2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

afm position

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Old Jul 15, 2005 | 07:10 PM
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afm position

I have a TID mod on my 87 TII. However I was forced to run the whole thing slightly upwards from turbo. Is having AFM slightly tilted up (about 25*-30*) affect it's functionality ?

Btw here's a funny vid i found
just paste the link, should work

http://mark2.markscash.com/bookmark/...upinflames.wmv
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Old Jul 15, 2005 | 09:03 PM
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Yes, having it tilted will affect it's operation. IIRC, it will tend to read more airflow than actual (because of gravity pulling on the door), and you'll run rich.

-=Russ=-
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Old Jul 15, 2005 | 10:11 PM
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The TII model AFMS have a slightly stronger spring than the NA counterparts. I would agree with the above statement on an NA, but for a turbo engine AFM im not to sure if it matters if the incline is ever so slight.. any other opinions?
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Old Jul 15, 2005 | 11:06 PM
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Doesn't the AFM have some sort of counterbalance mechanism?
I just assumed there was a weight on the same pivot as the flapper door so that it wouldn't go flying shut when you jam on the brakes?

Ah, I just found a GREAT link on the AFM's.
http://www.atlanticz.ca/zclub/techtips/afm/

There is a "damper chamber" and "damper plate", but it does not seem to be perfectly balanced about its point of rotation, as I would have thought.

The upside is that you could do a simple test:
1) Unplug the AFM.
2) Measure the resistance from the wiper on the potentiometer to either side of the pot.
3) Set AFM as installed by factory.
4) Measure again
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Old Jul 16, 2005 | 10:02 AM
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any chance u would happen to know which tabs in the connectors to check for resistance?
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Old Jul 16, 2005 | 12:11 PM
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Read the FSM, it's in there. Should be in the engine fuel & ignition section, with the proper resistance ranges as well.

-=Russ=-
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Old Jul 16, 2005 | 12:19 PM
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yeah it's probably affecting my boost too. I noticed I've been boosting about 3 or more psi less.
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Old Jul 16, 2005 | 02:43 PM
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Originally Posted by fc3sguy
any chance u would happen to know which tabs in the connectors to check for resistance?
I'm not sure what your up to. But take this into consideration. The vane in the afm closes on a MECHANICAL stop. You can adjust the guts to your hearts content but each and every time the vane comes back to the SAME MECHANICAL stop.

There's only ONE exception. If you *loosen* the spring to such an extent that it now does not hit the mechanical stop, I can assure you that that afm will perform like a piece of junk. There won't be enough spring tension to keep the vane from hitting its full travel even under light loads.

The pins your looking for are the second and third ones from your right if the afm is in its normal upright position. I'll attach some jpgs of the afm internal and external parts later.

The above said, you SHOULD ohm out the afm to the fsm's figures. That WILL NOT guarantee the afm is good/reading as stock etc.
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Old Jul 16, 2005 | 02:47 PM
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From: FORT WORTH, TEXAS,USA
jpg
Attached Thumbnails afm position-afmguts.jpg   afm position-afmtop.jpg   afm position-afmbottom.jpg  
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Old Jul 17, 2005 | 09:59 PM
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Originally Posted by HAILERS
I'm not sure what your up to.
It was probably the link I posted that made things confusing.

As I understand it, he's just running the AFM at a slight incline, not messing with the spring. He just want's to know if a small tilt is going to significantly effect the sensor.
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Old Jul 17, 2005 | 10:12 PM
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The tilt won't make a difference. The tilt you described.
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Old Jul 17, 2005 | 11:12 PM
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Originally Posted by fc3sguy
yeah it's probably affecting my boost too. I noticed I've been boosting about 3 or more psi less.
Funny you should say that. I think I'm running into the same problem. And I thought I had my AFM pretty level.
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Old Jul 20, 2005 | 10:44 PM
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Originally Posted by HAILERS
The tilt won't make a difference. The tilt you described.

One person says yes one person says no. Still, I'm gonna try to level it out see If it makes a difference.
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Old Jul 20, 2005 | 11:05 PM
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I can't add anything to the AFM dicussion (Some of us are AFM Free! ), I would just like to say that having your car go up in flames in front of you would SUCK. I feel REALLY bad for the guy with the GTI.
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Old Jul 20, 2005 | 11:17 PM
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From: Ames, IA
The GTI video is yet another reminder to CARRY A BLOODY FIRE EXTINGUISHER in your car. It's a lot more likely to be useful than a random video camera... I'm pretty sure that fire could have been put out with a small fire extinguisher when it started.

-=Russ=-
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Old Jul 22, 2005 | 06:44 PM
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yeah
I like to jack threads, specially my own

which reminds me of this. Talk about knowing the road in your head.

http://videos.streetfire.net/Player....3-761051EFD4B3
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