Diagnosis Information & Procedures: Surges/Chuggles

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

Surges/Chuggles

Inspections	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 Inspections	Refer to Symptoms - Engine Controls . Be sure that the driver understands the torque converter clutch operation. Be sure that the driver understands the A/C compressor operation. Ensure that the transmission fluid is at the proper level.
Sensor/System	Display the scan tool parameters for the various engine controls sensors. Inspect for any abnormal readings.
Fuel System	Inspect 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 condition. Lean - The long term fuel trim will be more than 150. Rich - The long term fuel trim will be less than 115. Test the fuel pressure while the condition exists. Refer to Fuel System Diagnosis . Inspect the in-line fuel filter for a restrictions.
Ignition System	Inspect the spark plugs. Remove the plugs and inspect for the following conditions: Wetness Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to Spark Plug Inspection .
Additional	Inspect the control module grounds for being clean, tight, and in their proper locations. Refer to Power and Grounding Component Views in Wiring Systems. Test the generator output voltage. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical. Inspect the vacuum hoses for kinks or leaks. Inspect the torque converter clutch (TCC) operation. Refer to Torque Converter Diagnosis Procedure in Automatic Transmission. Inspect the exhaust system for a possible restriction. Refer to Restricted Exhaust in Engine Exhaust.