2018 Ford Explorer V6 3.5L – Slow Return to Idle

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The 2018 Ford Explorer V6 3.5L can experience a "slow return to idle" issue, where the engine takes longer than expected to settle back to a normal idle speed after the warming-up process. This can result in higher-than-normal idle speeds momentarily after releasing the throttle. Causes for this issue may include a malfunctioning throttle body, carbon buildup, or other components affecting the throttle response, such as the idle air control valve or the Powertrain Control Module (PCM). Addressing this problem may require cleaning the throttle body, checking for PCM updates, or other calibrations to restore smooth idle response.

Procedure

Note: Start by using a Scan Tool to retrieve any Diagnostic Trouble Codes (DTCs). This will help ensure that the symptom you're experiencing isn't related to any stored DTCs. If DTCs are found, address those first, as resolving them may correct the symptom.

A. Positive Crankcase Ventilation (PCV) System

1. Check for leaks or restrictions on the PCV valve, hoses, and connections.

2. Verify:

• Maintenance schedule on the PCV system.
• Part number.
• Cleanness of the components.
• Connections between components.

3. Inspect the PCV System for:

• Disconnection, damage, and restriction on the vacuum/intake air system/PCV lines between the engine and other components of the system.
• Damaged or pinched PCV O-ring seal.
• Incorrectly installed oil level indicator and oil cap.
• Damaged oil level indicator O-ring seal.

4. Monitor the CRNKCAS_P_V Parameter ID (PID).

• Expectation: 3.6 – 4.3V.

5. Check the voltage between Pin 3 and Pin 2 of the Crankcase Pressure Sensor Connector harness.

• Expectation: 4.5 – 5.5V.

6. Check for open-circuit issue between the Pin 1 Crankcase Pressure Sensor Connector harness and the PCM Connector harness.

7. Check for short-to-ground and short-to-voltage issues between the Pin 1 Crankcase Pressure Sensor Connector harness and the ground.

8. Inspect for intermittent mechanical concerns.

9. Check for the presence of a vacuum in the PCV system.

B. Intake Air System

1. Retrieve DTCsfrom the PCM.

2. Check the 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.
• Exhaust Gas Recirculation (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 issue between Pin 3 of the IMTV Actuator connector harness and the PCM connector harness.

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

9. Check for short-to-voltage issue 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 for proper operation of the IMTV Actuator manually.

12. Check for proper functionality of the IMTV Actuator.

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

• Disconnected or damaged linkages.
• Inspect the IMRC solenoid and vacuum line for correct connection, damage, or leaks.
• Inspect the linkage for restrictions.
• Inspect spring tension operation.
• Inspect the IMRC operation manually.

14. Check for proper IMRC functionality.

15. Check for open-circuit issue 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 issue between Pin 2 of the IMRC Sensor Bank 1/Bank 2 connector harness and the ground.

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

18. Perform the preliminary diagnostic for idle air concerns.

19. Monitor the Intake Air System PIDs such as:

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

20. Check for proper PCM operation.

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