Idle control module - function/modify signal?

[Aribert_Neumann at magna.on.ca]

I am looking for info on the basic concept behind an idle control module as used
on a Bosch Motronic (specifically M1.5).  THis unit (about 1 in. cubed) has an
electical connector with 2 leads and 2 vac ports - one to the cannister the
other port on the intake manifold downstream of the throttle plate.  I am
looking for ways to modify the signal back to the ECU.  Since I am in North
America and the engine management system is off of an Opel/Vauhall, I am very
reluctant to split open the case to see what is inside due to the difficulty in
getting spares.

Background:  I have adapted the Motronic M1.5 system from a 2L GM Europe engine
onto a 2.3L Isuzu engine.  So far  the Isuzu vehicle has completed about 1500
uneventful miles since the conversion from the carb.  Only problem is the engine
will die when lifting off of the throttle for the first several minutes/ miles
of use.  Once the engine warms up then the idle is good.  I have upped the idle
by 100 rpm by adjusting the throttle plate stop and added an 1300 ohm resistor
in line from the water temp sender.  Both changes improved the condition but not
enough.   I do not have the skills to modify ECU codes.  Other suggestions?



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