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Старый 28.04.2021, 17:13   #2
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Hello Jean-Christophe
First I understand that the lambda is mandatory for the first setup, but mine is badly placed in my opinion. I put it in the silencer (I soldered it by myself, there is no OEM place for a lambda in this exhaust, my lambda only serves for a dashboard gauge, since my ECU (Dijijet) doesn't take this information into account), so its signal is not very accurate I think (it goes regularly from very lean to very rich, but rarely between both, but maybe it's because of a worn VAF...).
Yes - the oxygen sensor is a mandatory thing for tune the mixture properly.
Without it you will get a very bad results and very big fuel consumption.
Here ir video on russian about wrong installation of oxygen sensor
You can try to enable autotranslation of subtitles - hope that about 70-80% will be clear for you. In a short words if the oxygen sensore installed in a bad place - it will give a very slow response and it will be difficult to tune the mixture properly.

Is it possible to use the converter without it or do I absolutely need to wire it to the converter despite the relative inaccuracy of the signal?
You need to connect the oxygen sensor signal to the converter, because inaccurate signal is better then nothing at all.

If it needs to be connected to the converter, is it possible to do it in parallel with my dashboard gauge or do I need to connect the converter alone?
If your oxygen sensor is a narrow band zirconia type then you can connect it in parallel- it will work fine.

Second, I have questions about the wiring.
I have +5V between 1-4 on my VAF and +4,6V between 1-2 (see https://www.dropbox.com/s/2l0ecgjhpf...itled.jpg?dl=0 for a caption of VW workshop manual). Should connection 1 of the car harness go to "JP1.2-Ref. Voltage In" Converter connection?
To which harness-debimeter connection should "8-Converter out" be connected?
Are the MAF converters connections the same between the siemens model you recommend and the ones from VAG brands? I have this one (for VW Passat) for the moment : https://fr.aliexpress.com/item/33033...27426c37I4ObrN, or what would be the way to know the right connection to the converter?
What is the 5-TPS or VAF in connection for? Is it meant to connect the two devices in serial and compare the two signals?
Accordingly to first scheme your airflowmeter has next pinout:
1- Air temp sensor
2-Signal output
3-reference voltage 5v
Now put one proble of multimeter on engine and with other probe check voltage on all contacts and let us know the result.

if ref voltage trully 5v? then you dont need to connect it to the converter - just set the jumper on the converter to the" motronic" position - in this case the converter will use internal 5V as reference voltage.
Output 8 of the converter must be connected to the wire wich goes to pin 2 of genuine airflowmeter
It will be better to find the pinout of this siemens in a corresponding audi workshop manuals.
You right TPS or VAF input was used in first firmwares to compare both signals from different airflowmeters installed in series, but this method gave a bad results so we decided not to use it.
In the next firmwares we use this input to switching between tables or for selecting different reference values of oxygen sensor for tuning algorythm.
Now you dont need to use it at all.

I have made a draft of the wiring plan which you can find here if needed for verification and comments => https://www.dropbox.com/s/wqn86sofvr...p1%29.pdf?dl=0
This is wrong.
1. You should find the signal ground of genuine airflowmeter and connect ground of the converter and new airflowmeter to that wire, otherwise you will get a lot of noise in signals.
2. During tuning process connect supply of the converter and new airflowmter directly to the battery + via a 5A fuse - this will make tuning process very simple, beacuse the software will not loose connection with the converter in this case.
After all tunings will be done , you will connect reconnect the supply wire to some ignition switch supply.

At this moment i higly recommend you not install new maf, but just install the converter in series with a signal of genuine vaf. You will need to connect ground, supply, oxygen sensor signal, cut signal wite from airflow meter and connect one part to MAF input and other part which goes to ECU to the " converter output"
Put in the converter 1:1 table and start engine.
Look and try how the correction an autotuning works, how it uses oxygen sensor etc. After you understand how all works - next you can place there a new maf.
Also you can make some logs of how your genuine airflometer and oxygen sensor works and post them here - i can check it and confirm is all ok or not.

Последний раз редактировалось Pin; 28.04.2021 в 17:28.
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