Section 1851 (Engine Controls And Fuel - 3.5L (L66) - Troubleshooting & Diagnosis): Surges/Chuggles

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

Surges/Chuggles

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.
Preliminary Checks	Refer to Diagnostic System Check - Vehicle . Refer to Symptoms - Engine Controls . Verify the driver understands the A/C compressor operation. Use a scan tool to ensure 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 .
Sensor Checks	Test for correct operation of the engine coolant temperature (ECT) sensor. A fixed or inaccurate ECT sensor input can cause the engine to surge. Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor . Test for the correct operation of the manifold absolute pressure (MAP) sensor. A fixed or inaccurate MAP sensor input can cause the engine to surge. Observe the MAP sensor voltage parameter with a scan tool. Compare the MAP sensor voltage to that of another vehicle, with the ignition ON and the engine OFF.
Fuel System Checks	Determine if a rich or lean system can cause the condition. Drive the vehicle at the speed of the concern. Monitoring the Fuel Trim may help identify the problem. Lean-The long term fuel trim will be more than 17 percent. Refer to DTC P0171 or P0174 . Rich-The long term fuel trim will be more than -15 percent. Refer to DTC P0172 or P0175 . Test the fuel injectors. Perform the following procedures: The Fuel Injector Coil Test-Refer to Fuel Injector Solenoid Coil Test . The Fuel Injector Balance Test-Refer to Fuel Injector Balance Test with Tech 2 . Test the fuel pressure while the condition exists. Refer to Fuel System Diagnosis .
Ignition System Checks	Test for the correct 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	Inspect the powertrain control module (PCM) grounds for being clean, tight, and in the proper locations. Refer to Engine Controls Schematics . Inspect the positive crankcase ventilation (PCV) valve for correct operation and the correct part. Refer to Crankcase Ventilation System Inspection/Diagnosis . Test the generator for the correct output voltage. Inspect the vacuum lines and hoses for leaks or incorrect routing. Refer to Emission Hose Routing Diagram . Inspect for the correct operation and the correct shifting of the automatic transmission. Inspect for correct operation and engagement of the torque converter clutch (TCC). Refer to Symptoms - Automatic Transmission .