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DonE DonE is offline
Wo ist die Rennstrecke?
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Join Date: Mar 2004
Location: Brooks, GA
Posts: 1,211
Originally Posted by hobieboy View Post
It is my understanding that one of the "side benefit" of CIS is self-altitude adjusting... Depending how much air (mass) is drawn through the throttle plate (barn door), corresponding amount of fuel will be added. So, it there's less air, because of heat, less throttle application, less air density because of barometric/humidity changes, etc., the plate will be pushed open less, hence less fuel.
I heard that....

When fine tuning my CIS car, I had to tune it twice per year - summer (less fuel) and winter (more fuel). The temp at which I had to change the WUR pressures was about 55F or so. Below that, I needed to decrease WUR pressures to increase fuel flow. Also, didn't Porsche make a WUR that took pressure (aka, air density) into account in later CIS models? My 79 model did not.

So, although the CIS "barn door" generally works well, it is NOT a mass air flow sensor.
Old 08-15-2007, 06:30 PM
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