General Bench Testing EVO 8 MAF

[DG-FNR]

I have a project in which I am going to characterize the flow measurement curves of the 3000GT and EVO 8 MAFs by flowing air through a metered orifice, calculating the CFM through that orifice using a manometer, and recording the frequency that the MAF reports at that CFM.

My end state is determining at exactly what flow value each sensor clips out.

To that end, I have built a rig with the ability to interpose orifices of various diameter and read the pressures on either side of that orifice. The rig also has a mount flange for an EVO 8 MAF (which I know is really a Karmann Vortex volume sensor, not a "real" MAF)

Today I made the wiring harness for the MAF connector.

Looking into the sensor, I have (left to right)

Pin 1 - +5V
Pin 2 - Baro Pressure
Pin 3 - MAF signal
Pin 4 - +12V
Pin 5 - Ground
Pin 6 - Air Temp
Pin 7 - NULL

Pins 1 and 5 are connected to a DC power supply set to +5V.
Pins 3 and 5 are connected to an oscilloscope (the ground wire from Pin 5 is connected to both the power supply ground and the scope)

When I connect the power and blow air through the meter, I get no measurable signal on the scope. Changing the air volume make no difference.

When I connect the scope to a frequency generator, I get the test wave - so the scope works.

Does the MAF need +12V? Both +12 and +5?

Anyone ever bench test one of these things?

 

[Drewpy Dawg]

Yes, the MAF needs both 12volt and 5volt.

Pin 1 - 5 volt power
Pin 2 - Barometric sensor
Pin 3 - Airflow
Pin 4 - 12 volt power
Pin 5 - Sensor ground
Pin 6 - Intake Air Temperature
Pin 7 - Reset

 

[steve]

Pin 3 is pulled up to +5v by the ECU and the MAF pulls it down to create the waveform. Without it you won't see anything.
Pin 6 is also pulled up and the ECU then measures how much the voltage is pulled down by the IAT sensor

 

[DG-FNR]

Pin 3 is pulled up to +5v by the ECU and the MAF pulls it down to create the waveform. Without it you won't see anything.
Pin 6 is also pulled up and the ECU then measures how much the voltage is pulled down by the IAT sensor

So this?

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[steve]

That should work.

 

[We're on Boost]

@DG-FNR Just a request, after you've used that Rigol DS1202Z-E oscilloscope for a while, maybe you could let us know what you think of it.

 

[DG-FNR]

Aha!

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[steve]

Looking forward to seeing where it all goes. Good Luck. Glad I could help a little.

 

[We're on Boost]

Aha!

That's a heck of a cool setup! Nice job shooting the video except for one thing - was hard to read or even guess at the numbers at the bottom of the scope, where it shows "Freq" and "Period".
I think if you hold the phone "sideways" to get the horizontal layout (landscape) instead of vertical (portrait), it will upload to YouTube as a regular landscape video rather than a Short. Not sure, I haven't done this enough to be for sure about how YouTube does it. It might also have to be longer than some certain number of seconds? I don't know.
Anyway as it is, it wastes most of the screen area on a computer monitor. So even on a 30 inch monitor, I can't really read some of the stuff shown on the scope. Just a suggestion!

 

[DG-FNR]

That's a heck of a cool setup! Nice job shooting the video except for one thing - was hard to read or even guess at the numbers at the bottom of the scope, where it shows "Freq" and "Period".
I think if you hold the phone "sideways" to get the horizontal layout (landscape) instead of vertical (portrait), it will upload to YouTube as a regular landscape video rather than a Short. Not sure, I haven't done this enough to be for sure about how YouTube does it. It might also have to be longer than some certain number of seconds? I don't know.
Anyway as it is, it wastes most of the screen area on a computer monitor. So even on a 30 inch monitor, I can't really read some of the stuff shown on the scope. Just a suggestion!

The whole purpose is for it to be a Short.

You aren't intended to read the scope - just to see that the waveform works and changes with airflow.

 

[Drewpy Dawg]

Would be interesting if you can test a Montero/Eclipse 482 MAF as well. They're supposedly very close to the EVO 399 MAF, but much cheaper and easier to find. I'd love to see actual data on just how close they really are.

 

[DG-FNR]

Would be interesting if you can test a Montero/Eclipse 482 MAF as well. They're supposedly very close to the EVO 399 MAF, but much cheaper and easier to find. I'd love to see actual data on just how close they really are.

Once I have the test protocol worked out - and verified that the leafblower moves enough air (or found an alternate blower setup that does) I intend on testing every MAF I can get my hands on.

We should have done this ages ago.