Engine Controls - Tests W/o Codes Hyundai Elantra I

INTRODUCTION

Before diagnosing symptoms or intermittent faults, perform steps in BASIC TESTING and TESTS W/CODES articles in the ENGINE PERFORMANCE Section. Use this article to diagnose driveability problems existing when a hard fault code is not present or vehicle is not equipped with a self-diagnostic system.

Note. Some driveability problems may have been corrected by manufacturer with a revised computer calibration chip or computer control unit. Check with manufacturer for latest chip or computer application.

Symptom checks can direct 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 while 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 I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. For specifications, see SPECIFICATIONS or ADJUSTMENTS articles in the ENGINE PERFORMANCE Section.

SYMPTOM DIAGNOSIS

Symptom checks cannot be used properly unless problem occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC TESTING and TESTS W/CODES articles in the ENGINE PERFORMANCE Section were performed before diagnosing a symptom. Symptoms available for diagnosis include following

1. Will Not Start (Cranks Okay)
2. Difficult To Start (Cranks Okay)
3. Engine Surges
4. Rough Or Unstable Idle
5. Excessive Fast Idle
6. Engine Stalls
7. Engine Lacks Power
8. Engine Misfires Or Hesitates
9. Engine Runs Rough On Deceleration
10. Afterburn In Exhaust System
11. Poor Fuel Mileage
12. Detonation Or Knocking
13. Fails Emission Test

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 ISC 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 ISC 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 No. 1 cylinder TDC sensor operation.
21. Check electrical connections at fuel injectors.
22. Check O2 sensor for fluctuating voltage output (0-3.0 volts) with engine at 2000 RPM.

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 ISC 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 No. 1 cylinder TDC sensor operation.

ENGINE RUNS ROUGH ON DECELERATION

1. Check ISC 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 ISC 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 No. 1 cylinder 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 ECU application is correct.

FAILS EMISSION TEST

1. Ensure air intake system is not restricted.
2. Ensure engine is at normal operating temperature.
3. Ensure fuel system pressure is correct.
4. Verify base timing is correct.
5. Check for correct PCV valve operation.
6. Check crankcase for gasoline contamination.
7. Check ISC solenoid.
8. Check EGR system for correct operation.
9. Check purge control valve operation.
10. Ensure throttle position sensor has correct adjustment and resistance value.
11. Check operation of coolant temperature sensor.
12. Ensure exhaust system is not restricted.

INTERMITTENT PROBLEM DIAGNOSIS

Intermittent fault testing requires duplicating circuit or component failure to identify problem. These procedures may lead to computer setting fault code (on some systems) which may help in diagnosis.

If problem vehicle does not produce fault codes, monitor voltage or resistance values using a DVOM while attempting to reproduce 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 vehicle is running. When monitoring circuit resistance, ensure ignition switch is in OFF position or negative battery cable is disconnected. Status change on DVOM during test procedures indicates area of fault.

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.