Surges/Chuggles

SYMPTOM DESCRIPTION:

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


POSSIBLE CAUSE ACTION



Ignition System Malfunction Scope check Ignition System

Check IGNITION COIL for proper output voltage.

Check SPARK PLUGS for proper spark duration. Remove spark plugs, check for fuel fouled plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits. Replace as necessary.

Check SECONDARY CIRCUIT for abnormal firing Kv, crossfire between spark plugs (distributor cap, spark plug wires), and proper plug wire routing.

Check IGNITION TIMING for excessive spark advance or retard.



Engine Mechanical Malfunction Check COMPRESSION Perform a compression check, and cylinder leakage test, look for sticking or leaking valves.

Check for VACUUM LEAKS inspect Intake manifold, gasket(s), and hoses.



Emissions Component Malfunction Check EGR valve for premature opening.

Check EGR Transducer for proper operation.

Check Evaporative control system.



Fuel System Malfunction Check for incorrect Air-Fuel mixture, O2 Sensor, perform injector balance test, inspect regulator operation (check vacuum line and return hose), check fuel pressure.

Check Throttle Position Sensor for proper operation.

Check fuel quality.



Charging System Malfunction Check battery voltage.

Check Alternator voltage output.