Service Manual — page 128 of 715

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3-38 FUEL SYSTEM (DFI)
DFI System Troubleshooting Guide

       Symptoms or Possible Causes                              Actions (chapter)
Other:
Intermittent any DFI fault and its recovery      Check that DFI connectors are clean and tight,
                                                 and examine leads for signs of burning or fraying
                                                 (see chapter 3).

Poor Running or No Power at High Speed
        Symptoms or Possible Causes                             Actions (chapter)
Firing incorrect:
Stick coil shorted or not in good contact        Inspect or Reinstall (see chapter 16).
Stick coil trouble                               Inspect (see chapter 16).
Spark plug dirty, broken or gap maladjusted      Inspect and replace (see chapter 16).
Spark plug incorrect                             Replace it with the correct plug (see chapter 2).
ECU trouble                                      Inspect (see chapter 3).
Fuel/air mixture incorrect:
Air cleaner clogged, poorly sealed, or missing   Clean element or inspect sealing (see chapter 2).
Air duct loose                                   Reinstall (see chapter 3).
Throttle body assy holder loose                  Reinstall (see chapter 3).
Throttle body assy dust seal damage              Replace (see chapter 3).
Water or foreign matter in fuel                  Change fuel. Inspect and clean fuel system (see
                                                 chapter 3).
Fuel injector O-ring damage                      Replace (see chapter 3).
Fuel injector clogged                            Inspect and repair (see chapter 3).
Fuel line clogged                                Inspect and repair (see chapter 3).
Fuel pump operates intermittently and often DFI Fuel pump bearings may wear. Replace the fuel
fuse blows.                                      pump (see chapter 3).
Fuel pump trouble                                Inspect (see chapter 3).
Intake air pressure sensor #1 trouble            Inspect (see chapter 3).
Intake air pressure sensor #2 trouble            Inspect (see chapter 3).
Cracked or obstructed intake air pressure sensor Inspect and repair or replace (see chapter 3).
#1 and #2 vacuum hoses
Water temperature sensor trouble                 Inspect (see chapter 3).
Intake air temperature sensor trouble            Inspect (see chapter 3).
Main throttle sensor trouble                     Inspect (see chapter 3).
Subthrottle sensor trouble                       Inspect (see chapter 3).
Subthrottle valve actuator trouble               Inspect (see chapter 3).
Knocking:
Fuel poor quality or incorrect                   Fuel change (Use the gasoline recommended in
                                                 the Owner’s Manual).
Spark plug incorrect                             Replace it with the correct plug (see chapter 2).
Stick coil trouble                               Inspect (see chapter 16).
ECU trouble                                      Inspect (see chapter 3).
Engine vacuum not synchronizing                  Inspect and adjust (see chapter 2).
Intake air pressure sensor #1 trouble            Inspect (see chapter 3).
Intake air pressure sensor #2 trouble            Inspect (see chapter 3).
Water temperature sensor trouble                 Inspect (see chapter 3).