Surges and/or Chuggles Symptom
Checks
| Action
|
DEFINITION: The engine has a power variation under a steady throttle or cruise.
There is a feeling as if the vehicle speeds up and slows down with no change in the
accelerator pedal.
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Preliminary Checks
|
• | Be sure the driver understands the A/C compressor operation. |
• | Use a scan tool to make sure the reading of the vehicle speed sensor (VSS)
matches the reading of the instrument panel speedometer. Transmission performance
can be affected by incorrect VSS readings. If accuracy of the VSS is a concern, refer
to
Speedometer and/or Odometer Inaccurate or Inoperative
in Instrument Panel, Gages, and Console. |
|
Sensor Checks
|
• | Check the heated oxygen sensors (HO2S) 1 and HO2S 2 performance.
Refer to the Diagnostic Aids for
DTC P0130
. |
• | Inspect the mass air flow (MAF) sensor operation. Run the engine to normal
operating temperature. Turn OFF all accessories and observe the MAF sensor at idle
with a scan tool. If the MAF sensor reading is more than 3.5 g/s refer to
DTC P0101
. |
• | Check for correct operation of the engine coolant temperature (ECT) sensor.
A fixed or inaccurate ECT sensor reading can cause the engine to surge, especially
at low speeds and at stops. |
|
Fuel System Checks
|
• | Determine if a rich or lean system can cause the condition. Drive the
vehicle at the speed of the complaint. Monitoring the Fuel Trim may help identify
the problem. |
- | Lean--The Long Term Fuel Trim will be more than 20 percent.
Refer to Diagnostic Aids in
DTC P0171
. |
- | Rich--The Long Term Fuel Trim will be less than -20 percent.
Refer to Diagnostic Aids in
DTC P0172
. |
• | Check the fuel injectors. Perform the following procedures: |
|
Ignition System Checks
|
• | Check for the proper secondary voltage output with a J 26792
Spark Tester. |
• | Inspect the spark plugs for correct operation and good ignition system
performance. Refer to
Spark Plug Inspection
. |
|
Additional Checks
|
• | Check the powertrain control module (PCM) grounds for being clean, tight,
and in the proper locations. Refer to
Engine Controls Schematics
. |
• | Check the generator for the correct output voltage. |
• | Check the vacuum lines and hoses for leaks or incorrect routing. |
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