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
|
| • | 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
powertrain control module (PCM). Refer to
Powertrain Control Module Replacement
. |
| • | Inspect the exhaust gas recirculation (EGR) system for proper operation,
if applicable. |
| • | Inspect the air intake ducts for being collapsed, damaged areas, looseness,
improper installation, or leaking 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. |
| • | 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
5000-8000 ohms (5K-8K ohms) | - | 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
9 686 ohms
per meter (3,000 ohms per foot)
| | 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. Refer to
Spark Plug Inspection
. |
|
Engine Mechanical
|
| • | For incorrect basic engine parts--Inspect the following conditions: |
| - | 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. |
| • | For possible plugged catalytic converter |
| • | Test for proper torque converter clutch (TCC) operation. |
|
