afm test with analog meter

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jackstar
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afm test with analog meter

Post by jackstar » Mon Sep 06, 2010 6:41 pm

I am trying to test my afm with an analog multimeter just as tencents did on his vanagon. I hve tried to find some guidance in Bentley and on the various sites as to where I plug my leads into to check for dead spots but with no luck. I am sorry to have to ask a question that must seem pretty basic but I have to get this tested and I am running out of options. Thanks.

Jack

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LiveonJG
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Post by LiveonJG » Mon Sep 06, 2010 7:29 pm

I'm not sure about the thread you're talking about, but if you're just after a continuity test, you can set it up like this:

Image

Now move the wiper and make sure the needle on the meter doesn't move. Set your meter to either the highest Ohm setting or Cont.

Hope this helps.

-John
Keep it acoustic.

jackstar
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Post by jackstar » Mon Sep 06, 2010 7:36 pm

Thanks John, but there is a video that shows meter leads plugged into the wire harness of the AFM and you move the wiper while watching for the meter needle to fall away, in other words a dead spot. I may have to go find that video again and try each wire until I get what the video is showing. Thanks again for the post.

Jack

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LiveonJG
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Post by LiveonJG » Mon Sep 06, 2010 7:43 pm

Maybe so, but this will identify a dead spot as well. Watch the needle as you move the wiper.

-John
Keep it acoustic.

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Gypsie
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Post by Gypsie » Tue Sep 07, 2010 12:16 am

Bentley does have a write up about it in the fuel injection sec. 24 (in mine)

Sec. 24.9
posts 6& 7 and 7&8. Set the MM to show 1000ohms across the arc this will give you the biggest sweep during your afm wiper sweep. If you have digital that's fine too. no less than 40 and no more than 500
So it all started when I wanted to get better gas mileage....

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Randy in Maine
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Post by Randy in Maine » Tue Sep 07, 2010 4:14 am

79 VW Bus

jackstar
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Post by jackstar » Sat Sep 11, 2010 6:43 am

Ok. obviously I dont know what I am doing because I am getting nothing close to the results in the video. Can someone please tell which contacts (holes) to put which probe in so that I can test my 79 AFM? I tried (i think) every possible combination of probe locations and all I got was either no reading or pegging the needle. I would appreciate some input. Thanks.

Jack

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Randy in Maine
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Post by Randy in Maine » Sat Sep 11, 2010 9:44 am

79 VW Bus

jackstar
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Post by jackstar » Sat Sep 11, 2010 12:32 pm

Alright. My first born male child shall be named Randy Dwill. So let it be written. So let it be done. Thank you very much. Off to the garage.

Jack

jackstar
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Post by jackstar » Wed Sep 15, 2010 2:03 pm

Finally got a chance to check the afm per Dwill and his pics and the vane moved smoothly and so did the needle so there does not seem to be a problem there. Onto to something else. Thanks for all the guidance and assistance.

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LiveonJG
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Post by LiveonJG » Wed Sep 15, 2010 10:25 pm

What exactly is the trouble you are trying to isolate?

-John
Keep it acoustic.

jackstar
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Post by jackstar » Tue Sep 21, 2010 6:11 pm

Sorry to have been gone. I wasnt trying to isolate any real problem. I was simply checking out the AFM. It may sound geeky but I wanted to eliminate the AFM from some hesitation/slight bucking problems I had experienced. I suspect a vac leak somewhere. I just need to replace all the rubber to ensure it is tight and airproof.

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LiveonJG
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Post by LiveonJG » Tue Sep 21, 2010 11:02 pm

jackstar wrote:Sorry to have been gone. I wasnt trying to isolate any real problem. I was simply checking out the AFM. It may sound geeky but I wanted to eliminate the AFM from some hesitation/slight bucking problems I had experienced. I suspect a vac leak somewhere. I just need to replace all the rubber to ensure it is tight and airproof.
Not geeky at all. Hesitation and bucking is a fairly common trouble. I ended up replacing my engine wiring harness to clear it up. Are you running points? If so, swap out the condensor as a test.

-John
Keep it acoustic.

jackstar
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Post by jackstar » Thu Sep 23, 2010 6:56 pm

I am running Hall ignition. I realized that when I first got it and bought a set of points like it was my 79 SB. Talk about feeling stupid. As soon as I get a spare second to start, I will start replacing rubber. I have the throttle body gasket, the ones that are about 2 inches long, I will replace those first and work my way out. Hope to get finished before too long. I'll keep you advised. Thanks for the reply.

Jack

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Gypsie
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Post by Gypsie » Fri Sep 24, 2010 11:27 am

also look real close at your aux air boot. (the little 90 degree rubber piece that connects to a hose to the s-boot. nefariously infamous, that boot).
So it all started when I wanted to get better gas mileage....

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