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Engine Controls - Trouble Shooting - No Codes Subaru Impreza WRX GD/GG рестайлинг

Testing & Diagnostics ~1082 words

INTRODUCTION

Before diagnosing symptoms or intermittent faults, perform steps in BASIC DIAGNOSTIC PROCEDURES and SELF-DIAGNOSTICS articles. Use this article to diagnose driveability problems existing when a hard fault code is not present.

Note. Some driveability problems may have been corrected by manufacturer with a revised Electronic Control Module (ECM). Check with manufacturer for latest computer application.

Symptom checks can direct the technician to malfunctioning component(s) for further diagnosis. A symptom should lead to a specific component, system test or adjustment.

Use intermittent test procedures to locate driveability problems that DO NOT occur when the vehicle is being tested. These test procedures should also be used if a soft (intermittent) trouble code was present, but no problem was found during self-diagnostic testing.

Note. For specific testing procedures, see SYSTEM & COMPONENT TESTING article. For specifications, see ON-VEHICLE ADJUSTMENTS or SERVICE & ADJUSTMENT SPECIFICATIONS article.

SYMPTOM DIAGNOSIS

Symptom checks cannot be used properly unless problem occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC DIAGNOSTIC PROCEDURES and SELF-DIAGNOSTICS articles were performed before diagnosing a symptom. The following symptoms are available for diagnosis

  1. «Engine Stalls During Idle»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes__engine-stalls-during-idle)
  2. «Rough Idle»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes__rough-idle)
  3. «Engine Does Not Return To Idle»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes__engine-does-not-return-to-idle)
  4. «Poor Acceleration»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes__poor-acceleration)
  5. «Engine Stalls, Sags Or Hesitates During Acceleration»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes__engine-stalls-sags-or-hesitates-during)
  6. «Surge»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes__surge)
  7. «Spark Knock»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes__spark-knock)
  8. «After-Burn In Exhaust System»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes__after-burn-in-exhaust-system)

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 PROBLEM DIAGNOSIS

Intermittent fault testing requires duplicating circuit or component failure to identify problem. These procedures may lead to the computer setting a fault code, which may help in diagnosis.

If problem vehicle does not produce fault codes, monitor voltage or resistance with a DVOM while attempting to reproduce the conditions causing intermittent fault. A status change on DVOM indicates a fault has been located.

Use a DVOM to pinpoint faults. When monitoring voltage, ensure ignition switch is in ON position or engine is running. Ensure ignition switch is in OFF position, or negative battery cable is disconnected when monitoring circuit resistance. Status changes on DVOM during test procedures indicate area of fault.

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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