Surges/Chuggles

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

POWERTRAIN SYSTEM CHECK
Perform Chart 1 Powertrain System Check. Chart 1 Powertrain System Check

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

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

IGNITION SYSTEM CHECKS
Perform Chart C-1 Ignition Control Performance Test. C Charts

Check in particular for:

^ High resistance, open, shorted, or arcing spark plug wires, crossfire between spark plug wires
^ Contaminated or damaged spark plugs
^ Distributor grounding points clean and tight
^ Correct ignition timing
^ Faulty ignition coil or Ignition Control (IC) module
^ Distributor cap, rotor, brush and button for moisture, cracks, dust or carbon tracking
^ Worn or loose distributor shaft gear
^ Bent distributor shaft or worn distributor shaft bushing

FUEL SYSTEM CHECK
Perform Chart 6C-1 Fuel System Check. Chart 6C-1 Fuel System Check

Check in particular for:

^ Fuel Quality
- alcohol content
- contaminants
- water content
- sour fuel
^ Incorrect Fuel Pressure
^ Fuel Injectors
- leaking
- incorrect fuel pressure

Chart 6C-2 Fuel Pressure Check

TRANSMISSION TEST
Perform 4T6O-E Functional Test in Transmissions, looking in particular for:

^ Intermittent Torque Converter Clutch (TCC) operation

EXHAUST SYSTEM CHECKS
Perform Exhaust Diagnosis, looking in particular for:

^ Restricted catalytic converter or exhaust

EXHAUST GAS RECIRCULATION (EGR) SYSTEM CHECK
Perform Chart 6EC-2: EGR System Check. Chart 6EC-2 EGR System Check

EMISSION CONTROL CHECK
Perform Chart 6EC-1: EVAP System Check. Chart 6EC-1 EVAP System Check

MECHANICAL CAUSES
Check for the following mechanical causes:

^ Valves sticking in valve guides
^ Excessive oil consumption
^ Vacuum leaks in intake manifold
^ Bent push rods
^ Worn rocker arms
^ Binding or sticking throttle linkage
^ Intake valve deposits