Fuel and Emissions Systems

Symptom Troubleshooting Index (cont'd)

 11-173  

Symptom

Diagnostic procedure

Also check for

Idle speed fluctuates (MIL works OK, no DTCs set)
  1. Test the fuel pressure (see page 11-131).
  2. Test the injectors (see page 11-276).
  3. Troubleshoot the ALT FR signal circuit (see page 11-120).
  4. Inspect and test the PCV valve (see page 11-159).
  • Contaminated fuel

Misfire or rough running (MIL works OK, no DTCs set)
  1. Check the spark plugs (see page 4-25)
  2. Test the fuel pressure (see page 11-131).
  3. Test the injectors (see page 11-276).
  4. Troubleshoot the fuel pump circuit (see page 11-287).
  • Low compression
  • Valve Clearance
  • Contaminated fuel

Fails emission test (MIL works OK, no DTCs set)
  1. Inspect the three way catalytic converter (TWC) (see page 11-300).*3
  2. Check the spark plugs (see page 4-25).
  3. Test the fuel pressure (see page 11-131).
  4. Test the injectors (see page 11-276).
  5. Check the EVAP emission control system (see page 11-305).
  • Contaminated fuel
  • Low compression
  • Slipped/broken timing belt

Low power (MIL works OK, no DTCs set)
  1. Test the fuel pressure (see page 11-131).
  2. Check the air cleaner element (see page 11-147).
  3. Inspect/adjust the throttle cable (see page 11-149).
  4. Inspect and then test the throttle body (see page 11-299).
  5. Inspect the three way catalytic converter (TWC) (see page 11-300).*3
  6. Test the injectors (see page 11-276).
  • Contaminated fuel

Engine stalls (MIL works OK, no DTCs)
  1. Test the fuel pressure (see page 11-131).
  2. Check/adjust the idle speed (see page 11-285).
  3. Troubleshoot the brake pedal position switch signal circuit (see page 11-123).
  4. Check the spark plugs (see page 4-25).
  • Intake air leaks
  • Faulty harness and sensor connections

*3: with TWC model