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.




SYSTEM OR COMPONENT TO CHECK ACTION

COMPUTER INPUTS/OUTPUTS CHECK: - OXYGEN SENSOR (O2) -
Inspect sensor for silicon contamination
from fuel or use of improper RTV sealant.
The sensor will have a white, powdery coating,
and will result in a high but false signal
voltage (rich exhaust indication).
The Control Unit will then reduce the amount
of fuel being delivered to the engine,
causing a driveability problem.
- CONTROL UNIT -
Check grounds for being clean,
tight, and in their proper location.





FUEL
CHECK: - FUEL PRESSURE
- FUEL INJECTOR BALANCE TEST.
- IN-LINE FUEL FILTER.
NOTE: To determine if the condition is caused by a
rich or lean mixture, the vehicle should be driven at the
speed of the complaint.





IGNITION CHECK: - IGNITION COIL OUTPUT VOLTAGE
Check for spark using appropriate spark tester.
- SPARK PLUGS
Check for wet/fouled plugs, cracks, wear,
improper gap, burned electrodes or heavy deposits.
- IGNITION TIMING.




EMISSIONS CHECK: - EGR SYSTEM.
Refer to Powertrain Management/Emission Control Systems/Testing and Inspection/Procedures.






ENGINE CHECK: - VACUUM LINES
Check for kinks, leaks, and modifications.
- ALTERNATOR OUTPUT VOLTAGE
Replace or Repair if less than
9 volts or greater than 16 volts.