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Engine Controls - Trouble Shooting - No Codes: Other Subaru Forester SG

Testing & Diagnostics ~706 words

ENGINE STALLS DURING IDLE

  1. Check Idle Air Control (IAC) solenoid valve.
  2. Check Intake Manifold Pressure (IMP) sensor.
  3. Check Intake Air Temperature (IAT) sensor.
  4. Check intake air temperature and pressure sensor.
  5. Check ignition parts; ignitor, ignition coil and spark plugs.
  6. Check Engine Coolant Temperature (ECT) sensor, if symptom occurs only in cold temperatures.
  7. Check Crankshaft Position (CKP) sensor, ensure component is securely installed.
  8. Check Camshaft Position (CMP) sensor, ensure component is securely installed.
  9. Check fuel injection components; fuel injectors, fuel pressure regulator and fuel filter.
  10. Check EGR valve (Outback 3.0L).

ROUGH IDLE

  1. Check Idle Air Control (IAC) solenoid valve.
  2. Check Intake Manifold Pressure (IMP) sensor.
  3. Check Intake Air Temperature (IAT) sensor.
  4. Check intake air temperature and pressure sensor.
  5. Check Engine Coolant Temperature (ECT) sensor, if symptom occurs only in cold temperatures.
  6. Check ignition parts; ignitor, ignition coil and spark plugs.
  7. Check air intake system for air leak(s).
  8. Check fuel injection components; fuel injectors, fuel pressure regulator and fuel filter.
  9. Check Throttle Position (TP) sensor.
  10. Check Crankshaft Position (CKP) sensor, ensure component is securely installed.
  11. Check Camshaft Position (CMP) sensor, ensure component is securely installed.
  12. Check Heated Oxygen Sensor (HO2S).
  13. Check fuel pump and fuel pump relay.
  14. Check EGR valve (Outback 3.0L).

ENGINE DOES NOT RETURN TO IDLE

  1. Check Idle Air Control Solenoid (IACS) valve.
  2. Check Engine Coolant Temperature (ECT) sensor.
  3. Check accelerator cable, adjust if necessary.
  4. Check Throttle Position (TP) sensor.
  5. Check Intake Manifold Pressure (IMP) sensor.
  6. Check Intake Air Temperature (IAT) sensor.
  7. Check intake air temperature and pressure sensor.
  8. Check EGR valve (Outback 3.0L).

POOR ACCELERATION

  1. Check Intake Manifold Pressure (IMP) sensor.
  2. Check Intake Air Temperature (IAT) sensor.
  3. Check intake air temperature and pressure sensor.
  4. Check Throttle Position (TP) sensor.
  5. Check fuel injection components; fuel injectors, fuel pressure regulator and fuel filter.
  6. Check fuel pump and fuel pump relay.
  7. Check Engine Coolant Temperature (ECT) sensor, if symptom occurs only in cold temperatures.
  8. Check Crankshaft Position (CKP) sensor, ensure component is securely installed.
  9. Check Camshaft Position (CMP) sensor, ensure component is securely installed.
  10. Check A/C switch and A/C cut relay.
  11. Check engine torque control signal circuit.
  12. Check ignition parts; ignitor, ignition coil and spark plugs.
  13. Check EGR valve (Outback 3.0L).

ENGINE STALLS, SAGS OR HESITATES DURING ACCELERATION

  1. Check Intake Manifold Pressure (IMP) sensor.
  2. Check Intake Air Temperature (IAT) sensor.
  3. Check intake air temperature and pressure sensor.
  4. Check Engine Coolant Temperature (ECT) sensor, if symptom occurs only in cold temperatures.
  5. Check Crankshaft Position (CKP) sensor, ensure component is securely installed.
  6. Check Camshaft Position (CMP) sensor, ensure component is securely installed.
  7. Check purge control solenoid valve.
  8. Check fuel injection components; fuel injectors, fuel pressure regulator and fuel filter.
  9. Check Throttle Position (TP) sensor.
  10. Check fuel pump and fuel pump relay.
  11. Check EGR valve (Outback 3.0L).

SURGE

  1. Check Intake Manifold Pressure (IMP) sensor.
  2. Check Intake Air Temperature (IAT) sensor.
  3. Check intake air temperature and pressure sensor.
  4. Check Engine Coolant Temperature (ECT) sensor, if symptom occurs only in cold temperatures.
  5. Check Crankshaft Position (CKP) sensor, ensure component is securely installed.
  6. Check Camshaft Position (CMP) sensor, ensure component is securely installed.
  7. Check fuel injection components; fuel injectors, fuel pressure regulator and fuel filter.
  8. Check Throttle Position (TP) sensor.
  9. Check fuel pump and fuel pump relay.
  10. Check EGR valve (Outback 3.0L).

SPARK KNOCK

  1. Check Intake Manifold Pressure (IMP) sensor.
  2. Check Intake Air Temperature (IAT) sensor.
  3. Check intake air temperature and pressure sensor.
  4. Check Engine Coolant Temperature (ECT) sensor.
  5. Check Knock Sensor (KS).
  6. Check fuel injection components; fuel injectors, fuel pressure regulator and fuel filter.
  7. Check fuel pump and fuel pump relay.

AFTER-BURN IN EXHAUST SYSTEM

  1. Check Intake Manifold Pressure (IMP) sensor.
  2. Check Intake Air Temperature (IAT) sensor.
  3. Check intake air temperature and pressure sensor.
  4. Check Engine Coolant Temperature (ECT) sensor, if symptom occurs only in cold temperatures.
  5. Check fuel injection components; fuel injectors, fuel pressure regulator and fuel filter.
  6. Check fuel pump and fuel pump relay.

Intermittent Simulation

To reproduce the conditions creating an intermittent fault, use the following methods

  1. Lightly vibrate component.
  2. Heat component.
  3. Wiggle or bend wiring harness.
  4. Spray component with water.
  5. Remove/apply vacuum source.

Monitor circuit/component voltage or resistance while simulating intermittent concern. If engine is running, monitor for self-diagnostic codes. Use test results to identify a faulty component or circuit.

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