Engine Controls - Tests W/o Codes - Gasoline Dodge Caravan II

INTRODUCTION

Before diagnosing symptoms or intermittent faults, perform steps in appropriate BASIC TESTING and TESTS W/CODES (if applicable) articles in the ENGINE PERFORMANCE Section. Use this article to diagnose driveability problems that exist when a hard fault code is not present.

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

Use intermittent test procedures to locate driveability problems that do not occur while the vehicle is tested. These problems may noticeably affect driveability or cause CHECK ENGINE light to glow. Also use these test procedures if a soft (intermittent) trouble code was present but no problem is found during self-diagnostic testing.

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

SYMPTOM DIAGNOSIS

Symptom checks cannot be used properly unless problem occurs while vehicle is tested. To reduce diagnostic time, verify customer's complaint, ensure steps in appropriate BASIC TESTING and G - TESTS W/ CODES (if applicable) articles in the ENGINE PERFORMANCE Section are performed and visually inspect all systems before diagnosing a symptom. Symptoms available for diagnosis include the following.

1. No Start - Cold Engine
2. No Start - Warm Engine
3. Starts But Stalls
4. Hard To Start - Cold Engine
5. Erratic Idle - Warm-Up
6. Engine Surges
7. Backfiring
8. Incorrect Idle Speed
9. Hesitation - Acceleration
10. Hesitation - Coasting
11. Knocking
12. Engine Misfire - All Conditions
13. Insufficient Engine Power
14. Poor Fuel Economy
15. Excessive HC & NOx

NO START - COLD ENGINE

1. Ensure battery is fully charged.
2. Check for contaminated fuel.
3. Check spark plugs.
4. Check fuel pump fuse(s).
5. Check in-line fuse to control unit (if applicable).
6. Ensure ignition timing and fuel pressure are correct.
7. Check fuel injectors.
8. Ensure timing belt is not broken (if applicable).
9. Ensure ignition coil resistance is correct.
10. Ensure rotor, distributor and spark plug wires are okay.
11. Check ignition control unit.
12. Check coolant temperature sensor and connector.
13. Check throttle switch and connector (if applicable).
14. Check engine speed sensor.
15. Check airflow sensor.

NO START - WARM ENGINE

1. Ensure fuel pressure is correct.
2. Check for gasoline in oil.
3. Ensure fuel injectors are not leaking.
4. Check ignition and sensor wires for proper connection.
5. Ensure spark plugs are not fouled.
6. Check ignition and coil circuit.
7. Check engine speed sensor.
8. Check throttle switch and connector (if applicable).

STARTS BUT STALLS

1. Check coolant temperature sensor.
2. Check ignition and sensor wires for proper connection.
3. Check fuel injectors.
4. Check throttle switch and connector (if applicable).
5. Check engine speed sensor.

HARD TO START - COLD ENGINE

1. Check spark plugs.
2. Check distributor (if applicable).
3. Ensure fuel pressure is correct.
4. Check ignition timing.
5. Check throttle switch and connector (if applicable).

ERRATIC IDLE - WARM-UP

1. Check throttle switch and connection (if applicable).
2. Check coolant temperature sensor and connection.
3. Check air temperature sensor (if applicable).
4. Ensure spark plugs are not fouled.
5. Check ignition and sensor wires for proper connection.
6. Check distributor (if applicable).
7. Check ignition and coil circuit.
8. Check intake system.
9. Check engine speed sensor.
10. Check throttle switch and connector (if applicable).
11. Check MAP sensor (if applicable).

ENGINE SURGES

1. Check ignition and fuel system.
2. Check for vacuum leaks.
3. Check EGR system.

BACKFIRING

1. Ensure ignition timing is correct.
2. Ensure timing belt/chain has not jumped.
3. Check distributor (if applicable).
4. Check for gasoline in oil.
5. Ensure fuel injectors are not leaking.
6. Check spark plugs.
7. Check ignition and coil circuit.
8. Check engine speed sensor.
9. Check throttle switch and connector.
10. Check exhaust system.

INCORRECT IDLE SPEED

1. Check fuel injectors.
2. Check intake system for leaks.
3. Check coolant temperature sensor.
4. Check throttle switch and connector (if applicable).
5. Check distributor (if applicable).

HESITATION - ACCELERATION

1. Check ignition and sensor wires for proper connection.
2. Check distributor cap for moisture and carbon tracking.
3. Ensure spark plug wires are okay.
4. Ensure spark plugs are not fouled.
5. Check MAP sensor (if applicable).
6. Check throttle switch and connector (if applicable).
7. Check ignition and coil circuit.
8. Check engine speed sensor.

HESITATION - COASTING

1. Check fuel injectors.
2. Check ignition and sensor wires for proper connection.
3. Check throttle switch and connector.
4. Check engine speed sensor.
5. Check for gasoline in oil.

KNOCKING

1. Check ignition and coil circuit.
2. Check for defect in throttle body power system.
3. Check for restrictions at throttle body air inlet.
4. Check EGR system.
5. Ensure spark plugs fire.
6. Check knock sensor (if applicable).
7. Check throttle switch and connector (if applicable).
8. Check engine speed sensor.
9. Check MAP sensor (if applicable).

ENGINE MISFIRE - ALL CONDITIONS

1. Check fuel injectors.
2. Check ignition and sensor wires for proper connection.
3. Check ignition and coil circuit.
4. Check for gasoline in oil.
5. Check intake and exhaust system.
6. Check throttle switch and connector (if applicable).
7. Check for vacuum leaks.
8. Check engine speed sensor.
9. Check MAP sensor (if applicable).

INSUFFICIENT ENGINE POWER

1. Check fuel injectors.
2. Check for air inlet restriction.
3. Ensure fuel pressure is correct.
4. Check airflow sensor.
5. Check for restricted exhaust.
6. Check coolant temperature sensor.
7. Check air temperature sensor (if applicable).
8. Check throttle switch and connector (if applicable).
9. Check ignition and coil circuit.
10. Check MAP sensor (if applicable).
11. Check engine speed sensor.
12. Check intake and exhaust system.
13. Check EGR system.

POOR FUEL ECONOMY

1. Check for leaky fuel injectors.
2. Ensure spark plugs are not fouled.
3. Check for faulty oxygen sensor.
4. Check throttle switch and connector.
5. Check for poor wire connections.
6. Check engine speed sensor.
7. Check for gasoline in oil.
8. Check MAP sensor (if applicable).

EXCESSIVE HC & NOx

1. Check for gasoline in oil.
2. Check for leaky fuel injectors.
3. Check for faulty oxygen sensor.
4. Check ignition and sensor wires for poor connection.
5. Check engine speed sensor.
6. Check throttle switch and connector (if applicable).
7. Check for vacuum leaks.

INTERMITTENT PROBLEM DIAGNOSIS

Intermittent fault testing requires duplicating circuit or component failure to identify problem. These procedures may lead to 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 digital volt-ohmmeter (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.

TEST PROCEDURES

Following methods may reproduce conditions which create an intermittent fault which may be identified during testing

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 fault. If engine is running, monitor for self-diagnostic codes. Use test results to identify a faulty component or area to be closely inspected for problem.