Rough idle problem

[Jens Knickmeyer]

Hi all!

I have a problem with my VW Polo-G40 using the Digifant1 ECU,
an intermittant fuel injection and ignition system.
When I start the cold engine it runs fine. After a few minutes
when it heats up, the idle rpm is reduced. When this happens,
the idle gets rough. On cold days this is rather extreme, one
could think the engine would die. When warmed up there is no
problem. The valve which lets in additional air when the engine
is cold (sorry, do not know the English word) works mechanically 
with a bimetal which is heated by electric current. This current
is not stabilized or controlled by the ECU. Could it be that
it opens too early, is this a known bug for such parts?
I checked the temp. sens. by maesuring resistance and it looked
ok.
What about the inj. valves, I heard on an intermittant system
they need some cleaning from time to time. How can I do this and
what inj. cleaners are best?

Any suggestions welcome,

Jens.
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           Jens Knickmeyer
Technische Universitaet Braunschweig
         Mikroporzessorlabor
 38106 Braunschweig near Wolfsburg
       knick at ibr.cs.tu-bs.de
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