Inspection/Tests
| Action
|
DEFINITION: Engine
delivers less than expected power. Little or no increase in speed when
the accelerator pedal is pushed down part way.
|
Preliminary
|
|
Fuel
System Test
|
| • | Test for faulty fuel injectors. Refer to the following test procedures: |
| • | Inspect any items which may cause an engine to run rich, long
term fuel trim is significantly in the negative range. Refer to Diagnostic
Aids for
DTC P0172
. |
| • | Inspect any items which may cause an engine to run lean, long
term fuel trim is significantly in the positive range. Refer to Diagnostic
Aids for
DTC P0171
. |
|
Sensor/System
|
| • | If knock retard is above 10-12 degrees, disconnect
the KS, and ground the sensor harness connector. Monitor knock retard
on the scan tool. There should be no knock retard present, if knock
retard is still present, replace the PCM. Refer to
Powertrain Control Module Replacement
. |
| • | Inspect the air intake ducts for the following conditions: |
| - | Leaking conditions especially between the mass air flow (MAF)
sensor and the throttle body |
|
Ignition
System
|
| • | Inspect for proper ignition voltage output using the following
steps: |
| 1. | Attach the J 26792
spark tester to engine ground. |
| 2. | Connect the spark plug end of the spark plug wire to the J 26792
. Leave the other end of
the spark plug wire connected to the coil being tested. |
| 3. | Connect the spark plug end of the companion spark plug wire to
ground. The companion spark plug wire is the wire attached to the corresponding
coil tower. |
| 4. | Crank the engine while observing the J 26792
. A spark should be observed. |
| 5. | Repeat the above steps for each coil. |
| | Important: Spraying the secondary ignition wires with a light mist of water may
help locate an intermittent problem. Ignition voltage will arc to ground when
a secondary component is faulty.
|
| • | If spark is not present at the coils, inspect the following components
for the specified conditions: |
| - | Coils--Cracks, carbon tracking and/or arcing, or a resistance
value outside the specified range |
Coil Resistance
5000-8000 ohms (5K-8K ohms)
Spark Plug Wire Resistance
9868 ohms per meter (3000 ohms per foot)
| • | A resistance value outside the specified range |
| - | Defective ignition 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 |
| - | 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. Refer to
Spark Plug Inspection
. |
|
Engine
Mechanical
|
| • | Inspect the following components for incorrect basic engine parts: |
| - | Camshaft and valve train components |
|
Additional
| Inspect the
exhaust system for any possible restrictions:
| • | Inspect exhaust system for damaged or collapsed pipes. |
| • | Inspect mufflers for heat distress or possible internal failure. |
| • | Test for possible plugged catalytic converter by testing the
exhaust system back pressure. |
|
