Autonerdz forums

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...

Nice

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

Doc...

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

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



Martin

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

This looks like an analog MAF to me.

Mick

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.

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.

Martin

I nearly jumped in with the same interpretation.


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

cheers all

Dave