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Discussion in 'Technical Q&A' started by pnorman, Feb 8, 2004.
Can a bad thermotime switch create a starting problem because it controls the warm up regulator?
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What year/model/version F? (Your Profile is blank!)
Do you mean the thermo-time switch or a coolant thermoswitch?
(However, my guess would be "NO" either way -- IIRC the K-Jet warm-up regulator is an open-loop device not relying on other sensor input, but give more information.)
I'm sorry, I meant the thermotime switch. 82 Mondial 2v 308...Patrick
IIRC there is no functional association between the the warm-up regulator and the thermo-time switch (which controls how long the cold-start injector opens during cold starter cranking) on a K-Jet system.
What is your symptom -- no cold start and no hot start even though starter cranks well? You've verified ignition spark?
I have spark and fuel. If I don't unplug the cold start injector, my throttle body floods. What give the warm up regulator its signal?
The K-Jet warm-up regulator is strictly an open-loop device -- it has an internal +12V heater, and it absorbs heat directly from the engine -- so it doesn't use any external electrical "signals" to actively control its behavior.
Do an internet search on "K-Jetronic Warm-up regulator" you should get many good references like:
http://www.320i.com/kjetronic.htm (and it shows three other reference links)
I'd also recommend that you get the Aird Bosch CIS book, or, if you want more technical (but not as introductory) meat, the Probst Bosch CIS book from Amazon.
With regard to the cold start injector, if you measure the voltage at the connector, it should go +12V for something like 1~8 seconds only during cold starter cranking -- if it doesn't (like it goes +12V during hot cranking), then you could have a problem with the thermo-time switch.