2018 Ford Explorer V6 3.5L – Fast Idle

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The 2018 Ford Explorer V6 3.5L has had reports of a “Fast Idle” issue, where the engine idle speed remains higher than expected, even after the vehicle has warmed up or when stopped. This can be frustrating for drivers, as it may lead to increased fuel consumption, rough shifting, and potential engine wear. This guide outlines common causes of a fast idle, such as issues with the throttle body, idle air control valve, or intake air leaks. Following these steps can help you troubleshoot the problem to restore smooth idle performance.

Procedure

Note: Make sure the vehicle has been driven for 5 miles consecutively before diagnosing.

A. Base Engine

1. Check for air leaks on the intake air system; or components and vacuum lines connected to the system (such as Positive Crankcase Ventilation (PCV), Exhaust Gas Recirculation (EGR) valve).

B. Cooling System

1. Start and run the engine and verify the engine operates at normal temperature.

C. Intake Air System

1. Retrieve the Diagnostic Trouble Codes (DTCs) from the Powertrain Control Module (PCM).

2. Check engine idle speed.

3. Check for vacuum leaks in the intake air system from the Mass Airflow (MAF) sensor to the intake manifold such as:

• Damaged or torn intake air ducting.
• Loose fittings where the intake air duct attaches to the air filter housing or throttle body.
• EGR valve gasket leaking into the intake manifold.
• Issues with the intake manifold assembly or gasket.
• Defects in the EGR valve diaphragm or control solenoid.
• Faulty connections or hoses in the vacuum supply.

4. Check for restriction between the intake air ducting and the throttle body.

5. Check the harness and connection of the Intake Manifold Tuning Valve (IMTV) for damage.

6. Check the voltage between Pin 1 of the IMTV Actuator connector harness and the negative terminal of the battery.

• Expectation: greater than 10.5V.

7. Check for open-circuit issues between Pin 3 of the IMTV Actuator connector harness and the PCM connector harness.

8. Check for short-to-ground issues between the PCM connector harness and the ground.

9. Check for short-to-voltage issues between Pin 3 of the IMTV Actuator connector harness and the ground.

10. Check the lamp illumination in the Key ON Engine OFF (KOEO) and Key ON Engine Running (KEOR) condition between Pin 1 and Pin 3 of the IMTV Actuator connector harness.

11. Check the operation of the IMTV Actuator manually.

12. Check the functionality of the IMTV Actuator.

13. Check the Intake Manifold Runner Control (IMRC) condition as below:

• Disconnected or damaged linkages.
• Correct connection, damage or leaks between the IMRC solenoid and vacuum line.
• Restricted linkage.
• Proper operation of spring tension.
• Proper operation of IMRC manually.

14. Check for IMRC functionality.

15. Check for open-circuit issues between:

• Pin 2 and Pin 1 of the IMRC Solenoid Bank 1/Bank 2 component.
• Pin 1 of the IMRC Solenoid Bank 1/Bank 2 connector harness and the ground.
• Pin 2 of the IMRC Solenoid Bank 1/Bank 2 connector harness and the PCM.
• Pin 3 and Pin 1 of the IMRC Sensor Bank 1/Bank 2 connector harness.

16. Check for short-to-ground issues between Pin 2 of the IMRC Sensor Bank 1/Bank 2 connector harness and the ground.

17. Check for short-to-voltage issues between Pin 3 of the IMRC Sensor Bank 1/Bank 2 connector harness and the ground.

18. Perform preliminary diagnostics for idle air concerns.

19. Monitor the Intake Air System Parameter IDs (PIDs) such as:

• ECT TEMP and ECT1 TEMP
• ETC_TRIM (ANGL)
• IACTRIM (NUM) and IACKAM2 (NUM)

20. Check PCM operation.

D. Additional Testing

Note: The following steps outline the necessary checks to ensure the vehicle operates normally with the ignition turned OFF.

1. Begin by inspecting the battery and charging system voltages.

2. Conduct a PCM Power Relay component test.

3. Turn the ignition ON and measure the voltage between Pin 3 of the PCM Power Relay connector harness and ground.

• Expected result: Above 10.5V.

4. Turn the ignition OFF, then inspect for an open circuit between Pin 1 of the PCM Power Relay connector harness and Pin B20 of the PCM connector. Turn the ignition ON and check for short-to-voltage issues between Pin B20 of the PCM connector and ground.

5. Measure the voltage between Pin B64 of the PCM connector and ground.

• Expected result: Above 10.5V.

6. Turn the ignition OFF and check for an open circuit between Pin 5 of the PCM Power Relay connector harness and Pins B99 and B97 of the PCM connector.

7. Inspect for short-to-ground issues between Pin B20 of the PCM connector and ground.

8. Check for short-to-voltage issues between Pin B64 of the PCM connector and ground.

9. Disconnect the injector and inspect for an open circuit between Pin E18 of the PCM connector and Pin 2 of the injector connector.

10. Use the Scan Tool to observe the INJPWR_M PID value when turning the ignition ON, then OFF.

• Expected result: Change from above 10.5V to 0V.

Additional Procedure for Other Scenarios:

1. Use the Scan Tool to check and clear any DTCs from the PCM.

2. Use the Live Data function to select and monitor PIDs related to the suspected system issue.

3. Confirm if any concerns or symptoms appear based on the PID values recorded in Step 2; if so, proceed to Step 7.

4. Attempt to recreate the symptom-based on Freeze Frame data; if successful, proceed to Step 7.

5. Recreate symptoms and monitor relevant PIDs during different road test conditions:

• Hot idle test
• 48 km/h (30 mph) test
• 88 km/h (55 mph) test

6. Perform circuit testing related to the suspected system issue:

Input circuit testing

• KOEO input test for PCM sensors
• KOER input test for PCM sensors
• KOEO water soak test for PCM sensors (excluding high-voltage circuits)
• KOER water soak test for PCM sensors (excluding high-voltage circuits)

Output circuit testing:

• KOER wiggle test for PCM sensors
• KOER output test for PCM actuators
• KOEO water soak test for PCM actuators (excluding high-voltage circuits)
• KOER water soak test for PCM actuators

7. Finally, inspect for any intermittent mechanical concerns.

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