Inspection/Tests
| Action
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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 Inspections
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Fuel System
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| • | Inspect both injector fuses for being open. An open injector fuse causes 4 ignition coils and 4 injectors not to operate. Replace the fuse. Inspect the ignition coil circuits and the injector circuits for an intermittent short to ground. |
| • | Inspect for the following that may cause the engine to run rich: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. | - | Water intrusion in the heated oxygen sensor (HO2S) connector |
| - | Engine oil contaminated by fuel |
| - | An evaporative emission (EVAP) canister purge condition |
| - | An inaccurate mass air flow (MAF) sensor |
| - | Vacuum hoses that are split, kinked, or improperly connected |
| - | An air intake duct that is collapsed or restricted |
| • | Inspect for the following conditions that may cause the engine to run lean: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. | - | Water intrusion in the HO2S connector |
| - | An exhaust leak between the HO2S and the engine--Refer to
Exhaust Leakage
. |
| - | An inaccurate MAF sensor |
| - | Vacuum hoses that are split, kinked, or improperly connected |
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Sensor/System
| Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to
Knock Sensor (KS) System Description
.
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Ignition System
|
| • | Verify that both fuel injector fuses are not open. An open fuel injector fuse causes 4 ignition coils and 4 fuel injectors not to operate. Inspect the ignition coil circuit and the injector circuits for an intermittent short to ground.
Refer to
Circuit Testing
in Wiring Systems. Replace the fuse. |
| • | Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as water is applied. |
| • | Inspect for proper ignition voltage output with the
J 26792
Spark Tester. |
| • | Remove the spark plugs and inspect for the following: |
| • | An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Refer to
Spark Plug Replacement
. |
| • | Determine the cause of the fouling before replacing the spark plugs. |
| • | Monitor the Misfire Current Counters while driving the vehicle within the conditions that the misfire occurred. If a misfiring cylinder can be located with a misfire, use the DTC P0300 table for diagnosis. Refer to
DTC P0300-P0308
. |
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Engine Mechanical
|
| • | Verify that the engine coolant temperature (ECT) is not above 130°C (266°F). This condition causes the ECM to operate in Engine Coolant Over Temperature-Fuel Disabled Mode. While in Engine Coolant Over Temperature-Fuel Disabled Mode, the
ECM will disable the fuel injectors to 4 cylinders at a time to keep engine temperatures from reaching damaging levels. The driver may perceive the Engine Coolant Over Temperature-Fuel Disabled Mode as a lack of power, miss, or rough idle. If the vehicle
operates in Engine Coolant Over Temperature-Fuel Disabled Mode, refer to
Engine Overheating
for diagnosis. |
| • | Inspect for incorrect basic engine parts, including the following: |
| • | Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to
Crankshaft and Bearing Cleaning and Inspection
. This could result in any of the following conditions: |
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Additional Inspections
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| • | Inspect the exhaust system for possible restrictions. Perform the following: |
| - | Inspect the exhaust system for damaged or collapsed pipes. |
| - | Inspect the mufflers for heat distress or internal failure. |
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