Lack of Power, Sluggish or Spongy
Checks
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DEFINITION: Engine delivers less than expected power. Little or no increase
in speed when the accelerator pedal is pushed down part way.
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Preliminary Checks
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• | Refer to
Symptoms
, Important Preliminary Checks Before Starting.
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• | Check PCM grounds for being clean, tight and in their proper locations.
Refer to PCM wiring diagrams in Electrical Diagnosis.
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Fuel System Checks
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Sensor/System Checks
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• | Check the EGR system for proper operation. |
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Ignition System
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• | Wetting down the secondary ignition system with water from a spray
bottle may help locate damaged or deteriorated components. Look/listen for
arcing or misfiring as water is applied. |
• | Check for proper ignition voltage output with spark tester J 26792.
Refer to Distributor Ignition System for procedure. |
• | Remove spark plugs and check for the following: |
• | An improper spark plug gap will cause a driveability problem.
Refer to spark plug gap specification is Section OB. The spark plug gapping
should be done using a wire gauge gap tool (J 41319). Refer to Spark Plug Replacement.
If spark plugs are gas or oil fouled, the
cause of the fouling must be determined before replacing the spark plugs.
Refer to
DTC P0172 Fuel Trim System Rich Bank 1
or
DTC P0175 Fuel Trim System Rich Bank 2
to determine the Rich condition or Engine Mechanical
for the oil fouling condition. |
• | Spark plugs for proper heat range. Refer to Owners Manual or Section OB.
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Engine Mechanical
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• | Excessive oil in combustion chamber-Leaking valve seals.
Refer to Engine Mechanical.
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• | Low cylinder compression. Refer to Engine Mechanical.
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• | For incorrect basic engine parts. Inspect the following: |
Refer to Engine Mechanical.
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Additional Checks
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• | 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. |
- | For possible plugged Three-Way catalytic converters by comparing
exhaust system back pressure on each side of engine. Check back pressure by
removing AIR check valves near exhaust manifolds. Refer to Restricted Exhaust
System Check and Exhaust System. |
• | Check Torque Converter Clutch (TCC) for proper operation. Refer
to Transmission Controls.
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• | TC system cable adjuster assembly. Loss of performance can result
from an improperly adjusted system which could prevent the throttle from attaining
WOT. Refer to Antilock Brake System (ABS) and Traction
Control System
. Also inspect the throttle body and accelerator
cables for binding. |
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