280-4921 ohms/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 check 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
|
| • | Excessive oil in combustion chamber-Leaking valve seals. |
| • | Low cylinder compression. |
| • | For incorrect basic engine parts. Inspect the following: |
| • | Refer to Base Engine Misfire Diagnosis
. |
|
Additional
Checks
|
| • | Check the exhaust system for a possible restriction. |
| • | Inspect the exhaust system for damaged or collapsed pipes. |
| • | Inspect the muffler for heat distress or possible internal failure. |
|
