Open Air readings

Support forum for the Lambda Shield designed to connect Bosch LSU 4.9 wideband oxygen sensors to Arduino projects.
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elmo0104
Posts: 4
Joined: 24 Nov 2018 17:10

Open Air readings

Postby elmo0104 » 24 Nov 2018 17:20

Hi

I'm new here. I've made my own shield based on bylund information. It works but have some question- in open air a have a 20% content of oxygen. Most of resistors from schematic was 0.1% of precysion (not sure how to explain this value. I hope U anderstand).
Is this normal? I have bosch sensor but not new- can this be a problem?

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Christian_Bylund
Posts: 32
Joined: 07 Mar 2015 18:09

Re: Open Air readings

Postby Christian_Bylund » 24 Nov 2018 23:15

Hi elmo0104,

If you are reading around 20% in air you are close enough for any automotive readings. What calibration value are you reading, when the CJ125 is in calibration mode?

The reading of the sensor is depending on many factors, temperature of the cell, supply voltage of the CJ125, ADC voltage reference, ground plane interference, EMC, tolerances in components, the list goes long once you start to think about it. Our schematic describes an education approach on how to use the CJ125 controller for the Arduino.

I should also point out that the oxygen level calculation described by Bosch and used in our code is very much simplified. Our code is now designed to use a lookup table for the lambda, which is very accurate from a software conversion point of view. So to summarise, very good for measuring exhaust gases. Less accurate in measuring very lean gases such as air.

I hope this answers your question.
Best Regards,
Christian Bylund
Bylund Automotive AB

elmo0104
Posts: 4
Joined: 24 Nov 2018 17:10

Re: Open Air readings

Postby elmo0104 » 25 Nov 2018 12:27

Thank you!

The calibration readings are 176-177. Fiew firsts readings of o2 content after device reset are 20,58 ; 20,20 ; 20,00; 19,60 ; 19,80. and then is oscilating around 20%. My goal is to measure O2 content 1-5% . Will it be acurate enough for this range of o2 content?

I have another question about your app for display lambda and o2 content. It was working when I was using the "Lambda App" arduino software. Then when I load the code from GitHub to arduino it is not working byt now I can read o2 content from adruino IDE. Is it normal? What kind of data should be sent to PC by USB to use your PC "Lambda app"?

Regards
Peter

EDIT:

https://photos.app.goo.gl/VDGjrm9tUqvxEev36

It is the oil burner

elmo0104
Posts: 4
Joined: 24 Nov 2018 17:10

Re: Open Air readings

Postby elmo0104 » 29 Nov 2018 11:41

I have tryed fiew different condition lambda sensors and the calibration values are the same on each . I have got:

UA_Optimal : 305
UR_Optimal : 177


Each sensor shows different O2 content at air and at exhaust pipe in my oil burner. I'm operating at 3-4% O2 content. Is it normal ? I have bought brand new sensor and will give it a try when arrive.

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Christian_Bylund
Posts: 32
Joined: 07 Mar 2015 18:09

Re: Open Air readings

Postby Christian_Bylund » 29 Nov 2018 22:44

Best Regards,
Christian Bylund
Bylund Automotive AB

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Christian_Bylund
Posts: 32
Joined: 07 Mar 2015 18:09

Re: Open Air readings

Postby Christian_Bylund » 04 Dec 2018 21:37

Best Regards,
Christian Bylund
Bylund Automotive AB