Introduction and some questions

[Ti Kan]

Ben Doughney writes:
> What are the features of CIS-E compared to the standard CIS system? I 
> was trying to compare what I have got with some of the pictures on 
> Huw's webpage (http://www.humanspeakers.com/audi/cis-e.htm) but I am 
> still not 100% sure what I have.

The CIS fuel distributor bodies are usually painted black whereas CIS-E
are usually silver in color.  The CIS system uses a "control pressure
regulator" (also known as a "warm up regulator" for cold running enrichment.
This is a device that is mounted on the engine block, with two fuel lines
running from the fuel distributor to it, and an electrical plug for
a built-in heater.  CIS-E, on the other hand, does not use a CPR.
CIS-E has a "differential pressure regulator" mounted on the side of the
fuel distributor, it has an electrical plug on it from the ECU.  The
cold enrichment and dynamic fuel mixture is all controlled through this
device.

These are the main visually distinguishable differences.  There are
other small differences too.

> Can you see the computer from under the dash if it is CIS-E?

The original CIS did not have a "computer" or ECU.  It was all-mechanical.
When catalytic convertors were added in the late 70s (for the US market),
an ECU was also added to provide loop control, via a "frequency valve"
attached to the fuel distributor.

All CIS-E systems have an ECU, but uses the above-mentioned DPR for
mixture control instead of a frequency valve.

-Ti
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