Engine Controls - Tests W/o Codes - 8.0l Engine Dodge Pickup R2500

INTRODUCTION

Before diagnosing symptoms or intermittent faults, perform steps in appropriate BASIC TESTING - GASOLINE and TESTS W/CODES articles. Use this article to diagnose driveability problems existing when a hard fault code is not present.

Note. Some driveability problems may have been corrected by manufacturer with a revised Powertrain Control Module (PCM). Check with manufacturer for latest PCM application.

Symptom checks direct the 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 when the vehicle is being tested. These problems may cause a noticeable driveability problem or cause the Malfunction Indicator Light (MIL) to illuminate on some vehicles. These test procedures should also be used if a soft (intermittent) trouble code is present, but no problem is found during self-diagnostic testing.

Note. For specific testing procedures, see appropriate TESTS W/CODES article. For specifications, see appropriate ADJUSTMENTS or SPECIFICATIONS article.

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 appropriate BASIC TESTING - GASOLINE and TESTS W/CODES articles are performed before diagnosing a symptom. Symptoms available for diagnosis are as follows

1. No Start Or Hard Start
2. Starts But Stalls
3. Hard To Start - Cold Engine
4. Erratic Idle Or Surging
5. Backfiring
6. Incorrect Idle Speed
7. Hesitation - Acceleration
8. Knocking
9. Engine Misfire - All Conditions
10. Insufficient Engine Power
11. Poor Fuel Economy
12. Excessive HC & CO

NO START OR HARD START

1. Ensure battery is fully charged.
2. Check spark plugs.
3. Perform spark test.
4. Check for sufficient fuel and fuel contamination.
5. Check fuses.
6. Ensure ignition timing and fuel pressure are correct.
7. Check fuel injectors.
8. Check crank and cam sensors.
9. Ensure timing belt or chain has not jumped.
10. Ensure ignition coil resistance is correct.
11. Ensure rotor, distributor (if applicable) and plug wires are okay.
12. Check coolant temperature sensor and connector.
13. Check TP sensor and connector.
14. Check airflow sensor.
15. Check anti-theft system (if applicable).
16. Check for contaminated fuel.
17. Check for vacuum leaks.
18. Ensure fuel pressure is correct.
19. Check for gasoline in oil.
20. Check ignition and sensor wires for proper connection.

STARTS BUT STALLS

1. Check fuel pressure.
2. Check coolant temperature sensor.
3. Check ignition and sensor wires for proper connection.
4. Check for vacuum leaks.
5. Check TP sensor and connector.
6. Check crank and cam sensors.
7. Check idle air control motor.
8. Check anti-theft system.

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 TP sensor and connector.
6. Check crank and cam sensors.
7. Check idle air control motor.

ERRATIC IDLE OR SURGING

1. Check for vacuum leaks.
2. Check spark plugs.
3. Check distributor (if applicable).
4. Ensure fuel pressure is correct.
5. Check idle air control motor.
6. Check minimum idle airflow.
7. Check crankshaft position sensor.
8. Check MAP sensor.
9. Check TP sensor and connector.
10. Check ignition timing.
11. Check oxygen sensor switching.

BACKFIRING

1. Check for vacuum leaks.
2. Ensure ignition timing is correct.
3. Ensure timing belt or chain has not jumped.
4. Check distributor (if applicable).
5. Ensure fuel injectors are not leaking.
6. Check spark plugs and plug wires.
7. Check ignition and coil circuit.
8. Check crank and cam sensors.
9. Check TP sensor and connector.
10. Check exhaust system.

INCORRECT IDLE SPEED

1. Check intake system for leaks.
2. Check throttle linkage for binding.
3. Check idle air control motor.
4. Check coolant temperature sensor.
5. Check TP sensor and connector.
6. Check distributor (if applicable).
7. Check for vacuum leaks.

HESITATION - ACCELERATION

1. Check for vacuum leaks.
2. Check ignition and sensor wires for proper connection.
3. Check distributor (if applicable) cap for moisture.
4. Check idle air control motor.
5. Check minimum idle airflow.
6. Ensure spark plug wires are okay.
7. Ensure spark plugs are not fouled.
8. Check MAP sensor.
9. Check TP sensor and connector.
10. Check ignition and coil circuit.
11. Check crank and cam sensors.

KNOCKING

1. Check ignition timing.
2. Check ignition and coil circuit.
3. Check TP sensor and connector.
4. Check engine mechanical condition.
5. Check MAP sensor.

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 crank and cam sensors.
5. Check for gasoline in oil.
6. Check TP sensor and connector.
7. Check for vacuum leaks.
8. Check engine mechanical condition.
9. Check MAP sensor.

INSUFFICIENT ENGINE POWER

1. Check fuel injectors.
2. Ensure fuel pressure is correct.
3. Check for air inlet restriction.
4. Check for restricted exhaust.
5. Check coolant temperature sensor.
6. Check crank and cam sensors.
7. Check TP sensor and connector.
8. Check ignition and coil circuit.
9. Check MAP sensor.

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 and fouled spark plugs.
6. Check for contaminated fuel.
7. Check crank and cam sensors.
8. Check MAP sensor.

EXCESSIVE HC & CO

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 crank and cam sensors.
6. Check TP sensor and connector.
7. Check for vacuum leaks.

INTERMITTENT PROBLEM DIAGNOSIS

Intermittent fault testing requires duplicating circuit or component failure to identify the problem. These procedures may lead to PCM setting a Diagnostic Trouble Code (DTC) which may help in diagnosis.

If problem vehicle does not produce DTC, 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.
5. Remove/apply vacuum source.

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