My Ford Explorer idles too high - I've cleaned the throttle body, replaced IAC valve (needed new one) & throttle cable is low as it can go. Any suggestions?

The 2007 Ford Explorer Sport Trac does not utilize the once-common idle air control (IAC) valve. Instead, an electronic throttle body is used. An electronic throttle body is a traditional butterfly throttle valve that has an electric motor attached to it. Instead of opening via a throttle cable, it is opened by the powertrain control module (PCM) when the accelerator pedal position (APP) sensor (which is the gas pedal) is pressed. The PCM also adjusted the throttle blade position in order to achieve proper idle speeds. Often times idle problems with this type of electronic throttle body are caused by carbon buildup around the throttle plate, in the bore of the throttle body. In fact, this is such a common problem with this particular vehicle that Ford released technical service bulletin (TSB) #12-7-4 to address the RPM fluctuation and hard start symptoms and advises to clean the throttle body. Alternatively, the throttle body can and may need to be replaced. You can read more about this issue here: https://www.yourmechanic.com/article/how-to-replace-a-throttle-body-due-to-carbon-build-up-on-most-vehicles-by-ty-thompson

Try taking pff your throttle body and cleaning it and also check and see if your throttle cable is tight or try loosening it and see if the throttle drops. Could also be a bad o2 sensor staying in open circut

Clean the Throttle Body with CRC Throttle Body Cleaner

If you have an IAC Valve (idle air control solenoid) clean it first & see if that helps with the idle

P1506 - Idle Air Control (IAC) Overspeed Error This DTC is set when the PCM detects engine idle speed that is greater than the desired rpm.

• IAC circuit short to GND
• Damaged IAC valve

Disconnect IAC valve and look for little or no change in engine rpm as an indication of a stuck or damaged valve.
Ford Idle Air Control IAC valve test how to adjust minimum idle speed
Ford Idle Air Control Valve Diagnostics High Idle DTC P1506

change the idle air control valve.

Idle Air Control (IAC) Valve OPERATION The Idle Air Control (IAC) valve controls the engine idle speed and dashpot functions. The valve is located on the side of the throttle body. This valve allows air, determined by the Powertrain Control Module (PCM) and controlled by a duty cycle signal, to bypass the throttle plate in order to maintain the proper idle speed. Fig. 1: Typical Idle Air Control (IAC) valve which is mounted to the throttle body - cutaway view shows air bypass direction
--- REMOVAL & INSTALLATION

1. Disconnect the negative battery cable. To remove the IAC valve, first disconnect the negative battery cable, then the IAC wire harness plug
   Next, remove the two IAC valve attaching bolts . . .
   . . . and pull the valve from the intake manifold
   
   
2. Disengage the wiring harness connector from the IAC valve.
3. Remove the two retaining screws, then remove the IAC valve and discard the old gasket. To install: When installing the valve, always discard the old gasket and install it using a new one
   
   
4. Clean the IAC valve mounting surface on the throttle body of old gasket material.
5. Using a new gasket, position the IAC valve on the throttle body. Install and tighten the retaining screws to 71-106 inch lbs. (8-12 Nm).
6. Attach the wiring harness connector to the IAC valve.
7. Connect the negative battery cable.

you need to clean your idle air control valve ( or replace it) Spray carb cleaner does a nice job of cleaning it.

This tutorial is from autozone.com

OPERATION

The Idle Air Control (IAC) is a bi-directional motor driven by two coils. The purpose of the IAC valve is to control engine idle speed, while preventing stalls due to changes in the engine load. The IAC valve, mounted in the throttle body, controls bypass air around the throttle plate. The PCM controls engine idle speed by adjusting the position of the IAC motor pintle. The PCM pulses current to the IAC coils in small steps (counts) to extend the pintle into a passage in the throttle body to decrease air flow. The PCM reverses the current pulses to retract the pintle, increasing air flow. This method allows highly accurate control of idle speed and quick response to changes in engine load. If RPM is too low, the PCM will retract the IAC pintle, resulting in more air being bypassed around the throttle plate to increase RPM. If the RPM is too high, the PCM will extend the IAC pintle, allowing less air to be bypassed around the throttle plate, decreasing RPM.

Fig. Typical Idle Air Control (IAC) valve components
During idle, the proper position of the of the IAC pintle is calculated by the PCM based on the battery voltage, coolant temperature, engine load and engine RPM. If the RPM drops below a specified value, and the throttle plate is closed (TP sensor voltage is between 0.20-0.74), the PCM senses a near stall condition. The PCM will then calculate a new IAC pintle position to prevent stalls.
If the IAC valve is disconnected and reconnected with the engine running, the idle RPM will be wrong. In this case, the IAC has to be reset. The IAC resets when the ignition switch is cycled ON and then OFF . When servicing the IAC, it should be disconnected or connected with the ignition switch OFF in order to keep from having to reset the IAC valve.
The position of the IAC pintle affects engine start up and the idle characteristics of the vehicle. If the IAC pintle is fully open, too much air will be allowed into the manifold. This results in high idle speed, along with possible hard starting and a lean air/fuel ratio. A Diagnostic Trouble Code (DTC) may set. If the IAC pintle is stuck closed, too little air will be allowed in the manifold. This results in a low idle speed, along with hard starting and a rich air/fuel ratio. Again, a Diagnostic Trouble Code (DTC) may set. If the IAC pintle is stuck part way open, the idle may be high or low and will not respond to changes in engine load.

TESTING

As with most all engine control sensors used in your vehicle, a thorough and proper test can only be performed by a qualified technician using a scan tool to read the data stream from the PCM. There are a few items a non-professional should check before taking the vehicle to a qualified technician for diagnosis and repair.

Check for a poor connection at the PCM or IAC motor. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection. Inspect for a damaged wiring harness, especially if heavy work has recently been performed (intake manifold removal, engine removal, etc.) where the throttle body has been disturbed. Inspect for a restricted air intake system. Check for a possible collapsed air intake duct, restricted air filter element or foreign objects blocking the air intake system. Inspect the throttle body. Check for objects blocking the IAC passage or throttle bore. Excessive deposits, especially on high-mileage engines, can build up in the IAC passage and on the IAC pintle. Excessive deposits can also build up on the throttle plate, so check for a sticking throttle plate. Check for vacuum leaks such as disconnected hoses, leaks at the EGR valve and EGR pipe to the intake manifold, leaks at the throttle body, faulty or incorrectly installed PCV valve, leaks at the intake manifold brake booster hose connection, etc.

REMOVAL & INSTALLATION

1. Disconnect the negative battery cable.
2. Detach the electrical connector from the IAC valve.
3. Remove the 2 attaching screws and remove the IAC valve from the engine. Remove the O-ring from the housing.

To install:

Fig. The Idle Air Control (IAC) valve is mounted on the throttle body-3.8L (VIN K) engine shown, others similar

NOTE Before installing a new IAC valve, measure the distance that the valve is extended. The measurement should be made from the motor housing to the end of the valve cone (pintle). The distance should be no greater than 1 1 / 8 inch (28mm). If the pintle is extended too far, adjustment is required, otherwise damage may occur when the IAC valve is installed. Adjust the IAC valve by compressing the pintle to achieve the correct length.

1. Use a new O-ring, install the IAC valve and tighten the retaining screws to 18 inch lbs. (2 Nm).
2. Attach the electrical connector.
3. Connect the negative battery cable.
4. The PCM will reset the IAC valve the next time the ignition switch is turned ON and then OFF .
5. Start the engine and allow to warm to operating temperature to check idle quality.

High idle
Changed IAC still the same, shown on scanner IAC 50-60 %, if it set to 40% the Idle is ok. What cause the PCM to set IAC too high? Is any one know?

Hi there,

Well please follow the below link to check out the position of idle valve -

http://www.freeengineinfo.com/idle-air-control-valve-replacement.htm

The Idle Air Control (IAC) valve controls the engine idle speed and dashpot functions. The valve is located on the side of the throttle body. This valve allows the necessary amount of air, as determined by the Powertrain Control Module (PCM) and controlled by a duty cycle signal, to bypass the throttle plate in order to maintain the proper idle speed.

TESTING
Turn the ignition switch to the OFF position.
Disengage the wiring harness connector from the IAC valve .
Using an ohmmeter, measure the resistance between the terminals of the valve.

NOTE: Due to the diode in the solenoid, place the ohmmeter positive lead on the VPWR terminal and the negative lead on the ISC terminal.
If the resistance is not 7–13 ohms, replace the IAC valve.

The following symptoms can be caused by a faulty IAC due to loose connections, bad grounds, high resistance in the circuit, or opens in the circuit.
 
REMOVAL & INSTALLATION
Disconnect the negative battery cable.
Disengage the wiring harness connector from the IAC valve.
Remove the two retaining screws, then remove the IAC valve and discard the old gasket.

To install:
Clean the IAC valve mounting surface on the throttle body of old gasket material.
Using a new gasket, position the IAC valve on the throttle body. Install and tighten the retaining screws to 71–106 inch lbs. (8–12 Nm).
Attach the wiring harness connector to the IAC valve.
Connect the negative battery cable.


Good Luck!!

Thanks

The idle speed on this vehicle is controlled by the engine computer. If it seems to be idling high, the idle air control valve (IAC) may be stuck or faulty. This can sometimes be corrected by removing the IAC and cleaning carbon deposits out of it with carburetor cleaner. Some sensors can also cause a high idle, such as air temperature sensors or throttle position sensors. If everything else seems to be OK, however, the IAC is the best bet.

Operation

The Idle Air Control (IAC) valve adjusts the engine idle speed. The valve is located on the side of the throttle body. The valve is controlled by a duty cycle signal from the PCM and allows air to bypass the throttle plate in order to maintain the proper idle speed. Do NOT attempt to clean the IAC valve. Carburetor tune-up cleaners or any type of solvent cleaners will damage the internal components of the valve.
The Idle Air Control (IAC) valve adjusts the engine idle speed. The valve is located on the throttle body. The valve is controlled by a duty cycle signal from the PCM and allows air to bypass the throttle plate in order to maintain the proper idle speed.
Removal & Installation

1. Disconnect the negative battery cable.
2. Detach the IAC solenoid connector.
3. Remove the two retaining bolts and remove the IAC solenoid and gasket from the throttle body.
4. Installation is the reverse of the removal procedure. Use a new gasket and tighten the retaining bolts to 71-97 inch lbs. (8-11 Nm).