We have been discussing this in the Picogroup area and I thought it was time to bring it into the Public area.  I'll just start with the image.

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Hi Tom,

Are you using a pico current clamp to capture that?

There is some discussion over here using low amps for diagnosing broadband sensors and digital MAF but with considerably more expensive clamps than the pico one.

Cheers

Doc...

Hi Doc,

No this is not the Pico one.  This is the one Frank Massey was using.  They are expensive but we think there will be more and more uses for them.  

Makes no sense to me to use them on a digital MAF though.  The PCM is looking at frequency and therefore so should we.   ;)  The probe cannot respond fast enough to show you a frequency drop out anyway.

We will be offering these probes very soon.

Nice :)

They are on my wishlist (2x) along with 2 pressure transducers.

Doc...

It was previously impossible to see AFR sensor activity with a scope.  You could cobble in a GMM in series in an attempt to graph current but that's very intrusive/difficult and the results were not very good. These probes allow you to monitor the activity with the scope easily without opening up the circuit.   :)

We will have the K110 micro amp probes here Friday.  We have put up a page now where you can get more information and purchase.

Initial quantities are limited.

http://www.autonerdz.com/microprobe.html

Hello Tom, you posted “Makes no sense to me to use them on a digital MAF though.  The PCM is looking at frequency and therefore so should we.   The probe cannot respond fast enough to show you a frequency drop out anyway”. Frank has carried out intensive research and development with the new clamps and the PCM is looking at frequency. But Frank has compared the capture of analogue MAF sensor voltage and the new clamp. And noted the digital MAF sensor current reacts the same.
This gives an MAF capture that we can all recognize and compare it with the Lambda sensors for looking at fuel trims etc.
http://img80.imageshack.us/img80/88/autonerds.png

Uploaded with ImageShack.us
You can see the new clamp in action on here, Page 7
http://content.yudu.com/A1n8zq/AI6/resources/index.htm?referrerUrl=`
Best Regards, Martin.
________________________________________________________________________
www.wainwright-bros.co.uk          

martinw wrote on May 31^st, 2010 at 1:37pm:

Hello Tom, you posted “Makes no sense to me to use them on a digital MAF though.  The PCM is looking at frequency and therefore so should we.   The probe cannot respond fast enough to show you a frequency drop out anyway”. Frank has carried out intensive research and development with the new clamps and the PCM is looking at frequency. But Frank has compared the capture of analogue MAF sensor voltage and the new clamp. And noted the digital MAF sensor current reacts the same. This gives an MAF capture that we can all recognize and compare it with the Lambda sensors for looking at fuel trims etc. http://img80.imageshack.us/img80/88/autonerds.png Uploaded with ImageShack.us You can see the new clamp in action on here, Page 7 http://content.yudu.com/A1n8zq/AI6/resources/index.htm?referrerUrl=` Best Regards, Martin. ________________________________________________________________________ www.wainwright-bros.co.uk

Martin

Can you show us a digital MAF wave with the amp probe?

This looks like an analog MAF to me.

Mick

Martin

Can you show us a digital MAF wave with the amp probe?

This looks like an analog MAF to me.

Mick

Hello Mick, you’ve hit the nail on the head, it dose look like an analog MAF.
Toms capture red channel is an digital MAF at the top of this posting.
Martin.
______________________________________________________________________
www.wainwright-bros.co.uk          

Thanks for the image, Martin.   :)

Better to attach images here though so they are uploaded to our server.  We have had many great images vanish from these forums because the service that hosted them went away or the images were moved.  Attaching them here preserves them and ensures that they will not vanish   ;)

I would like to see the data file to examine it but I stand by what I said.  There may be a airflow/current relationship on some MAFs but nevertheless, that's not what the PCM is using.  As a matter of sound scope technique, it's always best to not try to infer one thing from another unless there is no other method.

MAF signal can be sampled directly with the scope so there is no reason not to do that..  It appears that is what you have done there on channel A for the analog variety.

Frequency MAFs can also be sampled directly with the scope.  Or...Now with the new higher range frequency graphing available on the 4000 series scopes, simply graph the frequency, if desired.

If you are sampling a frequency MAF signal directly, you will capture any signal drop out with the scope set up properly.  Even if you can establish a direct frequency to current relationship, the micro current probe does not have a fast enough response time to be reliable at catching a momentary glitch in signal frequency output.

Lots of additional unanswered questions there too..how fast does the current actually respond to a signal glitch?  Would it respond the same way for a signal fail high as a fail low?  For different MAF designs?  ETC....See where I am going with this?  It's all very interesting, but reliable scope technique?

The micro current probe had many great potential uses.  Experimentation is a great way to discover them.  I just fail to see the practical application of this method or any advantage over direct signal sampling.

Martin,


Quote:

Toms capture red channel is an digital MAF at the top of this posting.

Could be we have a terminology difference across the pond but that is what I would call a hot wire analog MAF.  The signal is a variable voltage not a variable frequency digital signal.

Reading between the lines here.... Martin has mistook the MAF signal as the subject in question. When in reality we are discussing the AFR sensor.

Martin

that MAF signal is a "convensional" analogue type.

Bang on Dave, :-[

Martin

I nearly jumped in with the same interpretation.
[smiley=banghead.gif]

let's put it down to the "pond" hey! ;)

cheers all

Dave  

Hi Tom, I’d better keep an eye on my terminology here.
Continuing this on testing Digital Mass Air Flow Sensor’s it looks’s like Pico was one
step ahead.

http://www.picoauto.com/tutorials/testing-digital-maf-sensors.html

I have to take my hat off to Frank for sourcing the Micro Prode to help with frequency witch has prompted Pico to develop a vertical scale in frequency as you posted. Can you graph the frequency on 4 channels at the same time Tom with the 4000 range?
Best Regards, Martin.
_______________________________________________________________________
www.wainwright-bros.co.uk          

martinw wrote on Jun 13^th, 2010 at 9:27am:

Can you graph the frequency on 4 channels at the same time Tom with the 4000 range?

Martin

No, frequency only works on one channel at a time.  However, it can be any one of the 4 channels that you want.

Hi Martin,


Quote:

I have to take my hat off to Frank for sourcing the Micro Probe

Indeed.    [smiley=notworthy.gif]    Great little tool.

Just to add to what John said.

Pico has got the frequency graphing capability a few builds ago (4000 series auto scopes).  However, the most recent 6.4.28.0 build extended the frequency range to the point that we can look at MAFs with it.  It's still a work in progress and is a bit to sensitive to noise on the signal at this point but improvements are already in the works.   ;)

Mick wrote on May 31^st, 2010 at 1:50pm:

Can you show us a digital MAF wave with the amp probe? This looks like an analog MAF to me.

hello, I know this is from an old post but i just got my K110 and wanted to try it out on my truck.

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Hey Tom, I looked for the mA probe in the Autonerdz main page, and they aren't listed.  Out of stock?  How much were they?

N8 wrote on Feb 12^th, 2014 at 7:46am:

Out of stock?

We discontinued that item.  Amazon started offering them and we could not compete and make any money on them.

They are stupidly expensive.  Over $600.

Still the only probe that is capable of doing these things though, as far as we know.

Thats what I heard on scannerdanner too...  Damn expensive.  Well I guess using the propane method while monitoring fuel trims will be my goto method of testing them until I muster up the money for that beast.  I want to get a couple other tools first though.