Section 1172 (Engine Controls - 6.0L - Alternative Fuels (Troubleshooting)): Troubleshooting: Surges/Chuggles

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. 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. The vehicle feels as if speeds up and slows down with no movement of the accelerator pedal.
Preliminary Checks	Refer to Important Preliminary Checks in Symptoms - Engine Controls . Ensure the vehicle operator understands the transmissions torque converter clutch (TCC) operation, if equipped. Ensure the vehicle operator understands the A/C compressor clutch operation, if equipped.
Sensor Checks	Test for proper operation of the vehicle speed sensor (VSS). Test for proper operation and performance of the oxygen sensor.
Fuel System Checks	Inspect for a lean or rich engine condition. Using a scan tool observe the oxygen sensor output while operating the vehicle under the symptom condition. Test for proper fuel system pressures. Refer to Fuel System Diagnosis . Inspect for proper operation of the CNG fuel injectors. Refer to: Fuel Injector Coil Test Fuel Injector Balance Test with Special Tool Fuel Injector Balance Test with Tech 2 Ensure that the manual shut-off valve is fully open. Inspect for restricted HPR or in-line filters. Refer to High Pressure Regulator (HPR) Filter Replacement and Fuel Filter Replacement .