Digital mass air flow sensor

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Digital mass air flow sensor

Postby lukevwaudi » Thu Oct 29, 2015 7:00 pm

Hello guys had the Pico a little while now but seemed to be struggling in converting the digital signal from mass air flow meters into a readable analogue signal. I convert to frequency on the drop down menu from channel letter and it still does not seem as I know it can be done. Any help be much appreciated cheers.
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Re: Digital mass air flow sensor

Postby Alan » Thu Oct 29, 2015 8:52 pm

Hi,

Are you following this guide?
https://www.picoauto.com/library/automo ... er-digital

Try posting the waveform here and we can figure out whats wrong.
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Re: Digital mass air flow sensor

Postby lukevwaudi » Sun Nov 01, 2015 11:29 pm

Hi thanks Alan I didn't know about that tutorial and I have only been using a single test lead not both piggy backed like shown. I will try this tomorrow thanks for the reply .
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Re: Digital mass air flow sensor

Postby lukevwaudi » Thu Dec 10, 2015 2:00 pm

Hey guys after trying the tutorial I am still not getting the correct signal I have been told that you need to either create a math channel or input some numbers once frequency option has been selected. However I am unsure of the numbers to enter. Cheers Luke.
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Re: Digital mass air flow sensor

Postby Steve Smith » Thu Dec 10, 2015 2:41 pm

Hello Luke and thank you for the post.

Could you post the captured waveform here so I can take a look at the raw signal?

Rather than using the frequency coupling feature, just measure the digital output (DC coupled)

Could you let me know the version of software you are using at present?

One more question (sorry) could you let me know the vehicle under test? (Manufacturer, Model, Year, Engine code etc)

Why I ask is that I have seen a number of vehicles with possible additional information contained within the digital MAF signal. (Peugeot)

The frequency coupling feature "crossing points" may need amending and I can experiment with these for you if you can help with the request above.

A maths channel or a "current" measurement may be alternative options

I hope this helps, take care.......Steve
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Re: Digital mass air flow sensor

Postby lukevwaudi » Thu Dec 10, 2015 7:51 pm

Thanks Steve I will take a recording and post it on here the vehicle in question was a 2012 vw transporter caac engine. However I am struggling on any vag vehicle with digital amm from 2.0tdicr engines to 2.0tfsi. I can manage to get a line plotted in frequency however never goes high enough when revved to make any sense at all barely moves. Clearly I am doing something completely wrong. Cheers again Luke
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Re: Digital mass air flow sensor

Postby Steve Smith » Fri Dec 11, 2015 12:32 pm

Hi Luke thanks for the feedback

I have looked on the waveform library for VW digital MAF around 2012 but have drawn a blank.

I will have a dig and delve here at Pico next week and see if i can reproduce the same symptoms.

If you get chance , a digital MAF signal DC coupled from idle to WOT captured on one screen with 1 MS would be great should the opportunity arise? (Here I can then look at the raw signal and check why this is presenting a problem)

We will crack this Luke for sure, take care.......Steve
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Re: Digital mass air flow sensor

Postby Steve Smith » Wed Jan 06, 2016 8:54 am

Hi Luke sorry for the late response.

I have been unable to find such a vehicle over the break but many thanks to Mark Stammers for the psdata file below

Mark has kindly sent over a Digital MAF capture from a 2.0L Audi A4 TFSI

A4 DIGITAL MAF.jpg


The "raw" signal is not present but the frequency coupled results are clear to see.

Audi_A4_2007_Petrol_DIGITAL MAF.psdata
(1.36 MiB) Downloaded 59 times


Could you load this waveform and utilise the settings upon your next capture?

Could you post your results (psdata file) good or bad so I can take a look?

Take care......Steve
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Re: Digital mass air flow sensor

Postby Steve Smith » Thu Jan 07, 2016 10:34 am

Hello again Luke, just received another waveform from Andy Crook on the same subject.

The frequency coupling thresholds need to be amended in order to view the Digital MAF signal.
Please see the image below.

Frequecny settings..jpg




Downloading the psdata file above will help

Take care......Steve
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