Hesitation, Sag or Stumble

*** UPDATED BY TSB # 9111003, DATED FEBRUARY 1991
This symptom may be cause by an accumulation of intake valve deposits and/or clogged fuel injectors. Refer to the TSB for further information.


DEFINITION
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.


CHECK:
- Vacuum hoses for splits, kinks, and proper connections, as shown on vehicle emission control label vacuum diagram.
- Air leaks at common chamber and intake manifold gaskets.
- Ignition wires for cracks, burned spots or burned ends, hardening, correct firing order, and proper resistance.
- Wiring harness for bare spots, pinches, cuts or corroded connections.
- Fuel pressure.
- Water contaminated fuel.
- TPS for binding or sticking.
- Ignition timing. See Vehicle Emission Control Information label.
- Air flow sensor.
- Alternator output Voltage.
- For open ignition system ground.
- Canister purge system for proper operation.
- EGR valve operation.
- Clogged fuel injectors.