Inspection/Tests
| Action
|
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.
|
Preliminary
|
• | Verify the driver understands the operation of the transmission torque converter clutch (TCC) and A/C compressor operation as explained in the owners manual. Inform the customer how the TCC and the A/C clutch operates. |
|
Sensor/System
|
• | Inspect the mass air flow (MAF) sensor for any contamination on the sensing element. |
• | Inspect the air intake ducts for being collapsed, damaged, loose, improperly installed , or leaking especially between the MAF sensor and the throttle body. |
|
Fuel System
|
• | Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary. |
• | Inspect for the following conditions that may cause the engine to run rich: |
- | Water intrusion in the heated oxygen sensor (HO2S) connector |
- | An evaporative emission (EVAP) canister purge condition |
- | Blockage on the inlet screen of the 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: |
- | Water intrusion in the HO2S connector |
- | An exhaust leak between the HO2S and the engine--Refer to
Exhaust Leakage
in Engine Exhaust. |
- | Vacuum hoses that are split, kinked, or improperly connected |
|
Ignition System
|
• | 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 you apply the water. |
• | Remove the spark plugs and inspect for the following conditions: |
• | 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, use the DTC P0300 table for diagnosis. Refer to
DTC P0300
. |
• | Inspect for loose ignition coil grounds. |
• | Inspect the ignition coils for cracks or carbon tracking. |
• | Inspect for damaged spark plug boots. |
|
Engine Mechanical
| 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
in Engine Mechanical. This could result in any of the following conditions:
|
Additional Inspections
|
• | Visually and physically inspect vacuum hoses for splits, kinks, and proper connections and routing as shown on the Vehicle Emission Control Information label. Refer to
Emission Hose Routing Diagram
. |
• | Inspect the transmission TCC operation. A TCC applying too soon can cause the engine to spark knock. |
• | Test the A/C clutch for proper operation. |
• | Inspect the exhaust system for possible restrictions. Refer to
Restricted Exhaust
in Engine Exhaust. |
|