Right values for Lambda

Support forum for the Lambda Shield designed to connect Bosch LSU 4.9 wideband oxygen sensors to Arduino projects.
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Stevo
Posts: 3
Joined: 18 Apr 2018 12:58

Right values for Lambda

Post by Stevo » 18 Apr 2018 13:00

Hello,

I'm meassuring on a 2-stoke scooter racing engine.
What should be the right values if the sensor is in open air? At the moment i get 1,8 lambda +-
When meassuring in exhaust i meassure 1,4 +- so it should be a bit lean. When i give more fuel it gives me 1,5 +- so what is going wrong?

Thank you!

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Christian_Bylund
Posts: 255
Joined: 07 Mar 2015 18:09

Re: Right values for Lambda

Post by Christian_Bylund » 18 Apr 2018 21:19

Stevo wrote: I'm meassuring on a 2-stoke scooter racing engine.
What should be the right values if the sensor is in open air? At the moment i get 1,8 lambda +-
When meassuring in exhaust i meassure 1,4 +- so it should be a bit lean. When i give more fuel it gives me 1,5 +- so what is going wrong?
Hi Stevo,

When measuring a clean sensor in air running at the correct temperature you should read an oxygen level above 20%. Even if you have the sensor in air and it has soot on it you might get a wrongful read. Try cleaning the sensor before you do an air read.

Inside an exhaust system when the engine is off, it will always pick up unburnt fuel and display lean lambda values.

Regarding your results, before commenting anything about it I would need to know how you perform your measurements. Are you measuring the same load at the same speed i.e working point?

Image
Above is an example of how the lambda can differ between speeds at full load.

Make sure to keep an eye on temperatures when tuning 2-stroke!

Thank you.
Best Regards,
Christian Bylund
Bylund Automotive AB

Stevo
Posts: 3
Joined: 18 Apr 2018 12:58

Re: Right values for Lambda

Post by Stevo » 23 Apr 2018 21:47

Thank you for the reply! As i found strange values, i ordered a new (real Bosch) sensor and now values are ok!
The other sensor was a replica i gues (also new) but quality was bad... So problem is solved! I have another question about a 0-5v output to connect it with our bench software so we can read the values... I open a new topic for it.

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Christian_Bylund
Posts: 255
Joined: 07 Mar 2015 18:09

Re: Right values for Lambda

Post by Christian_Bylund » 23 Apr 2018 22:53

Stevo wrote:Thank you for the reply! As i found strange values, i ordered a new (real Bosch) sensor and now values are ok!
The other sensor was a replica i gues (also new) but quality was bad... So problem is solved!
Great to hear you got it all up and running with the proper sensor!
Best Regards,
Christian Bylund
Bylund Automotive AB

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