What is a EGR valve & IAC valve & where are they located?

Vacuum leak , IAC valve - idle air control , Go to your tube an check out videos on checking for vacuum leaks an how to test IAC valve an cleaning throttle plate an IAC - air passages ! Eva codes ? what code # ?

4 cylinder model the EGR valve is located between 2 & 3 cylinder on intake manifold and between Carb and valve cover it has a diaphragm cover about 3 inches round and one vacuum hose 2 bolts holds it to the intake. V-6 models EGR valve is located on drivers side of engine just behind carb and about the same size and roundness and one hose two bolts.

1. Install a tachometer on the engine, following the manufacturer's instructions.
2. Detach the engine wiring harness connector from the Idle Air Control (IAC) solenoid.
3. Disconnect and plug the vacuum supply hose from the EGR valve.
4. Start the engine, then apply the parking brake, block the rear wheels and position the transmission in Neutral.
5. Observe and note the idle speed.
   

If the engine will not idle with the IAC solenoid disconnected, provide an air bypass to the engine by slightly opening the throttle plate or by creating an intake vacuum leak. Do not allow the idle speed to exceed typical idle rpm.
Using a hand-held vacuum pump, slowly apply 5-10 in. Hg (17-34 kPa) of vacuum to the EGR valve nipple.

1. If the idle speed drops more than 100 rpm with the vacuum applied and returns to normal after the vacuum is removed, the EGR valve is OK.
2. If the idle speed does not drop more than 100 rpm with the vacuum applied and return to normal after the vacuum is removed, inspect the EGR valve for a blockage; clean it if a blockage is found. Replace the EGR valve if no blockage is found, or if cleaning the valve does not remedy the malfunction.

EGR Valve Removal & Install
3.0L OHV (2 valve) and 3.4L SHO engines



Fig. : EGR mounting-3.0L OHV (2 valve) engine



Fig. : EGR mounting-3.4L (SHO) engine



Fig. : Remove the two retaining bolts and...



Fig.: ... remove the valve from the intake manifold



Fig.: Thoroughly clean the mating surfaces of the manifold and the EGR valve (if being reused)

1. Disconnect the negative battery cable.
2. Remove the vacuum hose from the EGR valve.
3. Using a 22mm wrench or crowfoot, disconnect the EGR valve-to-exhaust manifold tube from the EGR valve.
4. Remove the EGR valve mounting fasteners, then separate the valve from the intake manifold.
5. Remove and discard the old EGR valve gasket, and clean the gasket mating surfaces on the valve and the intake manifold.
   

To install:

1. Install the EGR valve, along with a new gasket, on the upper intake manifold, then install and tighten the mounting bolts to 15-22 ft. lbs. (20-30 Nm).
2. Connect the EGR valve-to-exhaust manifold tube to the valve, then tighten the tube nut to 26-47 ft. lbs. (35-65 Nm).
3. Connect the vacuum hose to the EGR valve.
4. Connect the negative battery cable.

3.0L OHC (4 valve)



Fig. : EGR mounting-3.0L OHC (4 valve) engine

1. Disconnect the negative battery cable.
2. Remove the vacuum hose from the EGR valve.
3. Remove the two EGR tube-to-EGR valve retaining nuts.
4. Remove the EGR valve mounting fasteners, then separate the valve from the intake manifold.
5. Remove and discard the old EGR valve gasket, and clean the gasket mating surfaces on the valve and the intake manifold.
   

To install:

1. Install the EGR valve, along with a new gasket, on the upper intake manifold, then install and tighten the mounting bolts to 15-22 ft. lbs. (20-30 Nm).
2. Connect the EGR valve-to-EGR tube, then tighten the retaining nuts.
3. Connect the vacuum hose to the EGR valve.
4. Connect the negative battery cable.

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Idle Air Control Valve

• OPERATION
• TESTING
• REMOVAL & INSTALLATION

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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.

TESTING

See Figure 1

Fig. Fig. 1: The IAC can be monitored with an appropriate and Data-stream capable scan tool

1. Turn the ignition switch to the OFF position.
2. Disconnect the wiring harness from the IAC valve.
3. Measure the resistance between the terminals of the valve.

Due to the diode in the solenoid, place the ohmmeter positive lead on the VPWR terminal and the negative lead on the ISC terminal.

1. Resistance should be 6-13 ohms.
2. If resistance is not within specification, the valve may be faulty.

REMOVAL & INSTALLATION

1. Disconnect the negative battery cable.
2. Detach the IAC solenoid connector.
3. Remove the 2 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).

If scraping is necessary to remove old gasket material, be careful not to damage the IAC solenoid or the throttle body gasket surfaces or drop material into the throttle body.
See Figure 2

Fig. Fig. 2: IAC solenoid location-4.6L engine

you can try cleaning the IAC valve(idle air control) & mass air flow
a good injector cleaner (slick50)in the tank

P0401 - Insufficient EGR Flow
EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.

Symptoms: You may notice drivability problems such as pinging (a.k.a. pre-ignition knock) when the engine is under load or the vehicle is at higher speeds. There may also be other symptoms.

Causes: A code P0401 most likely means one or more of the following has happened:
The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
There is a blockage in the EGR (tube), most likely carbon buildup
The EGR valve is faulty
The EGR valve may not be opening due to a lack of vaccuum

Possible Solutions: In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit:
Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
Clean out the EGR valve and/or tubing to remove deposits
Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
Replace the DPFE sensor (with a good quality / OEM one)
Replace the EGR valve


P1504 - Intake Air Control circuit malfunction
The problem likely is a defective IAC valve. You can check the valve by unplugging the IAC and checking the resistance between the 2 wiring pins, should be between 6 to 13 ohms. Also check the resistance from the pins to the IAC body, meter should read open circuit, any resistance reading from the pins to the IAC body indicates a short. I doubt that there is a problem in the wiring harness or PCM, it is possible and should not be ruled out, although it is not seen often.

EGR Valve Testing

1. Install a tachometer on the engine, following the manufacturer's instructions.
2. Detach the engine wiring harness connector from the Idle Air Control (IAC) solenoid.
3. Disconnect and plug the vacuum supply hose from the EGR valve.
4. Start the engine, then apply the parking brake, block the rear wheels and position the transmission in Neutral.
5. Observe and note the idle speed.
   

If the engine will not idle with the IAC solenoid disconnected, provide an air bypass to the engine by slightly opening the throttle plate or by creating an intake vacuum leak. Do not allow the idle speed to exceed typical idle rpm.
Using a hand-held vacuum pump, slowly apply 5-10 in. Hg (17-34 kPa) of vacuum to the EGR valve nipple.

1. If the idle speed drops more than 100 rpm with the vacuum applied and returns to normal after the vacuum is removed, the EGR valve is OK.
2. If the idle speed does not drop more than 100 rpm with the vacuum applied and return to normal after the vacuum is removed, inspect the EGR valve for a blockage; clean it if a blockage is found. Replace the EGR valve if no blockage is found, or if cleaning the valve does not remedy the malfunction.

EGR Valve Removal & Install
3.0L OHV (2 valve) and 3.4L SHO engines



Fig. : EGR mounting-3.0L OHV (2 valve) engine



Fig. : EGR mounting-3.4L (SHO) engine



Fig. : Remove the two retaining bolts and...



Fig.: ... remove the valve from the intake manifold



Fig.: Thoroughly clean the mating surfaces of the manifold and the EGR valve (if being reused)

1. Disconnect the negative battery cable.
2. Remove the vacuum hose from the EGR valve.
3. Using a 22mm wrench or crowfoot, disconnect the EGR valve-to-exhaust manifold tube from the EGR valve.
4. Remove the EGR valve mounting fasteners, then separate the valve from the intake manifold.
5. Remove and discard the old EGR valve gasket, and clean the gasket mating surfaces on the valve and the intake manifold.
   

To install:

1. Install the EGR valve, along with a new gasket, on the upper intake manifold, then install and tighten the mounting bolts to 15-22 ft. lbs. (20-30 Nm).
2. Connect the EGR valve-to-exhaust manifold tube to the valve, then tighten the tube nut to 26-47 ft. lbs. (35-65 Nm).
3. Connect the vacuum hose to the EGR valve.
4. Connect the negative battery cable.

3.0L OHC (4 valve)



Fig. : EGR mounting-3.0L OHC (4 valve) engine

1. Disconnect the negative battery cable.
2. Remove the vacuum hose from the EGR valve.
3. Remove the two EGR tube-to-EGR valve retaining nuts.
4. Remove the EGR valve mounting fasteners, then separate the valve from the intake manifold.
5. Remove and discard the old EGR valve gasket, and clean the gasket mating surfaces on the valve and the intake manifold.
   

To install:

1. Install the EGR valve, along with a new gasket, on the upper intake manifold, then install and tighten the mounting bolts to 15-22 ft. lbs. (20-30 Nm).
2. Connect the EGR valve-to-EGR tube, then tighten the retaining nuts.
3. Connect the vacuum hose to the EGR valve.
4. Connect the negative battery cable.

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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?

The IAC vavle is located behind the EGR valve on the driver side of the motor. You will disconnect 2 hoses and unplug the wire harness from the system. The unit will come right out. Just make sure that the hoses you take off go back in the same place. Also make sure that you have the negative battery wire disconnected. I had this same issue on my 2001 Escape, had to replace both the EGR and IAC so check both carefully.

EGR(top)IAC(3bottom views).EGR will be on the intake,IAC will be on the throttle body.