Engine Controls - Tests W/o Codes: Other Hyundai Sonata III

Spark Available

1. Verify ignition fuse is not blown.
2. Verify fusible link is not blown.
3. Verify air intake system is not restricted.
4. Ensure fuel system pressure and volume are correct.
5. Check for poor quality or contaminated fuel.
6. Check for use of fuel with high alcohol content.
7. Check exhaust system for restriction.

No Spark Available

1. Ensure secondary ignition system is in good condition.
2. Ensure pick-up coil air gap is correct.
3. Ensure ignition coil supply voltage is correct.
4. Ensure ignition coil primary resistance is correct.
5. Ensure ignition coil secondary resistance is correct.
6. Ensure ignitor resistance is correct.
7. Check ignitor primary leads for open or short circuit.
8. Ensure ECU has correct voltage supply and is properly grounded.

DIFFICULT TO START (CRANKS OKAY)

1. Ensure sufficient secondary spark is available.
2. Check air intake system for restriction.
3. Ensure vacuum hoses are not disconnected or damaged.
4. Ensure fuel system pressure is correct.
5. Ensure fuel injector operation is correct.
6. Ensure EGR valve operation is correct.
7. Ensure EGR valve closes completely.
8. Check for cracks or poor connections at throttle body.
9. Ensure ignition and valve timing are correct.
10. Ensure distributor pick-up coil air gap is correct.
11. Ensure distributor pick-up coil resistance is within specification.
12. Ensure ignition coil resistance is within specification.
13. Check coolant temperature sensor operation.
14. Check control relay operation.
15. Check power transistor operation.
16. Check operation of air induction valve.
17. Ensure electrical harness and connectors are not broken or loose.
18. Ensure ECU has correct voltage supply and is properly grounded.
19. Ensure engine has sufficient compression.

ENGINE SURGES

1. Ensure there are no vacuum leaks.
2. Ensure EGR valve operation is correct.
3. Ensure EGR valve closes completely.
4. Ensure fuel system pressure is correct and constant.
5. Ensure ignition timing is correct.

ROUGH OR UNSTABLE IDLE

1. Check IAC valve for malfunction.
2. Ensure fuel system pressure is correct.
3. Ensure idle speed is correct.
4. Check air intake system for restrictions.
5. Use stethoscope to verify operational noise coming from fuel injectors.
6. Ensure sufficient secondary spark is available in all cylinders.
7. Verify vacuum hose routing is correct and that there are no vacuum leaks.
8. Ensure fuel system pressure and volume are correct.
9. Check for EGR system malfunction.
10. Check coolant temperature sensor operation.
11. Check intake air temperature sensor operation.
12. Verify throttle position sensor has correct adjustment and resistance value.
13. Check air conditioner switch operation.
14. Check inhibitor switch operation (automatic transmission).
15. Check IAC servo drive signal and operation.
16. Check airflow sensor voltage output.
17. Check barometric pressure sensor voltage output.
18. Check crank angle sensor operation.
19. Check vehicle speed sensor operation.
20. Check TDC sensor or cylinder No. 1 TDC sensor operation.
21. Check electrical connections at fuel injectors.

EXCESSIVE FAST IDLE

1. Check throttle cable adjustment.
2. Verify vacuum hose routing is correct.
3. Ensure there are no vacuum leaks.
4. Ensure fuel system pressure and volume are correct.
5. Check coolant temperature sensor operation.

ENGINE STALLS

1. Ensure air intake system is not restricted.
2. Ensure PCV system operation is correct.
3. Check EGR system for correct operation.
4. Check for cracks or poor connections at throttle body.
5. Check coolant temperature sensor operation.
6. Ensure fuel system pressure is correct. Use ohmmeter to verify correct fuel injector resistance.
7. Verify correct throttle position sensor adjustment and resistance value.
8. Check for poor quality or contaminated fuel. Check for use of fuel with high alcohol content.

ENGINE LACKS POWER

1. Check throttle cable adjustment.
2. Verify air intake system is not restricted.
3. Check EGR system for correct operation.
4. Ensure fuel system pressure is correct. Use ohmmeter to verify correct fuel injector resistance.
5. Ensure base timing is correct and timing advance system is functional.
6. Check purge control valve operation.
7. Check vacuum switching valve operation.
8. Check throttle position sensor operation.
9. Check coolant temperature sensor operation.
10. Verify throttle valve opens completely when accelerator pedal is fully applied.
11. Check transmission for correct downshift (A/T).
12. Check exhaust system for restriction.

ENGINE MISFIRES OR HESITATES

1. Ensure vacuum hoses are not disconnected or damaged.
2. Ensure electrical harness, connectors and wires are not broken or loose.
3. Ensure fuel pressure is correct.
4. Check air conditioner switch operation.
5. Check air conditioner power relay operation.
6. Check airflow sensor voltage output.
7. Check barometric pressure sensor voltage output.
8. Check crank angle sensor operation.
9. Check coolant temperature sensor operation.
10. Check idle position switch operation.
11. Check ignition switch operation.
12. Check inhibitor switch operation (A/T).
13. Check intake air temperature sensor operation.
14. Check IAC servo drive signal and operation.
15. Check motor position sensor operation.
16. Check oxygen (O2) sensor voltage output.
17. Check power steering oil pressure switch operation.
18. Check throttle position sensor operation.
19. Check TDC sensor or cylinder No. 1 TDC sensor operation.

ENGINE RUNS ROUGH ON DECELERATION

1. Check IAC valve for malfunction.
2. Ensure fuel system pressure is correct.

AFTERBURN IN EXHAUST SYSTEM

1. Ensure there are no leaks in exhaust system.
2. Ensure base timing is correct, and timing advance system is functional.
3. Check throttle position sensor.
4. Check coolant temperature sensor.
5. Check IAC solenoid operation.
6. Check A/C vacuum solenoid valve (if equipped).

POOR FUEL MILEAGE

1. Ensure base timing is correct, and timing advance system is functional.
2. Ensure fuel system pressure is correct.
3. Check air conditioner switch operation.
4. Check airflow sensor voltage output.
5. Check barometric pressure sensor voltage output.
6. Check engine coolant temperature sensor operation.
7. Check idle position switch operation.
8. Check ignition switch operation.
9. Check inhibitor switch operation (A/T).
10. Check injector operation.
11. Check intake air temperature sensor operation.
12. Check motor position sensor operation.
13. Check oxygen (O2) sensor operation.
14. Check power steering oil pressure switch operation.
15. Check throttle position sensor operation.
16. Check TDC sensor or cylinder No. 1 TDC sensor operation.

DETONATION OR KNOCKING

1. Check engine oil level.
2. Check engine for overheating.
3. Verify base timing is correct.
4. Check for vacuum leaks.
5. Check EGR system operation.
6. Check for contaminated or poor quality fuel.
7. Check for carbon build-up in combustion chamber.
8. Ensure spark plug application is correct.
9. Ensure ECM application is correct.

Intermittent Simulation

To reproduce conditions creating intermittent fault, use 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. If engine is running, monitor for self-diagnostic codes. Use test results to identify a faulty component or circuit.