cold engine driveability - modify water temp resistance?

[Aribert_Neumann at magna.on.ca]

I have mated a Bosch M1.5 EFI from a 2.0L GME (Opel) engine to a 2.3L formerly
carb'ed engine.  Much to my pleasant surprise it works surprisingly well with
out any changes to any sensors or to changing any look-up tables in the ECU (I
am not knowledgeable in that area).  THe engine idles good when cold but will
die if the throttle is lifted abruptly (i.e. lifting off of the throttle when
approaching a red light - I have gotten good at slipping the clutch just before
the vehicle comes to a stop to restart the engine).   At an outside ambient temp
of 50 deg F this condition last for about 3+ miles in city driving.   THe temp
sensor (Bosch P/N 0 280 130 026, with addition numbers of 050 and 026 on the hex
flats) appears to have a very similar resistance range to the GM (North America)
sensors when comparing my Bosch sensor to the values posted in the archives.
Can I add an additional resistor in line (sensor has two contacts - I assume the
ECU sends a 5.0v signal thru the sensor - have not confirmed yet) between the
water temp sensor and the ECU?  I have seen posting in the archives make mention
of adding resistors in parallel or in series but not of mentioning specific
resistor values used.

FWIW, I added a Cyberdyne A/F gage to check the A/F and compare with my plug
readings since I am running a system designed for 2.0L on a 2.3L engine.  If I
were able to take an average of the gage display range I suspect / perceive that
the engine is slightly lean on average.  If I shift the water temp resistance to
give an indicated cooler temp to the ECU can I expect it to enrichen the A/F a
bit.  Other options that I am considering to enrichen the A/F is to replace the
water thermostat with a lower (180 deg F) temp unit  (currently I am running a
195 deg F unit - closest in value to the thermostat used in the GME engine.  A
more expensive alternative would be to replace the injectors with a higher flow
rated unit.    I understand that changing the ECU state tables is a more elegant
solution but that is not a viable option based on my lack of knowledge and the
ECU in the vehicle is the only one that I have and I would need to source a
spare from Europe if my original were to become non-functional.

patiently waiting in digest mode for any direction / suggestions


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