Hesitation/Stumble

SYMPTOM DESCRIPTION:

Momentary lack of response when the accelerator is pushed down. Can occur at any speed. Usually most severe from a stop or initial take off. Engine may stall if condition is bad enough.




SYSTEM OR COMPONENT TO CHECK ACTION

COMPUTER INPUTS/OUTPUTS CHECK: ^ THROTTLE SWITCH: Check for binding
or sticking.
^ AIR FLOW METER: Check for sticking flap.
^ ELECTRONIC CONTROL UNIT: Check for correct
electronic control unit.
^ ENGINE SPEED/REFERENCE SENSOR: Damaged
or incorrectly positioned sensor.
^ OXYGEN SENSOR: Damaged or defective
oxygen sensor.
^ TURBOCHARGER SYSTEM




FUEL CHECK: ^ FUEL PRESSURE: Check for insufficient fuel
pressure or volume.
^ FUEL INJECTORS: Clogged or stuck injector,
poor spray pattern
^ WATER CONTAMINATED FUEL:





IGNITION CHECK: ^ Faulty spark plug wires.
^ Fouled spark plugs.





EMISSIONS CHECK: ^ EVAPORATIVE SYSTEM: Cannister purge system
operation.

NOTE: Refer to EMISSION CONTROLS for testing
procedures.





ENGINE CHECK: ^ CHARGING VOLTAGE: Test battery condition,
and alternator output.