How to measure a Bosch LSU 4.9 wideband lambda sensor

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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby arjen » Fri Sep 12, 2014 8:17 pm

Robski,

What's the point of asking questions when you already seem to know or don't want to hear the answers.
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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby Robski » Fri Sep 12, 2014 8:39 pm

or don't want to hear the answers

Eh ?
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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby brett nz » Fri Sep 19, 2014 4:11 am

Just a though, rather than needing a micro amp clamp why not just put a 100x coil in place and use normal clamp?
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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby Robski » Fri Sep 19, 2014 6:49 am

brett nz wrote:Just a though, rather than needing a micro amp clamp why not just put a 100x coil in place and use normal clamp?

hey Brett,

how you getting on with your tiepie ?

One of the reasons I don't use that method is access to the harness/O2 connector to attach breakout leads, I might make one up for next time I have the need to.
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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby Fat Freddy » Sun Sep 21, 2014 1:11 pm

Double post deleted.
Last edited by Fat Freddy on Sun Sep 28, 2014 12:55 am, edited 1 time in total.
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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby Fat Freddy » Sun Sep 21, 2014 1:12 pm

Nice work Kim.

Had a play with 4.9 lsu a couple of years ago on a 300tdi for kicks. I chose the 4.9 because of its wide operating "range from Lamda = 0.65 to air". Also plotted against EGT pre turbo using a K type thermocouple (poor accuracy in those early days but a good indication).

Interesting but not much diagnostic value in it though.

FF
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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby Steve Smith » Mon Sep 22, 2014 9:59 am

Hello FF, thanks for the attached image.

Very interesting looking at what you have monitored and the relationship between all the inputs.

Do you have the psdata file as I am intrigued by the units?

Did you utilise the custom probe settings for O2% level and PSI etc?

I think a test like this would be of real diagnostic value if we could ensure accuracy.

Take care......Steve
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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby Fat Freddy » Sun Sep 28, 2014 12:50 am

G'day Steve

Apologies for the late reply.

The capture was done using some electronics (a controller) and a bit of imagination. Not as cheap or as convenient as Kim's method. I posted the image as it shows the coverage of a lsu 4.9 and the values that occur in a mechanical diesel engine compared to what Kim is seeing on a modern diesel. I would like to do the same test on a modern diesel along side Kim's method. Time and a donor vehicle required though.

Do you have the psdata file as I am intrigued by the units?

Did you utilise the custom probe settings for O2% level and PSI etc?


I did use the custom probe settings. The psi values are the standard ones (almost :wink: )

The Lambda (L) values are taken from an output on the controller which is required to control and monitor pump current, as you know. The controller also has a data output so software can be used to monitor L or A/F ratio's. The output I used is separate from the data output and is user programmable. So I just programmed certain outputs for certain L values calculated from pump current (the values are then interpolated). This becomes an output from the controller. I then put the same value's in the custom probe interpolated again. Done. Sounds easier than what it was to figure out. :D
The Oxygen values are taken from a table that gives the info for given L values.

As for accuracy, that's hard to assess and part the reason I didn't follow through. In theory it should be accurate and it does seem to match the data output.
Also the output is a differential (noise reduction/accuracy) output and because I used all four channels I couldn't do a normal two channel/maths calculation for true output. So possible errors here. Of coarse the latest picoscope https://www.picoauto.com/automotive-oscilloscope.html can get round this problem I think. As I said, proving or disproving the figures became a hurdle.

Temp was calculated using a basic calculation plus an additive allowing for cold junction compensation, but didn't allow for the Curie point. In this application it appears to be to large an error which again (at that time), was hard to prove or disprove the accuracy. But..... in the last couple of months may have found a way to check accuracy by using an Ad595(?) www.me.psu.edu/rahn/me462/AD594_5_c.pdf chip. This multiplies thermocouple output by about 250 and applies cold junction compensation. The output can then be converted to temp by using the formulae and applying to K type nist tables. So will probably have another play at improving that (have had some thoughts about it), although this is unlikely to happen in the next few months.

I hope this answers your questions.

On a side note, I did run the wide band beside a narrow band during closed loop. That did record just over and under L1

Still not convinced about diagnostic values but tuning, :? who knows.

HTH
FF
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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby Steve Smith » Mon Sep 29, 2014 1:19 pm

Hello FF and thank you for the detailed reply.

I now need to print and digest all this information as I prefer to write thoughts onto your post and no doubt research the techniques used.

I will feedback as soon as I can and possibly raise further questions.

Thank you again for the input, take care......Steve
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Re: How to measure a Bosch LSU 4.9 wideband lambda sensor

Postby KimAndersen » Wed Oct 01, 2014 2:51 pm

Hello Fat Freddy

Your talk about the k-type thermocouple sensor made me think, why didn't I measure the exhaust gas temperature in my case study !!!

This engine is equipped with one EGT sensor right before the turbo and one EGT sensor before and after the diesel particle filter and these sensor are also the K-type sensor.

I must make a new capture of Bosch Wideband LSU 4.9 combined with EGT sensor before the turbo to see the how
temperature affect the the reading from the Wideband sensor - if this is the case or not !!!.

The simplest would be to hook up the VCDS and find the right measuring block, but there is nothing like a live signal from sensor itself.

Time will tell whether I can find the specification for that sensor.


Regards
Kim
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