Inspection/Test
| 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
|
| • | 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°, disconnect the
knock sensor, 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/Programming
. |
| • | Inspect MAF sensor and related wiring. |
| • | Inspect the air intake ducts for being collapsed, damaged areas,
looseness, improper installation, or leaking especially between the 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
spark tester; 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
spark tester; a spark should be observed. |
| 5. | Repeat the above steps for each coil. |
| • | If spark is not present at the coils, inspect for the following
conditions: |
| - | Coils--Cracks, carbon tracking/arcing, or a resistance value
outside the specified range. |
Coil Resistance
5000-8000ohms (5K-8Kohms) | - | 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
600ohms per foot (1 968ohms per meter).
| | 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.
|
| - | 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. |
|
Engine Mechanical
| Inspect for the following conditions:
| • | Incorrect basic engine parts--Inspect the following components: |
| - | Camshaft and valve train components |
|
Additional
| Inspect the exhaust system for possible restrictions. Inspect
for the following:
| • | Inspect exhaust system for damaged or collapsed pipes. |
| • | Inspect mufflers for heat distress or possible internal failure. |
|
