Hesitation/Sag/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. Check the following systems and components.



COMPUTER INPUTS/OUTPUTS
^ THROTTLE SWITCH: Check for binding or sticking.
^ AIR FLOW METER: Check for sticking flap.
^ DME CONTROL UNIT: Check for correct DME control unit and PROM I.D.
^ ENGINE SPEED/REFERENCE SENSOR: Damaged or incorrectly positioned sensor, broken or missing teeth on the reference wheel.
^ OXYGEN SENSOR: Damaged or defective oxygen sensor.



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



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



EMISSIONS
^ EVAPORATIVE SYSTEM: Cannister purge system operation.
NOTE: Refer to EMISSION CONTROLS for testing procedures.



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