Engine Controls - Tests W/o Codes Suzuki Swift II

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 the technician to malfunctioning component(s) for further diagnosis. A symptom should lead to a specific component, system test or an 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.

Most intermittent problems are caused by faulty electrical connections or wiring. Perform careful inspection of suspect circuits for

1. Poor mating of coupler halves, or terminals not fully seated in coupler body (backed out).
2. Terminals damaged or improperly formed. Reform coupler terminals in problem circuit to increase contact tension.
3. Poor terminal-to-wire connection.

Note. For specific testing procedures, see I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. For specifications, see ADJUSTMENTS or SPECIFICATIONS articles in the ENGINE PERFORMANCE Section.

SYMPTOM DIAGNOSIS

Symptom checks cannot be used properly unless the problem occurs while the 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

1. Difficult Or No Start (Cranks Okay)
2. Engine Misfires Or Has Lack Of Power
3. Rough Or Unstable Idle
4. Engine Hesitates
5. Engine Surges
6. Spark Knock/Detonation
7. Poor Fuel Mileage
8. Fails Emission Test
9. Overheating

DIFFICULT OR NO START (CRANKS OKAY)

1. Check for dirty or clogged fuel filter.
2. Check for lack of fuel in tank.
3. Check fuel pressure and volume.
4. Check for contaminated fuel.
5. Check for vacuum leaks.
6. Check for poor compression.
7. Check for blown ignition coil fuse.
8. Check for cracked distributor cap or rotor.
9. Check ignition and valve timing.
10. Check spark plugs.
11. Check for adequate spark with a spark tester.
12. Check EGR system.
13. Check pick-up coil air gap (if equipped).
14. Check for faulty ignitor (if equipped).
15. Check for faulty pick-up coil (if equipped).
16. Check for faulty coolant (water) temperature sensor.
17. Check for faulty air temperature sensor (if equipped).
18. Check for faulty airflow sensor (if equipped).
19. Check for faulty noise suppressor (if equipped).
20. Check for faulty air valve (if equipped).
21. Check for faulty ignition coil.
22. Check for faulty throttle opener (if equipped).
23. Check for faulty power unit (if equipped).
24. Check for faulty crank angle sensor (if equipped).
25. Check for malfunctioning ECM.
26. Check for malfunctioning PCV valve.
27. Check for malfunctioning electronic fuel injection system.
28. Check for slipped or broken timing belt.

ENGINE MISFIRES OR HAS LACK OF POWER

1. Check ignition and valve timing.
2. Check spark plugs.
3. Check for leaking or loose spark wires.
4. Check for adequate spark with a spark tester.
5. Check for worn distributor terminals.
6. Check for malfunctioning distributor mechanical or vacuum advance (if equipped).
7. Check cooling system.
8. Check for dirty or clogged fuel filter.
9. Check for contaminated fuel.
10. Check for clogged air filter.
11. Check for low compression.
12. Check for vacuum leaks.
13. Check for malfunctioning electronic fuel injection system.
14. Check for malfunctioning EGR valve.
15. Check for dragging brakes.
16. Check for slipping clutch.
17. Check for low auto transmission fluid level.

ROUGH OR UNSTABLE IDLE

1. Check for play in throttle cable.
2. Check for contaminated fuel.
3. Check fuel pressure.
4. Check for clogged air filter.
5. Check for vacuum leaks.
6. Check cooling system.
7. Check compression.
8. Check spark plugs.
9. Check for leaking or loose spark wires.
10. Check for adequate spark with a spark tester.
11. Check idle speed.
12. Check for cracked distributor cap.
13. Check for worn distributor terminals.
14. Check ignition and valve timing.
15. Clogged MAP sensor (pressure sensor) vacuum hose (if equipped).
16. Check for faulty ECM.
17. Check for faulty air valve (if equipped).
18. Check for faulty coolant (water) temperature sensor.
19. Check for faulty air temperature sensor (if equipped).
20. Check for faulty A/C vacuum switching valve (if equipped).
21. Check for faulty Idle Speed Control (ISC) solenoid valve (if equipped).
22. Check for faulty throttle opener system (if equipped).
23. Check for malfunctioning EGR valve.
24. Check for malfunctioning PCV valve.
25. Check for malfunctioning electronic fuel injection system.

ENGINE HESITATES

1. Check fuel pressure.
2. Check for clogged fuel filter.
3. Check for contaminated fuel.
4. Check for clogged air filter.
5. Check ignition and valve timing.
6. Check spark plugs.
7. Check for adequate spark with a spark tester.
8. Check for leaking or loose spark wires.
9. Check cooling system.
10. Check for low compression.
11. Check for vacuum leaks.
12. Check throttle position sensor (if equipped).
13. Check for clogged MAP sensor (pressure sensor) vacuum hose (if equipped).
14. Check for faulty ECM.
15. Check for faulty coolant (water) temperature sensor.
16. Check for malfunctioning electronic fuel injection system.
17. Check for malfunctioning EGR valve.

ENGINE SURGES

1. Check spark plugs.
2. Check for adequate spark with a spark tester.
3. Check for leaking or loose spark wires.
4. Check fuel pressure.
5. Check for clogged fuel filter.
6. Check for Damaged or kinked fuel lines.
7. Check for vacuum leaks.
8. Check for cracked distributor cap or rotor.
9. Check for malfunctioning distributor mechanical or vacuum advance (if equipped).
10. Check ignition and valve timing.
11. Check for faulty ECM.
12. Check for malfunctioning electronic fuel injection system.
13. Check for malfunctioning EGR valve.

SPARK KNOCK/DETONATION

1. Check cooling system.
2. Check fuel pressure.
3. Check spark plugs.
4. Check for leaking or loose spark wires.
5. Check for adequate spark with a spark tester.
6. Check ignition and valve timing.
7. Check for clogged fuel filter.
8. Check for vacuum leaks.
9. Check for excessive combustion chamber deposits.
10. Check for faulty throttle position sensor (if equipped).
11. Check for faulty coolant (water) temperature sensor.
12. Check for engine overheating.
13. Check for faulty MAP (pressure) sensor (if equipped).
14. Check for malfunctioning electronic fuel injection system.
15. Check for malfunctioning EGR valve.

POOR FUEL MILEAGE

1. Check for fuel leaks.
2. Check fuel pressure.
3. Check for clogged air filter.
4. Check compression.
5. Check cooling system.
6. Check ignition and valve timing.
7. Check spark plugs.
8. Check for adequate spark with a spark tester.
9. Check for leaking or loose spark wires.
10. Check for faulty throttle position sensor (if equipped).
11. Check for faulty coolant (water) temperature sensor.
12. Check form thermostat out of order.
13. Check for faulty ECM.
14. Check for high idle RPM.
15. Check for malfunctioning electronic fuel injection system.
16. Check for malfunctioning distributor mechanical or vacuum advance (if equipped).
17. Check for malfunctioning EGR valve.
18. Check for brakes dragging.
19. Check for clutch slipping.
20. Check for low auto transmission fluid.
21. Check for improper tire pressure.

FAILS EMISSION TEST

1. Check for clogged air filter.
2. Check for engine not at normal operating temperature.
3. Check for fuel leakage from injectors.
4. Check for fuel pressure out of specification.
5. Check for faulty coolant (water) temperature sensor.
6. Check for faulty air temperature sensor (if equipped).
7. Check for faulty ECM.
8. Check for faulty EGR system.
9. Check for improper ignition timing.
10. Check for malfunctioning ignition system.
11. Check for lead contamination in catalytic converter.
12. Check for misrouted vacuum hoses.
13. Check for poor compression.
14. Check for vacuum leaks.

OVERHEATING

1. Check for insufficient coolant.
2. Check for loose water pump belt.
3. Check for inoperative thermostat.
4. Check for poor water pump performance.
5. Check for improper ignition timing.
6. Check for clogged or leaky radiator.
7. Check for improper engine oil grade.
8. Check for clogged oil filter.
9. Check for not enough oil.
10. Check for poor oil pump performance.
11. Check for oil leak.
12. Check for dragging brakes.
13. Check for blown cylinder head gasket.

INTERMITTENT PROBLEM DIAGNOSIS

Intermittent fault testing requires duplicating circuit or component failure to identify the problem. These procedures may lead to the computer setting a 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 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 mist.
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.