Lack of Power/Sluggish/Spongy/Stumble

DEFINITION
Engine delivers less than expected power. Little or no increase in speed when accelerator pedal is DEPRESSED part way.

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
- Low Octane Level
- Contaminants
^ Incorrect Fuel Pressure
^ Plugged or dirty Fuel Filter
^ Fuel Injectors
- Incorrect Flow Rate

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
^ Knock Sensor Not Operating Properly

Chart 1 Ignition System Check

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

EXHAUST DIAGNOSIS
Check exhaust system looking In particular for:

^ Restricted Catalytic Converter or Exhaust

MECHANICAL CAUSES
Check for the following mechanical causes:

- Camshaft Timing
- Low Engine Compression
- Throttle not Opening Fully
- Restricted Air Induction Flow
- Vacuum Leaks in Intake Manifold System
- Erratic Vehicle Speed Sensor (VSS) Readings
- Erratic Engine rpm Readings

DRIVER-INDUCED CAUSES
Check for possible driver-induced causes:

- Vehicle Displaying Normal Power