Hesitation, Sag, Stumble

DEFINITION
Momentary lack of response as the accelerator is pushed down. Can occur at all vehicle speeds. Usually more severe when first trying to make the vehicle move, as from a stop sign. May cause the engine to stall if severe enough.

PRELIMINARY CHECKS
Perform the careful visual and physical checks as described in Preliminary Checks. Testing and Inspection

FUEL SYSTEM
Check: Throttle Position (TP) sensor. Check TP sensor for binding or sticking Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT).

Check: Manifold Absolute Pressure (MAP) sensor response and accuracy. Refer to Chart C-1D MAP Sensor Voltage Output Check. Chart C-1D Manifold Absolute Pressure (MAP) Output Check

IGNITION SYSTEM
Check: Ignition wires for being faulty.

Check: Spark plugs for being fouled.

Check: Open ignition system ground, CKT 453.

Check: Ignition timing. Refer to underhood "Vehicle Emission Control Information" label.

ADDITIONAL CHECKS
Check: For correct PROM, refer to PROM - Programable Read Only Memory for updates. PROM - Programmable Read Only Memory

Check: Generator output voltage. Repair, if less than 9 volts or more than 16 volts.

Check: EGR valve operation refer to Chart C-7 Exhaust Gas Recirculation Check. Chart C-7 EGR System Check