Hesitation, Sag, Stumble

DEFINITION
Momentary lack of response as the accelerator is depressed. The problem can occur at all vehicle speeds. Usually most severe when accelerating from a stop, and may cause the engine to stall. Usually caused by a lean condition (not enough fuel).

POWERTRAIN SYSTEM
Perform Powertrain System Check, if not already completed. Chart 1 Powertrain System Check

FUEL SYSTEM
Perform Chart 6C-1 Fuel System Check looking in particular for:

^ Fuel Quality
- Alcohol Content
- Contaminants
- Water Content
- Sour Fuel
^ Low Fuel Pressure
- Fuel Pump Circuit Problem
^ Fuel Injectors
- Not Operating
- Low Flow Rate
^ Plugged or dirty Fuel Filter
^ Idle Speed Control
- Binding Idle Speed Control (ISC) Motor
- Sticking Throttle Position Switch

Chart 6C-1 Fuel System Check

IGNITION SYSTEM
Perform Chart 1 Ignition System Check, looking in particular for:

^ High Resistance, Open, Shorted, or Arcing Spark Plug Wires, crossfire between spark plug wires
^ Contaminated or Damaged Spark Plugs
^ Faulty Coil Pack or Ignition Control (IC) Module

Chart 1 Ignition System Check

EXHAUST GAS RECIRCULATION
Check EGR System. Refer to Chart 6EC-1 EGR System Check. Chart 1 Ignition System Check

MECHANICAL CAUSES
Check for the following mechanical causes:

- If "Traction Control" telltale is on when the condition occurs, Check Traction Control Operation.
- Binding or Sticking Throttle Linkage
- Intake Valve Deposits
- Valves Sticking in Guides
- Improper Camshaft Timing
- Vacuum Leaks in Intake Manifold System