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Thread: 95 240sx. Testing MAF. Am i doing this right?

  1. #1

    95 240sx. Testing MAF. Am i doing this right?

    I've been trying to test my MAF. I backprobed the Maf like the manual states but i've been wondering if I'm on the wrong setting.

    My multimeter is a pocket multimeter from power tools




    I'm supposed to backprobe the wire thats towards passenger side.. not the driver side right? Meaning if you were to look at the harness from your drivers seat.. it's the far right.. not the far left. (harness is between maf and driver) Correct?

    when i check the maf its on the DC V side like this on 10.
    [img=http://img120.imagevenue.com/loc111/th_40107_meter.jpg]

    I get a reading of .8 on the ac10v like this. (the red)
    [img=http://img9.imagevenue.com/loc40/th_40112_meter2.jpg]

    When i click it to the AC V on 10(i dont have a picture but i just click it 4 times counterclockwise.. look at the above pictures). I get a little past 2 on the ac10v scale.

    So my question is... Is it DC V (10) or AC V (10) that i should be using to test the MAF. And my second question... Am I reading it correctly on the needle? (the red scale where it says AC 10V right)


    and on this image
    the harness is disconnected. Are you backprobing or probing from the other side. I'm getting more confused.


    sorry for all the questions.

  2. #2

    Re: 95 240sx. Testing MAF. Am i doing this right?

    The MAF output voltage is DC, so your meter needs to be set to the DC scale.

    The output voltage wire on the MAF is the white wire. Test this wire while the car is on. At idle, you should be reading 1.3-1.7 volts and at about 4k rpm, it should be around 4 volts.

    Next check the MAF ground. This is the black wire on the connector. Turn your meter to test for ohms and put one lead on your tester to the black wire, the other to chassis ground. You should read close to 0 ohms.

    Lastly check the power supply. This is the black/white wire. With the key in the on position, probe this wire and you should get 12-14 volts. Make sure you're set back to DC on your meter for this.

    -Cosmo

  3. #3

    Re: 95 240sx. Testing MAF. Am i doing this right?

    that was extremely helpful. thank you.

  4. #4

    96 s14 throttle issues

    Quote Originally Posted by cosmoworks View Post
    The MAF output voltage is DC, so your meter needs to be set to the DC scale.

    The output voltage wire on the MAF is the white wire. Test this wire while the car is on. At idle, you should be reading 1.3-1.7 volts and at about 4k rpm, it should be around 4 volts.

    Next check the MAF ground. This is the black wire on the connector. Turn your meter to test for ohms and put one lead on your tester to the black wire, the other to chassis ground. You should read close to 0 ohms.

    Lastly check the power supply. This is the black/white wire. With the key in the on position, probe this wire and you should get 12-14 volts. Make sure you're set back to DC on your meter for this.

    -Cosmo


    This was helpful but I need some more help. My s14 will drive good unless you WOT they it cuts around 2.5....White wire was 1.4 idle but only 2.6 at 4k, i think this is because I got like 44ohms of resistance on the black wire smfh. power supply was good...my question is where should I look for now? where are the grounds for this circuit and could it be my low reference(ecu) ground???

  5. #5
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    Quote Originally Posted by faqz09 View Post
    This was helpful but I need some more help. My s14 will drive good unless you WOT they it cuts around 2.5....White wire was 1.4 idle but only 2.6 at 4k, i think this is because I got like 44ohms of resistance on the black wire smfh. power supply was good...my question is where should I look for now? where are the grounds for this circuit and could it be my low reference(ecu) ground???

    What do you mean it cuts? It feels like a fuel cut? Like a speed limiter?

    Describe the "cut". It is a sure cut, like a definite, exact, same RPM every time, exact same predictable place kind of cut??
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