Inspection/Tests
| Action
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DEFINITION: Engine power variation under steady throttle or cruise. Feels like the vehicle speeds up and slows down with no change in the accelerator pedal position.
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Preliminary
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| • | Verify the driver understands the operation of the transmission torque converter clutch (TCC) and A/C compressor operation as explained in the owners manual. |
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Sensor/System
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Notice: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in the Preface section. | • | Inspect the heated oxygen sensors (HO2S). The HO2S should respond quickly to different throttle positions. If they do not, inspect the HO2S for silicon or other contaminates from fuel or the use of improper RTV sealant. The sensors may have a white,
powdery coating and result in a high but false signal voltage rich exhaust indication. The ECM will then reduce the amount of fuel delivered to the engine causing a severe driveability problem. |
| • | Inspect for proper operation of the throttle position (TP) sensor. Refer to
DTC P0106 . |
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Fuel System
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| • | Verify that each injector harness is connected to the correct injector or cylinder. Relocate the injector harnesses as necessary. |
| • | 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 HO2S connector |
| - | An evaporative emission (EVAP) canister purge condition |
| - | 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. |
| - | Vacuum hoses that are split, kinked, or improperly connected |
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Ignition System
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| • | In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures: |
| • | Remove spark plugs and inspect for the following: |
| - | Verify that the spark plugs are of the correct type. |
| • | Inspect for proper ignition voltage output with the
J 26792 (SA9199Z) Spark Tester. |
| • | An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gage gap tool. |
| • | Determine the cause of the fouling before replacing the spark plugs. |
| • | Inspect for damaged or misaligned spark plug boots. |
| • | Inspect the electronic ignition (EI) module for proper ground connection. |
| • | Monitor the Misfire Current Counters while driving the vehicle in the conditions that the symptom occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to
DTC P0300 . |
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Engine Mechanical
| Inspect for excessive crankshaft endplay that will cause the 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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| • | Visually and physically inspect vacuum hoses for splits, kinks, and proper connections and routing as shown on the Vehicle Emission Control Information label. |
| • | Inspect the transmission torque converter clutch (TCC) for proper operation. Refer to
Torque Converter Diagnosis for the 4T40-E/4T45-E transmission. |
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