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 position.
|
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. |
| • | Ensure that the transmission fluid is at the proper level. |
|
Sensor Check
| Display the scan tool parameters for the various engine
controls sensors. Check for any abnormal readings.
|
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 more than 150. |
| • | Rich -- The long term fuel trim will be less than 115. |
| • | Check the in-line fuel filter for a restrictions. |
|
Ignition System Checks
|
| • | Check the secondary ignition system and 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 the exhaust system for a possible restriction. Refer to
Restricted Exhaust
in Engine Exhaust. |
|
