Engine Controls - Trouble Shooting - No Codes: Other Mitsubishi Eclipse III

DIFFICULT TO START/NO START (CRANKS OKAY)

1. Check for minimum 8 volts present at battery while cranking engine.
2. Using scan tool, check for immobilizer system Diagnostic Trouble Codes (DTCs).
3. Using scan tool, check cranking speed (tach signal), power supply voltage, Crankshaft Position (CKP) sensor and Engine Coolant Temperature (ECT) sensor.
4. Using scan tool, perform actuator test for fuel pump.
5. Check for injector operating sound while cranking.
6. Check ignition system.
7. Check for injector clogging.
8. Check for fuel contamination.
9. Check compression pressure.
10. Ensure electrical harness, connectors and wires are not broken, bent or loose.

ROUGH OR UNSTABLE IDLE

1. If battery was recently disconnected, start and idle engine for 10 minutes, then recheck idle.
2. If hunting, clean throttle body.
3. Check Idle Air Control (IAC) motor.
4. Check for vacuum leaks.
5. Check PCV valve operation.
6. Check for injector operation sound.
7. Check fixed Speed Adjusting Screw (SAS).
8. Using scan tool, check closed throttle position switch (if applicable), IAT sensor, BARO sensor, ECT sensor, EVAP purge solenoid, EGR solenoid, front and rear HO2Ss, power steering pressure switch, A/C switch, Park Neutral Position (PNP) switch and IAC motor position values.
9. Check fuel pressure.
10. Using scan tool, perform actuator tests for EGR solenoid and purge solenoid.
11. Check ignition system.
12. Check purge control system.
13. Check compression pressure.
14. Check for fuel contamination.

ENGINE HESITATES, OR POOR ACCELERATION

1. Check for injector operation sound.
2. Check ignition system.
3. Using scan tool, check IAT sensor, BARO sensor, ECT sensor, TP sensor, and front and rear HO2Ss values.
4. Using scan tool, perform actuator tests for fuel injectors and EGR solenoid.
5. Check fuel pressure.
6. Check for vacuum leaks.
7. Check PCV valve operation.
8. Check for clogged injectors.
9. Check ignition system.
10. Check EGR system.
11. Check compression.
12. Check fuel filter and fuel line for clogging.
13. Ensure electrical harness, connectors and wires are not broken, bent or loose.

ENGINE SURGES

1. Using scan tool, perform actuator tests for fuel injectors.
2. Check wiring between injectors and ECM/PCM.
3. Check ignition timing.
4. Using scan tool, check closed throttle position switch (if applicable), IAT sensor, BARO sensor, ECT sensor, TP sensor, EGR solenoid and front and rear HO2S values.
5. Using scan tool, perform actuator test for EGR solenoid.
6. Check fuel pressure.
7. Check for vacuum leaks.
8. Check PCV valve operation.
9. Check for clogged injectors.
10. Check ignition system.
11. Check EGR system.

DETONATION OR KNOCKING

1. Check spark plugs for correct heat range.
2. Check fuel quality/octane.
3. Check for fuel contamination.
4. Check for intake system air leaks.
5. Check for carbon build-up in cylinders.
6. Check if head or deck has been resurfaced.

POOR FUEL MILEAGE

1. Check fuel system enters closed loop operation.
2. Check engine coolant temperature sensor.
3. Check intake air temperature sensor.
4. Check barometric pressure sensor (if applicable).
5. Check manifold absolute pressure sensor (if applicable).
6. Check throttle position sensor.
7. Check front Heated Oxygen Sensor (HO2S).
8. Check fuel pressure.
9. Check ignition timing.
10. Check camshaft timing.
11. Check compression pressure.
12. Check for fuel injector leakage.
13. Check fuel system for leaks.

Intermittent Simulation

To reproduce conditions creating an intermittent fault, use following methods

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

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