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Pierburg 1B2 electro choke

I posted this in uk.rec.cars.modifications but did not find an answer. Hope someone here will help.

I am trying to figure out the way elecro choke works in my '87 E30 BMW with Pierburg 1B2 carb. I have explanation for it but it is in German. Anyone speaks German? Hire:

Die elektrische Verschaltung der Startdeckelbeheizung beim 2B4 Vergaser:

Die Bimetallfeder (1) im Startdeckel (2) wird von zwei Heizelementen (5 und

6) beheizt. Das untere (5) ist bei eingeschalteter Zündung (symbolisiert durch den Schalter 4) in Betrieb. Das obere Heizelement (6) ist von der Stellung des Thermoschalters (3) abhängig. Dieser gibt den Stromweg erst ab 55C frei. Allerdings schaltet er anschließen erst wieder bei 15C ab, so daß die zweite Heizung während der warmen Jahreszeit - wenn die Temperaturen erst gar nicht so weit absinken - häufig gleich vom ersten morgendlichen Motorstart an mitheizt.

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Now I understand that in there are two heating elements in bi-metal housing, and that one is switched on when the ignition is on. What I do not understand when is the other one switched on ad when off.

I tested how it works on my car. With cold engine at ~5C (~40F) thermoswitch is switched off. After couple of minutes it is switched on (I do not knew at what temperature), and stays on at normal engine temperature.

I do not understand what is suppose tho happen at 15C and what at 55C. Can anyone help please?

Reply to
Yvan
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is handy.You've got two heating elements that warm the spring up, the first one starts warming the spring,which is cooled by the air, to give some delay when it's cold, the 2nd heaters switched by the thermoswitch so that you the choke switches off faster when you do a warm start, it doesn't switch on until the engines up to 55deg C & then it stays on till the temperature drops to 15degC.

Reply to
Duncanwood

I tried that, and BabelFish, but I could not make any sense of translation.

Thank you. That clears it up for the second heater. But now I have further question for the operation of the first one. What air cooles it? Air around bi-metal housing?

Reply to
Yvan

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