motronic 173

Discuss Bosch (Porsche, BMW, Volvo, etc) tuning topics here. Request definitions, discuss parameters, etc.

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marcone
Posts: 18
Joined: Thu Dec 20, 2012 10:50 am

motronic 173

Post by marcone »

Hi I have a Bmw e30 2.5 with emulation trying to get the idle fuelling dialled in. I am finding that the cts enrichment isn't measuring correctly. It seems to hit max temp in the xdf before it has reached engine running temp. How can I adjust the settings as the only way to get idle fuelling correct is with a zero in the max temp in the cts but on cold start it runs really lean as no additional fuel is being added. But if I do not zero this box say to 20 then it wont let me pull the idle afr down as it is adding fuel.

Tried to explain best I can. I have m20b25 ecu 173 sw 705 xdf.

Having a look it almost seems it is reading in Fahrenheit but displaying in celcius.
Hairyscreech
Posts: 196
Joined: Tue Jun 20, 2017 3:19 am

Post by Hairyscreech »

Sorry for the pretty late reply, work commitments meant a slightly abandoned project for the summer/autumn.

Check your CTS sensor against the measured values for the M20 and M50 sensors in the excel file in the dropbox in the M3.3.1 thread.
They are very carefully measured true resistances for OEM and aftermarket sensors.

After that you behavior is fairly normal.
I found mine got to the max temperature around 50-60 degrees coolant temp.

The only way to change the steps is to firstly understand how the maps are formatted and how the axis values are counted backwards from 255.
Then to change the values manually in the binary to start at a higher temperature and keep the same lower temperatures.

The M3.3.1 thread and the associated excel document with the highlighted BINs/code show how to do all of that but it your struggling then post back up here and I will take a look if you post the BIN.

p.s. the 173 works nearly exactly like the M3.x ecus in this regard, table formats are the same.
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