Today I disassembled my air flow meter because I wanted to make sure it was 100% functionning. The contact for the fuel pump signal is good. The air temp sensor is good. The total resistance of the potentiometer is ok but when I test the output of this one, there's a problem. That was the first thing I thought but I went to see a friend who has alot of used parts and all of them give the same reading as mine. So what are we supposed to read from this potentiometer output? What I've read about it on internet, said that this kind of air flow meter use a potentiometer, so I'm supposed to read a resistance from 0 ohm or so to a max value. What I read is like an erratic variation. My curiosity took the better of me and I then unsealed the cover and it looks like a potentiometer but with some kind of resistors tapped all along the potentiometer traveling path.



Does someone know how the ECU manages to find out where the flap is placed at any moment? That's a good one! he he. ???

 

Have you checked with the factory manuals?

 

In the factory manual, it's said that you should be reading 50-500 ohms when fully closed and 50-500 ohms when fully opened. In fact that doesn't help since no matter how far you push the flap in, you will always be reading between 50 and 500 ohms. I haven't found anything on internet yet to light me. I found a mod that can be done on miata using a RX7 air flow meter but doesn't give a hint that could really help to understand the principle. Miata air flow mod

I tried one of AFM I tested yesterday but nothing has changed. When the engine is not quite warm, it has almost no power above 4k and when warmed up I can feel some fluctuations in power but there's still loss of about 20 hp.

I've almost checked and changed most important parts with used one known as well functionning but nothing has changed. ???

 

I finally found a way to test it and being absolutely sure of it.

Thanks

 

which is what? someone else might also need it.

 

tell us or pay the consequences!!!!!!!!!!!!!!!!!!!!, hehe just kidding but hey let us all know how your doing it ,please it could help me out and everyone else on this site for all i know mine is going bad,i mean its a 14 year old car,only has 68,000 miles on it ut still its getting up there.please tell!!!!!!thanks for the answer













waste ricers,all of them!

 

which is what? someone else might also need it.[/quote]

It reminded me someone when I sent this short post! I did it on purpose. :smilewinkgrin:



How to test an air flow meter:

You need a 5-volt DC power supply and a voltmeter (a fast analog voltmeter is best for this but use a digital meter if you don't have analog).

- Connect the (-) of the voltmeter and the (-) of the power supply to E2.

- Connect the (+) of the power supply to Vref.

- Connect the (+) of the voltmeter to Vs.

Now you should be reading about 4 volts when the flap is completely closed.

Just open slowly the flap with your fingers and keep watching the voltmeter needle to see if it moves smoothly without any glitch. You should see a very smooth variation of voltage while you push the flap all the way inside to full opened position.

If everything is fine you should now be reading about 0.5 volt when fully opened. You should have a reading that is linear and follows exactly the motion of the flap. :sigh:



Note that the most important thing is to have no sudden fluctuation of the meter's needle while opening the flap, it needs to be smooth. If you get a glitch in some place, the air flow meter is faulty. :wow: