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I just pulled my error codes and i got code 31. I have an OBD-I computer, so it refers to the Mass Air Flow Meter Circuit. I think that the MAF is the plug that goes into the air intake right after the filter, right? I unplugged it and plugged it back in, but it still doesn't work. How should i go about fixing this. Here's a link to the other thread about this problem... http://www.supraforums.com/showthread.php?s=&threadid=30218 . Any and all help will be appreciated.


Here is the problem with my car:
I just got back from college and i took the supra out for a spin. When i had left it, everything functioned fine, no malfunction lights on, etc. However, when i drove it today, the first thing i noticed was that it didn't crank on the first try, but it always cranked on the second try. The second thing i noticed was that the throttle on my S-AFC read 0% constantly, regardless of my throttle position, and it previously used to work just fine. On top of this, i get the check engine light, trac off light, and MIL come on. So i take it out for a quick drive to see what's up, and the first time i get on it... the second turbo doesn't come online. Now, it worked PERFECTLY fine before i left to college. The only thing i did was take the battery out of the car before i left to college and put it back in today. Can anyone please help me? This is beginning to turn into a nightmare.
 
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someones been rippin on you shit while youve been at college.... check for extra batteries around..hehe... no you may have a vsv thats not working they get stuck sometimes when not used... or maybe a cracked vaccum from the vsv.... as for the safc cant help ya.... Kevin..
 
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If this helps any, the car runs the same whether or not the MAF is plugged in. What should that tell me?
 

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Have you tested the MAF to see if the output voltage fluctuates when air is blown through it? I don't have a scanner so I can't post the actual diagram of the connector to tell you which wires you have to tap into. So I drew up a real cruddy paint of the MAF and pins. With the connector facing you and the air inlet on your left, the E21 pin is the leftmost. The VG pin is the 4th pin from the left.

For testing:
Keep the MAF plugged into the wiring harness of the car.

Using a voltmeter, connect the positive tester probe to the pin VG, and the negative tester probe to E21.

Blow air into the MAF meter, and check that the voltage fluctuates. If the voltage doesn't fluctuate the MAF is bad.

If its bad please sell it to me.

John B.
 
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Discussion Starter #6
He's definately got the right idea there, if it's broken- just buy a VPC :)
 
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mistersolo said:
Have you tested the MAF to see if the output voltage fluctuates when air is blown through it? I don't have a scanner so I can't post the actual diagram of the connector to tell you which wires you have to tap into. So I drew up a real cruddy paint of the MAF and pins. With the connector facing you and the air inlet on your left, the E21 pin is the leftmost. The VG pin is the 4th pin from the left.

For testing:
Keep the MAF plugged into the wiring harness of the car.

Using a voltmeter, connect the positive tester probe to the pin VG, and the negative tester probe to E21.

Blow air into the MAF meter, and check that the voltage fluctuates. If the voltage doesn't fluctuate the MAF is bad.

If its bad please sell it to me.

John B.
John, i'm a little confused by ur explanation. You said to test it to keep the MAF plugged into the wiring harness of the car, but if i do that, how can i put the voltmeter on this pins? Well, what i did is i took the MAF unit completely out of the car, my dad held the voltmeter on the pins while i blew into it and the voltmeter read 0 v across it steady. We then put it in front of a fan and it still read 0 v. However, if it has to be plugged into the wiring harness of the car, do i tap into the wire for those pin locations. Also, should the car be running or should the ignition switch be on with the engine off, or should it just be off? Thanks for your help, i was just a little confused by how to test the unit.
 

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The wire connector must be plugged in. The MAF will get it's reference voltage thru the wiring connector, so the ignition switch must be on, but the car shouldn't be running. You will have to connect the volt meter thru the back of the wire connector or actually tap into the wiring. It's preferred that you don't pierce the wires, but you may have to. Sometimes you can put paper clips into the back of the wiring connector where each wire enters and hook the volt meter to the paper clips. Be very careful to not cross the paperclips.

Let me know if this works for you.

John B.
 
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Well, i tested it as u said and the voltage varied from .6 to 4.1 when i blew into it, so i guess my MAF is good. I have NO idea what idea is wrong with my car. Any suggestions would be greatly appreciated.
 
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Discussion Starter #11
KansaiSupra said:
disconnect your s-afc....that should do it..
I've checked all the connections for the S-AFC and they're all fine... how is disconecting the S-AFC gonna help?
 

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Since the S AFC runs a circle through the MAF the wire or SAFC might have shorted out causing the MAF check engine code to go off. What I mean is, since the SAFC is a loop and not just (tapped in ie O2 sensor or Speed senor) it could cause a short.


leonard
 
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