[Diy_efi] Air leak through the allen key adjuster - K-Jetronic

[urq]

... that could explain it ... updraft is the system the Audi uses ... and, 
as I posted last night there are no worries about messing up the mixture on 
the '89 Audi turbo that started this thread.

I did want to point out one slight misstatement in the message ... one of 
the amazing things to me about the CIS system is how it is designed to work 
with constant pressure in the metered fuel part of the system ... so the 
comment about the CO adjustment should read that it fine tunes the amount of 
fuel *flow* for a given amount of airflow sensor plate deflection.  The fuel 
pressure to the injectors is basically constant.  Bosch makes some very good 
pamphlets describing each of the various *-tronic systems, anyone interested 
in them can get them from Bosch.  I think the Bosch Automotive Handbook has 
a good description of this as well ... although I rarely refer to it any 
more, I still carry around my copy of that book ... just in case ... ;-)

On the '89 Audi 200 (US model) the mixture is primarily controlled by the 
control pressure regulator, which is bolted to the side of the engine block 
which can be modulated slightly with an OXS Frequency Valve, which the ECU 
controls based on the signal from the OXS.

Steve B
San Jose, CA (USA)
>
> No.  This is a fine tuning of the effect the airflow
> plate's deflection has on system fuel pressure, and
> thus delivered fuel quantity.  A decent analogy would
> be on an alpha-n EFI system, where calibrating the
> throttle position sensor has a similar effect on
> delivered fueling vs. air ingestion.
>
> I believe this is only true for the downdraft fuel
> meters; the updraft ones would not cause an air leak,
> and would only allow a small amount of unfiltered air
> into the intake system.