Lack of Power, Sluggish, or Spongy
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. Refer
to the Diagnostic Aids for DTC P0172. |
| • | Inspect any items which may cause an engine to run lean. Refer
to the Diagnostic Aids for DTC P0171. |
|
Sensor/System
|
| • | If the knock retard is more than 10-12 degrees,
disconnect the KS 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, replace the PCM. Refer to
Powertrain Control Module Replacement/Programming
. |
| • | Inspect the air intake ducts for collapsing, damaged areas, looseness,
improper installation, or leaking, especially between the MAF sensor and
the throttle body. |
|
Ignition System
|
| • | Inspect for the 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 crisp blue 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: |
| - | Check the coils for cracks, carbon tracking or arcing, or a resistance
value outside the specified range. |
Coil Resistance
5000-8000 ohms | - | Check the spark plug wires for signs of arcing, cross firing,
cracks, carbon tracking, plug boot damage, pinching, improper routing, or
a resistance value outside the specified range. |
Spark Plug Wire Resistance
1 968 ohms per meter (600 ohms per foot).
| | Important: : Spraying the secondary ignition wires with a light mist of water may
help locate an intermittent problem. The ignition voltage will arc to ground
when a secondary component is faulty.
|
| - | Check for a faulty ignition module. |
| - | Check the ignition system wiring for a loose ignition module
feed or ground connection, or damaged system wiring. |
| • | Remove the spark plugs and inspect for the following conditions: |
| - | Burned or damaged electrodes |
| - | Improper heat range or reach |
| • | If the spark plugs are gas or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. Refer to
Spark Plug Visual Diagnosis
in Engine Electrical. |
|
Engine Mechanical
| Check for the following conditions:
| • | Any excessive oil in the combustion chambers and leaking valve
seals. Refer to
Oil Consumption Diagnosis
in Engine Mechanical. |
| • | Inspect the following components for incorrect basic engine parts: |
| - | The camshaft and the valve train components |
|
Additional
| Inspect the exhaust system for restrictions:
| • | Inspect the exhaust system for damaged or collapsed pipes.
|
| • | Inspect the mufflers for heat distress or internal failure.
|
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