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 Engine Oil-Finder

Auxiliary Air Valve


Before control devices began to regulate the idling RPM, the first electronic- and mechanical fuel injection systems had to manage with the auxiliary air valve. It could only increase the idling RPM after the cold starting, and depending on the amount of time and the engine temperature, lower it again to the normal idling level. It could not e.g., react to the turning on of the air- conditioning and/or the engaging of the 'D' position of the automatic transmission.


The top picture shows an auxiliary air valve, at the top with an air-hose connection each on the left and on the right. One comes from somwhere between the air filter and the throttle valve, and the other can flow into somewhere between the throttle valve and the cylinder head. The aim is to bypass the throttle valve itself. At the bottom, one can see the electric connection, which through the ignition switch, has continuous plus (terminal 15). As one can partly see in the second picture, the air duct is open when the auxiliary air valve is cold. When the ignition is switched on, the bimetal spring is heated, it increases the pressure and keeps, for a warm-up period depending on the outside temperature, the bypass channel closed. Additional services are provided by the engine heat, for this reason, the auxiliary air valve is mounted in places where it can be reached by the engine heat. 02/11

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