Surges at Steady Speed
DefinitionEngine power variation under steady throttle or cruise. Feels like the car speeds up and slows down with no change in accelerator pedal.
POSSIBLE CAUSE ACTION
Lean operating condition NOTE To determine if the condition is caused by
a lean or rich system, drive vehicle at
speed of complaint and monitor fuel trim.
Check Air/fuel ratio (O2 Sensor Voltage)
Perform Oxygen Sensor Test
Insufficient fuel delivery Check - Fuel pressure/ regulator.
Testing and Inspection
- Fuel filter/ hose or line restriction
Repair/Replace As required
Leaking/Inoperative fuel injector(s) Check Injector(s).
Perform: - Injector driver circuit test. - Injector service (cleaning)
Contaminated fuel Check Water or excessive alcohol in fuel. Alcohol/Contaminants-In-Fuel Testing Procedure
Replace Drain fuel tank and add clean fuel
Vacuum leak Check - Intake manifold surface and gasket
- Throttle body base surface and gasket