Inspections
| Action
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DEFINITION: Engine power variation under steady throttle or cruise. Feels like the vehicle speeds up and slows down without a change in the accelerator pedal position.
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Preliminary
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• | Verify that the ECM and ECM bracket fasteners are at the correct torque. |
• | Ensure that the driver understands the operation of the transmission torque converter clutch (TCC) and A/C compressor operation as explained in the owner's manual. Inform the customer how the TCC and the A/C clutch operates. |
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Fuel System
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• | Verify that each injector harness is connected to the correct injector/cylinder according to the firing order. |
• | Test the items that cause an engine to run rich. For a rich condition, refer to
DTC P2178
or
DTC P2188
. |
• | Test the items that can cause an engine to run lean. For a lean condition, refer to
DTC P2177
or
DTC P2187
. |
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Ignition System
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• | Inspect for the correct installation of the ignition coil seals. Incorrect installation may allow water to enter the spark plug area. Inspect for moisture and corrosion. |
• | Remove the spark plugs and inspect for the following conditions: |
- | Refer to the following procedures: |
• | If the spark plugs are gas, coolant or oil fouled, determine the cause before replacing the spark plugs. Refer to the following procedures: |
- | For diagnosis of coolant contaminated spark plugs, refer to
Loss of Coolant
. |
• | Inspect the crankshaft position (CKP) sensor for the correct resistance. The sensor resistance may be out of range after a hot soak. Measure that the resistance remains within 700-1,200 ohms at all temperatures. |
• | Inspect the spark plug boots and terminals for burning or micro-arcing, corrosion, and damage to the insulation. |
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Additional
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• | Inspect the vacuum hoses for splits and kinks. Verify that the connections and routing are as shown on the Vehicle Emission Control Information Label. Refer to
Emission Hose Routing Diagram
. |
• | Test the transmission TCC operation. A TCC applying too soon can cause the engine to spark knock, surge or chuggle. Refer to
Torque Converter Diagnosis
. |
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