Surges at Steady Speed

Definition: Engine 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 ^ Check computer controls. To determine if the condition is caused by a lean or rich system, drive vehicle at speed of complaint and monitor fuel trim.



Insufficient fuel delivery ^ Check fuel pressure. Testing and Inspection
^ Check fuel pressure regulator.
^ Check for restricted fuel filter and replace if needed.



Contaminated fuel ^ Check for water or excessive alcohol in fuel. Alcohol/Contaminants-In-Fuel Testing Procedure
^ Drain fuel tank and add clean fuel. Fuel Tank Draining



Vacuum leak ^ Check intake manifold, throttle body base and gasket.