G424F(FE) Service Manual
234
Chapter 8. Basic Troubleshooting
Surges and/or Stumbles
Engine power varies under steady throttle or cruise. Feels like the vehicle speeds up and slows down with no
change in the acceleration pedal.
Preliminary Checks
Perform the visual checks as described at start of “ Basic Troubleshooting” chapter.
Be sure driver understands vehicle operation as explained in the operator manual.
PROBABLE CAUSE
CORRECTIVE ACTION
Oxygen sensor
malfunction
The fuel management should maintain a stoichiometric air-fuel ratio under all
steady state operating conditions following engine warmup. Failure of the Pre-
catalyst O2 sensor should cause an O2 sensor fault that can be diagnosed with
the MIL lamp or Service Tool.
Fuel system malfunction
NOTE: To determine if the condition is caused by a rich or lean system, the
vehicle should be driven at the speed of the complaint. Monitoring pre-catalyst
O2 adapts*, dither valve duty cycle, or mechanical injector pulse width will help
identify problem.
Check fuel supply while condition exists.
Check in-line fuel filter. Replace if dirty or plugged.
Check fuel pressure.
Ignition system
malfunction
Check for proper ignition voltage output using spark tester.
Check spark plugs.
•
Remove spark plugs, check for wet plugs, cracks, wear, improper gap, burned
electrodes, or heavy deposits.
•
Repair or replace as necessary.
•
Check condition of distributor cap, rotor and spark plug wires (where
applicable).
Check ignition timing. Refer to application manual for specs.
Component malfunction
Check vacuum lines for kinks or leaks.
Check alternator output voltage. Repair if less than 9 or more than 16 volts.
Exhaust backpressure
Check condition of exhaust system.
Check backpressure before catalyst. It should be less than 3.5 psig (24.13 kPa).
(*) Refer to Table 1 for description of gaseous and liquid O2 adapts.
Related MIL Faults:
Pre-catalyst O2 sensor errors / O2 control errors
Dither valve DC faults / EST faults / ETC faults
Содержание G20P-5
Страница 2: ......
Страница 4: ......
Страница 31: ...G424F FE Service Manual Chapter 2 Recommended Maintenance 29 ...
Страница 36: ...G424F FE Service Manual Chapter 3 Engine Mechanical System 34 MAIN BEARINGS 0 50 UNDERSIZE ...
Страница 86: ...G424F FE Service Manual Chapter 3 Engine Mechanical System 84 ...
Страница 113: ...G424F FE Service Manual Chapter 4 Engine Electrical System 111 2 Alternator and outer terminal connection inspection ...
Страница 153: ...G424F FE Service Manual Chapter 5 Engine Management System EMS 151 Figure 22 SECM Wiring Diagram for G424FE LP System ...
Страница 162: ...G424F FE Service Manual Chapter 5 Engine Management System EMS 160 SECM Wiring Diagrams for G424F LP Engine ...
Страница 230: ...G424F FE Service Manual 228 Chapter 8 Basic Troubleshooting Irregular Idling Or Engine Is Suddenly Stopped ...
Страница 231: ...G424F FE Service Manual 229 Chapter 8 Basic Troubleshooting Engine Hesitation Or Insuffient Accelelation ...
Страница 232: ...G424F FE Service Manual 230 Chapter 8 Basic Troubleshooting ...
Страница 234: ...G424F FE Service Manual 232 Chapter 8 Basic Troubleshooting ...