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Video Petrol Injection 1
Video Petrol Injection 2
Video Petrol Injection 3
Video Petrol Injection 4
Video Petrol Injection 5
Video B-Dir. Combustion
Video Dir. Petrol Injection 1
Video Dir. Petrol Injection 2
Video Dir. Petrol Injection 3
Video Dir. Petrol Injection 4
Video Dir. Petrol Injection 5
Video Petrol Injection Kugelf.
Video Homog. Working
Video Stratified-charge Oper.
Video Fuel Distrib.
Video Induction System
Video Petrol Injection Signal 1
Video Petrol Injection Signal 2
Video Idle Speed Device
Video Mass Air Flow Sensor 1
Video Mass Air Flow Sensor 2
Video Mass Air Flow Sensor 3
Video System Press. Reg. 1
Video System Press. Reg. 2
Video Injection Valve
Video Ind. Pulse Generator
Video Single Point Injection 1
Video Single Point Injection 2
Video Single Point Injection 3
Video Single Point Injection 4
Video Unregistrated Air
Video Lambda Sensor 1
Video Lambda Sensor 2
Video Lambda Sensor 3
Video Lambda Sensor 4
Video Lambda Sensor 5
Video Thermo Time Switch
Video Side-channel Pump
Video Peripheral Pump

Video First Fuel Pump
Video Petrol Injection Pump
Video D-Jetronic (MPI)
Video K-jetronic
Video KE-jetronic
Video KE-Jetroncic - Test, Diagn.
Video L-jetronic
Video LE-jetronic
Video LE-motronic
Video LH-jetronic
Video Vol. Air Flow Sensor
Video Idle Speed Device
Video Aux. Air Valve
Video Thermo Time Switch
Video Roller Vane Pump

Video Petrol injection 1
Video Petrol injection 2

          A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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

First start with a new auxiliary fan               Top of page               Index
2001-2015 Copyright programs, texts, animations, pictures: H. Huppertz - E-Mail
Translator: Don Leslie - Email:

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