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.




SYSTEM OR COMPONENT TO CHECK ACTION

COMPUTER INPUTS/OUTPUTS CHECK: ^ THROTTLE POSITION SENSOR (TPS):
Check for binding or sticking. Voltage should
increase at a steady rate as throttle is moved
toward Wide Open Throttle (WOT).
^ MANIFOLD ABSOLUTE PRESSURE SENSOR
(MAP): Sensor response and accuracy.
^ PROM/MEM-CAL updates. Refer to
COMPUTERIZED ENGINE CONTROLS/PROM I.D.




FUEL CHECK: ^ FUEL PRESSURE: use CHART A-6 in
DIAGNOSTIC CHARTS/A-CHARTS
^ WATER CONTAMINATED FUEL





IGNITION CHECK: ^ Spark plug wires for being faulty.
^ Spark plugs for being fouled.
^ Open ignition system ground, CKT 453.
^ Ignition timing.





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





ENGINE CHECK: ^ Generator output voltage. Repair, if less
than 9 or more than 16 volts.