Surges/Chuggles

DEFINITION
Engine power variation under steady throttle. Vehicle speeds up and slows down with no change to the accelerator pedal position. Usually caused by rich operation (too much fuel).

POWERTRAIN SYSTEM
Perform Powertrain System Check, if not already completed. Chart 1 Powertrain System Check

DRIVER-INDUCED CAUSES
Check for possible driver-induced causes:

^ Owner complaining about normal operation of Torque Converter Clutch (TCC) and/or A/C compressor clutch.

IGNITION SYSTEM
Perform Chart 1 Ignition System Check, looking in particular for:

^ High Resistance, Open, Shorted, or Arcing Spark Plug Wires, crossfire between spark plug wires
^ Contaminated or Damaged Spark Plugs
^ Faulty Coil Pack or Ignition Control (IC) Module

Chart 1 Ignition System Check

FUEL SYSTEM
Perform Chart 6C-1 Fuel System Check looking in particular for:

^ Fuel Quality
- Alcohol Content
- Contaminants
- Water Content
- Sour Fuel
^ Incorrect Fuel Pressure
^ Fuel Injectors
- Not Operating
- Low Flow Rate

Chart 1 Ignition System Check

TRANSMISSION CHECK
Check 4T80-E Transmission operation, looking in particular for:

^ Intermittent Torque Converter Clutch Operation.

EXHAUST DIAGNOSIS
Check exhaust system looking In particular for:

^ Restricted Catalytic Converter or Exhaust

EXHAUST GAS RECIRCULATION
Check EGR System. Refer to Chart 6EC-1 EGR System Check. Chart 6EC-1 EGR System Check

EVAPORATIVE EMISSIONS (EVAP)
Perform functional tests of EVAP components. Evaporative Emissions System

POSITIVE CRANKCASE VENTILATION SYSTEM
Perform PCV System Check. Testing and Inspection

MECHANICAL CAUSES
Check for the following mechanical causes:

- Valves Sticking in Guides
- Excessive Oil Consumption
- Camshaft Timing
- Erratic Vehicle Speed Sensor (VSS) Readings