Checks
| Action
|
DEFINITION: The engine
has a power variation under a steady throttle or cruise. The vehicle feels
as if it speeds up and slows down with no change in the accelerator pedal.
|
Preliminary Checks
|
| • | Be sure that the driver understands the Torque Converter Clutch
operation. |
| • | Be sure that the driver understands the A/C Compressor operation. |
| • | Use the scan tool to ensure that the reading of the vehicle speed
sensor (VSS) matches the vehicle speedometer. This excludes vehicles with
electronic transmissions where some variation between the VSS and the
speedometer is normal. |
|
Sensor Checks
| Verify the heated oxygen sensor (HO2S) performance by referring
to the following DTC tables in Engine Controls - 5.0, 5.7L in the
C/K Truck Service Manual:
| • | DTC P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1 |
| • | DTC P0132 HO2S Circuit High Voltage Bank 1 Sensor 1 |
| • | DTC P0133 HO2S Slow Response Bank 1 Sensor 1 |
| • | DTC P0134 Insufficient Activity Bank 1 Sensor 1 |
| • | DTC P0135 HO2S Heater Circuit Bank 1 Sensor 1 |
| • | DTC P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2 |
| • | DTC P0138 HO2S Circuit High Voltage Bank 1 Sensor 2 |
| • | DTC P0140 Insufficient Activity Bank 1 Sensor 2 |
| • | DTC P0141 HO2S Heater Circuit Bank 1 Sensor 2 |
|
Fuel System Checks
|
| • | Inspect for a rich or lean symptom that causes the condition.
Drive the vehicle at the speed of the complaint. Monitoring the oxygen sensor
will help to identify the problem. |
| • | Verify that the CNG manual fuel shut-off valve is fully open. |
| • | Inspect the high pressure regulator (HPR) fuel filter for restrictions. |
|
