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
|
| • | Refer to Important Preliminary Checks
. |
| • | Be sure the driver understands the Torque Converter Clutch operation. |
| • | Be sure the driver understands the A/C Compressor operation. |
| • | Use the scan tool to make sure 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. Refer to DTC P0500 Vehicle Speed Sensor (VSS) Circuit
Diagnostic Aids. |
|
Sensor Check
| Check the (Heated) Oxygen
Sensor (HO2S) performance. Refer to the following items:
| • | DTC P0131 HO2S Circuit Low Voltage Sensor 1 |
| • | DTC P0132 HO2S Circuit High Voltage Sensor 1 |
| • | DTC P0133 HO2S Slow Response Sensor 1 |
| • | DTC P0134 HO2S Circuit Insufficient Activity Sensor 1 |
| • | DTC P0137 HO2S Circuit Low Voltage Sensor 2 |
| • | DTC P0138 HO2S Circuit High Voltage Sensor 2 |
| • | DTC P0140 HO2S Circuit Insufficient Activity Sensor 2 |
| • | DTC P0141 HO2S Heater Performance Sensor 2 |
|
Fuel System
Checks
|
| • | Check for a Rich or Lean symptom that causes the condition. Drive
the vehicle at the speed of the complaint. Monitoring the Fuel Trim will help
identify the problem. |
| • | Lean - The Long Term Fuel Trim will be greater than 150. Refer
to DTC P0132 HO2S Circuit High Voltage Sensor 1
Diagnostic Aids. Refer to DTC P0138 HO2S Circuit High Voltage Sensor 2
Diagnostic Aids. |
| • | Rich - The Long Term Fuel Trim will be less than 115. Refer to DTC P0131 HO2S Circuit Low Voltage Sensor 1
Diagnostic Aids. Refer to DTC P0137 HO2S Circuit Low Voltage Sensor 2
Diagnostic Aids. |
| • | Check the fuel pressure while the condition exists. Refer to Fuel System Pressure Test
. |
| • | Check the in-line fuel filter for a restrictions. Refer to Fuel System Pressure Test
. |
|
Ignition
System Checks
|
| • | Check for the proper ignition output voltage using the spark tester J 26792
or the equivalent. Refer
to Enhanced Ignition System Diagnosis (System Check)
. |
| • | Check the spark plugs. Remove the plugs, and inspect them for
the following conditions: |
| • | Check the Crankshaft Position (CKP) sensor. |
|
Additional
Checks
|
| • | Check the Control Module grounds for being clean, tight, and in
their proper locations. |
| • | Check the generator output voltage. |
| • | Check the vacuum hoses for kinks or leaks. Refer to the Vehicle
Emission Control Information label. |
| • | Check for an intermittent EGR problem. Refer to EGR System Diagnosis (Overview)
. |
| • | Check for Torque Converter Clutch (TCC) operation. Refer to Transmission. |
|
