The idle air control valve (idle air valve) maintains idle speed regardless of changes in engine load. If the idle speed drops below 750 rpm, the electric valve begins to supply some air bypassing the throttle valve, thereby increasing the speed. When they increase to 950 rpm, the valve closes, stopping the supply of additional air and reducing the idle speed.
Necessary
Multimeter. In its absence, an ammeter and an ohmmeter
Instructions
Step 1
Typically, power management systems have a separate idle speed control unit. The idle valve may have an adjusting screw. For the location of the idle speed control unit and the valve adjusting screw, see the repair manual for a particular car. New car models of recent years of production are not equipped with an idle valve adjustment.
Step 2
Before checking the two-wire idle valve, it is necessary to warm up the engine to operating temperature (60 degrees), turn off all electrical equipment, make sure that the throttle position sensor, oxygen sensor are in good working order, that there are no leaks in the exhaust system and in the vacuum system, and that the tachometer is connected correctly.
Step 3
Start the engine. A working idle valve should work continuously (vibrate and hum slightly). Then disconnect the electrical connector from the valve. The revs should rise to 2000 rpm.
Step 4
If the idle speed has not changed, take an ohmmeter and measure the resistance between the contacts of the valve under test. This value should vary from 9 to 10 ohms. Make sure that when the battery voltage is applied to the valve, it is tightly closed, and when the voltage is removed, it opens. If the idle valve does not have the required resistance or does not work correctly, then it is faulty and must be replaced.
Step 5
The control current is checked as follows. After disconnecting the electrical connector from the valve, connect one pin of the connector to the valve pin through a jumper, and the other through an ammeter (instrument range should be 0-1000 mA). When the engine is idling, the ammeter should show a current of 400-500 mA. Any other ammeter reading indicates the required idle valve adjustment. Please note that the ammeter can show a current strength of more than 500 mA if at least one of the conditions described in paragraph 2 is not met.
Step 6
If the ammeter shows no control current, the idle speed control unit should be returned for repair or replaced with a new one. By the way, the reason for the malfunction of this unit may be a malfunction of the electrical connector. In this case, replace the connector.
Step 7
If the car is equipped with a 3-wire idle valve, to check, follow the same steps as described in paragraphs 1-4, except for the following nuances. Measure the electrical resistance between the two end contacts. It should be 40 ohms. Then measure the resistance between the center and outer pins. It should be 20 ohms.
Step 8
Checking the control current of the three-wire valve is checked by measuring the voltage at the center pin. It should match the voltage of the battery. The voltage between the center and outer contacts should be 10 V.
