Hesitation, Sag, Stumble

DEFINITION: Engine power variation under steady throttle or cruise. Feels like the car speeds up and slows down with no change in the accelerator pedal.

Check if problem exists with A/C is "ON" only. Carefully perform a visual check.

CHECK:

^ Fuel pressure for varying.

^ Engine ignition timing.

^ Electronic Spark Advance (ESA) for proper operation.

^ Leaky or loose spark plug wire(s).

^ Fouled, burnt electrode, improperly gapped spark plugs.

^ Electronic fuel injection system operation.

^ Restricted fuel line, clogged, kinked, damaged, etc.

^ Ignition system operation.

^ EGR valve operation.

^ Faulty pressure sensor signal.