Lack of Power, Sluggish or Spongy
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 Checks
|
| • | Check items which can cause an engine to run rich (long term
fuel trim is significantly in the negative range). Refer to Diagnostic Aids
for DTC P0172. |
| • | Check items that can 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
. |
| • | Check for a restricted air intake system. |
|
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 J 26792
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 J 26792
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 Resistance
5000 - 7000 ohms (5K - 7K 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
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 components will arc to ground
when a secondary component is faulty.
|
| - | Ignition System Wiring -- Loose ignition module feed or
ground connection, or damaged system wiring. |
| • | Remove spark plugs and check for the following: |
| - | 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
|
| • | Excessive oil in combustion chamber--Leaking valve seals.
Refer to Base Engine Misfire Diagnosis
. |
| • | Low cylinder compression. Refer to Engine Compression Test
. |
| • | For incorrect basic engine parts. Inspect the following: |
| • | Refer to Base Engine Misfire Diagnosis
. |
|
Additional Checks
| Check exhaust system for possible restrictions. Check for the following:
| • | Inspect exhaust system for damaged or collapsed pipes. |
| • | Inspect mufflers for heat distress or possible internal failure. |
|
