Lack Of Power, Sluggishness, Or Sponginess
Checks
| Action
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DEFINITION: The engine delivers less than expected power. There is little or no increase in speed when partially applying the accelerator pedal.
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Preliminary Checks
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• | Compare the customers vehicle with a similar unit in order to determine if the customer has an actual condition. |
• | Remove the air filter element and check for dirt or restrictions. |
• | Check the air inlet duct for any blockage or restrictions. |
• | Check the transmission shift pattern and down-shift operation. |
|
Sensor/System
| Inspect the throttle actuator control (TAC) system for correct operation. Refer to
Throttle Actuator Control (TAC) System Description
.
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Fuel System Checks
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• | Test for a restricted fuel filter or incorrect fuel pressure. |
• | Test the fuel injectors. Perform the following procedures: |
|
Ignition System Checks
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• | Test for the proper ignition voltage output with a
J 26792
Spark Tester. |
• | Inspect the spark plugs for correct operation and good ignition system performance. Refer to
Spark Plug Inspection
. |
• | Inspect the knock sensor (KS) and the sensor circuit shielding. A faulty knock sensor or signal interference could cause excessive retard of the ignition timing advance. Observe the spark parameter on a scan tool and compare with a known good vehicle. |
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Exhaust System Checks
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• | Inspect the exhaust system for damaged or collapsed pipes. Inspect the muffler for heat distress or a possible internal failure. |
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Engine Mechanical Check
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• | Check for any of the following engine mechanical problems: |
- | An incorrect valve timing |
- | An incorrect or worn camshaft |
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Additional Checks
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• | If the loss of power is above 4,200 RPM, inspect for the correct operation of the rocker arm oil control system. Refer to
DTC P2646
. |
• | Check the powertrain control module (PCM) grounds for being clean, tight, and in the correct locations. Refer to
Engine Controls Schematics
. |
• | Check the generator output voltage. |
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