Hesitation/Sag/Stumble

Symptom: Momentary lack of response as the accelerator is pushed down. Can occur at all car speeds. Usually most severe when trying to drive away from a stop. May cause the engine to stall, if severe enough.

NOTE: This symptom may be cause by an accumulation of intake valve deposits and/or clogged fuel injectors. Refer to the TSB for further information.

POSSIBLE CAUSES
Vacuum Hoses
- Vacuum hoses split, kinked, improperly connected, as shown on vehicle emission control label vacuum diagram.

Engine Mechanical
- Air leaks at common chamber and intake manifold gaskets

Ignition System
- Ignition wires cracked, burned spots or burned ends, hardening, correct firing order, and proper resistance.
- Wiring harness bare spots, pinches, cuts or corroded connections.
- Ignition timing.
- Open ignition system ground.

Fuel System
- Fuel pressure.
- Water contaminated fuel.
- Throttle Position Sensor (TPS) binding or sticking.
- Air flow sensor.
- Clogged fuel injectors.

Emission Systems
- Canister purge system operation.
- EGR valve operation.

Starting And Charging System
- Alternator output voltage.