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| Brushy Mountain SAAB (1984 900 pass. side engine view) |
| The white arrow near the front of the engine points to the auxilliary air valve, which "steps up" the idle speed to about 1500 RPM when the engine is cold. It does this by allowing extra air to come past the throttle valve through its orifice. The orifice has a slit which gradually closes as the bimetal strip it is attached to heats up. Heating the bimetal is done by a small electric heating element (which is the reason for the electrical connector) and also by engine warmth. This begins to close the valve, slowly, from startup, and the valve is closed fully approximately 3-6 minutes after starting, depending on ambient temperatures. The valve has a two-wire (sheathed) electrical connector, and two approx. 1/2" diameter rubber air hoses connected to it which go back to throttle body. |
| Auxilliary Air Valve, CIS (K-Jetronic) 8V 900 only |
| TESTING: |
| The aux. air valve can be checked several ways. 1) Remove the two 1/2" rubber hoses which are either simply pushed onto or might be clamped onto the aux. air valve. Using a mirror or small flashlight positioned at one tube/hose connection, see if the valve is open. If you are experiencing a low idle at startup, the aux. air valve is most likely stuck closed. If you have an incurable high idle that will not go away, the valve could be stuck open, but read #3 below. Sometimes the valves can be freed up by spraying WD-40 in there and wiggling the orifice's slit back and forth with a small, flat screwdriver. 2) If the valve still won't open, replace it. 3) If the valve won't close, make sure the connector plug is supplying 12V with the ignition key turned to "on," using a voltmeter. If you don't have 12V, then suspect a wiring short. If you do have 12V, then the aux. air valve's internal heating element has gone bad. To make sure, connect an ohmmeter across the two terminals ON THE AUX. AIR VALVE. The reading should be about 40 ohms. If the reading is close to or is zero (0) ohms, then replace the aux. air valve. |
| DESCRIPTION: |
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| Shown above is the AAV (auxilliary air valve) with air hoses removed. The orifice is visible with a small slit inside. Slit width varies with temperature--the colder it is, the wider the slit, the higher the cold idle speed.This view is from the passenger's side (USA) looking down into valve. |
| Above is a close-up of the auxilliary air valve on Saab 900 8V motors. It is just to the rear of the thermostat housing. (Warm-up fuel pressure regulator is seen at right.) View is from passenger's side (USA). |
| White arrow indicates location of auxiliary air valve. |