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peaceful warrior
Samba Member
Joined: January 22, 2005
Posts: 5271
Location: Taoswest, USA
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 Posted: Thu May 10, 2012 3:11 pm Post subject: |
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| Ahwahnee wrote: |
The cover can be stubborn if never removed before -- the sealant may also be inside the lip, an area where you cannot get at with your Xacto knife. If you can raise it just a tiny bit to get a very thing screwdriver or other wedge under the lid you can begin to work it loose. Once it starts to let go you're pretty much home free but you have to overcome that initial grip & stretch property of the sealant.
I use a lot less sealant on the reseal though you want it sealed enough to keep dust out. |
Thank you! 
_________________
"Two things are infinite: The universe and human stupidity; and I'm not sure about the universe." Albert Einstein
"Notchboy" says "Man up!"
"Tram" says " My bus is bigger than your bus."
66 13W Deluxe, 68 Westfalia, 87 Syncro.
TOOB Member #15
Brian |
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peaceful warrior
Samba Member
Joined: January 22, 2005
Posts: 5271
Location: Taoswest, USA
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| Posted: Sun May 13, 2012 4:05 pm Post subject: |
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| peaceful warrior wrote: |
| Ahwahnee wrote: |
The cover can be stubborn if never removed before -- the sealant may also be inside the lip, an area where you cannot get at with your Xacto knife. If you can raise it just a tiny bit to get a very thing screwdriver or other wedge under the lid you can begin to work it loose. Once it starts to let go you're pretty much home free but you have to overcome that initial grip & stretch property of the sealant.
I use a lot less sealant on the reseal though you want it sealed enough to keep dust out. |
Thank you! |
For anyone else doing this. I spent a couple of hours trying to get the plastic lid off. Well not all of that time as I was watching the Golf tournament. Anyhow, I found once I cleared most of the silicone out, it was much easier to pry up on the low side, above the wiring plug. If I had started there first, it would have take a minute.
_________________
"Two things are infinite: The universe and human stupidity; and I'm not sure about the universe." Albert Einstein
"Notchboy" says "Man up!"
"Tram" says " My bus is bigger than your bus."
66 13W Deluxe, 68 Westfalia, 87 Syncro.
TOOB Member #15
Brian |
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teej
Samba Member
Joined: November 26, 2010
Posts: 908
Location: Seattle
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| Posted: Sat May 26, 2012 6:11 pm Post subject: |
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Thanks to all you guys on this thread and tencentlife for making the great vid, I opened up the AFM today. There was a developing stumble off idle, occuring randomly, but noticeable when it occured. After I watched the video this seemed a plausible explanation.
Wanna guess where the voltage dropout is?
Interestingly, the dropout on my analog meter 10v scale seemed to be right around 2.2v, but it didn't drop all the way like in the vid, only down to 1.8v or so. Is the relationship to running that linear? I mean, that was exactly what the van was doing when it acted up, stuttering a bit but not all the way back to idle.
My fix was to move the board a fraction. According to the retest, it worked.
If anyone comes up with a good way to take out the three M3 x 8 screws holding the board down, please tell.
I tried using a soldering iron to heat the screw to soften the epoxy or whatever they used. I got one out, sheared the other with my little impact driver, and had to drill the head off the other. Amazingly the local Ace Hardware had that size, the one I took out was unfit for reuse.
This is where my fix becomes a potential hack: I used one new screw with blue loctite, and then a drop of epoxy in the other two holes.
Dip the tanatlum cap mod while in there.
Edit: My epoxy hack was bugging me so two days later I went back in, drilled out the remains, and tapped for M4 screws.
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1986+ Wolfsburg Weekender Pop-Top 2.3 WBX Manual Trans
Last edited by teej on Mon May 28, 2012 2:46 pm; edited 1 time in total |
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Ahwahnee
Samba Member
Joined: June 05, 2010
Posts: 10317
Location: Mt Lemmon, AZ
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| Posted: Sat May 26, 2012 6:39 pm Post subject: |
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| teej wrote: |
| ...If anyone comes up with a good way to take out the three M3x50 screws holding the board down, please tell. |
Indeed. I had a badly worn track and simply could not get those loose with any reasonable amount of force. I finally went the route of doing a double bend in the arm which worked fine but shifting the board would have been my first choice. |
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randiego
Samba Member
Joined: October 13, 2008
Posts: 75
Location: San Diego
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| Posted: Mon Jun 11, 2012 2:36 pm Post subject: |
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Thanks to tencent and everyone who contributed to this thread, I confidently popped the top off my AFM this past saturday.
My 2.1 has always run very well, the PO took good care of it (top end with AMC heads helped), nice comforting smooth low rumble at idle. Unfortunately it has sometimes had the stumbling acceleration issue and lately the power dropout (vanagon syndrome) has gotten worse, especially on steep hills.
I ordered the correct capacitor and it arrived friday. Installation was easy. The track for the wiper was worn and I wasn't able to loosen the screws holding the board, so I reluctantly did the bend in the wiper. I could feel the difference as it moved the along the track - better contact.
I've put 150 miles on the van since the repair and with fingers crossed I'm declaring my problems solved! Much smoother acceleration curve and no drop outs. I was accelerating up steep hills! I'd swear my gas mileage is better... but it will take another fillup or two to confirm.
Without finding this thread I wouldn't have had the confidence to pop that cover off... 
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'85 GL, 1.9, 4spd (Sold, we'll miss it)
'89 Carat, Bordeaux Red, 4spd 2.1 |
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Ahwahnee
Samba Member
Joined: June 05, 2010
Posts: 10317
Location: Mt Lemmon, AZ
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| Posted: Mon Jun 11, 2012 4:55 pm Post subject: |
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FWIW -- In addition to the cap and positioning for a fresh track I added an auxiliary wire to strengthen the connection at the pivot. No idea if this will ever help (saw it on a Portia website) but I thihk later AFMs used a similar arrangement.
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Vanagon Nut
Samba Member
Joined: February 08, 2008
Posts: 10524
Location: Sunshine Coast B.C.
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| Posted: Fri Jul 06, 2012 3:32 pm Post subject: |
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Thanks again Tencent.
That test is great.
@ others.
FWIW, I found the range of my AFM was 0.25 - ~ 4.5 volts. As Tencent notes, if you move the flap slowly, you can use a DVOM. I saw increments of ~ 0.15 or 0.20 volts on mine.
This is with the wiper (board actually) moved to new portion of resistive strip.
And, for any newbs, I found the gasket between AFM body and plastic to be rubber. Was thinking I'd have to break out a ball peen and make a new paper gasket. 
Neil.
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1981 Westy DIY 15º ABA
(VW Gas I4)
1988 Westy DIY 50º ABA
VE7TBN |
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wrocek
Samba Member
Joined: June 08, 2013
Posts: 397
Location: North Illinois
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| Posted: Fri Jul 18, 2014 7:59 am Post subject: Re: AFM signal testing with video |
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According to photobucket this video was deleted or the name has been changed.
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159 2001 678, FI convertible.
AJ 133584*
Made Monday, September 18th, 1978 -> 381-9460 |
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tencentlife
Samba Member
Joined: May 02, 2006
Posts: 10163
Location: Abiquiu, NM, USA
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| Posted: Fri Jul 18, 2014 12:24 pm Post subject: |
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I can't make any of my videos on photobucket play, yet same files downloaded from there play on my computer. Try downloading the file and if that works for you, great; if not, oh well. The verbal description here should tell you enough to do the test without the vid.
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Shop for unique and useful Vanagon accessories at the Vanistan shop:
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also available at VanCafe.com!
Please don't PM here, I will not reply. |
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atomatom
Samba Member
Joined: May 15, 2012
Posts: 1911
Location: in an 84 Westy or Bowen Island, BC
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| Posted: Fri Jul 18, 2014 8:38 pm Post subject: |
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the download worked for me - (on the right, under "Media Options").
i stuck it on youtube. if that isn't cool, i'll remove it.
Link
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84 Vanagon Westy, 1.9L, California raised but defected to Canada. |
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tencentlife
Samba Member
Joined: May 02, 2006
Posts: 10163
Location: Abiquiu, NM, USA
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| Posted: Sun Jul 20, 2014 2:33 pm Post subject: |
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I would like to have been asked first, but I'm basically cool with you leaving it on Youtube as long as you observe Fair Use rules by saying prominently that it is my video, right up top under your name.
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Please don't PM here, I will not reply. |
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atomatom
Samba Member
Joined: May 15, 2012
Posts: 1911
Location: in an 84 Westy or Bowen Island, BC
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| Posted: Sun Jul 20, 2014 9:20 pm Post subject: |
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sorry about that - i did think twice about doing it - i erred on cautious by not making it a 'public listed' video (ie, only a direct link can find it).
i will update and give credit to you - unless you want to put it up and i'll just remove my copy. my intent was only to make the video accessible - not seeking fame, fortune or law suits.
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84 Vanagon Westy, 1.9L, California raised but defected to Canada. |
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tencentlife
Samba Member
Joined: May 02, 2006
Posts: 10163
Location: Abiquiu, NM, USA
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| Posted: Mon Jul 21, 2014 6:39 am Post subject: |
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No it's fine there, thanks for keeping it alive, and I see you already fixed it, so that's great.
You might as well make it public too, since it's educational and applies to a slew of other L-jet cars.
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Please don't PM here, I will not reply. |
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heiko910
Samba Member
Joined: November 15, 2013
Posts: 222
Location: Gardnerville, NV
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| Posted: Mon Sep 08, 2014 4:53 pm Post subject: Re: AFM signal testing with video |
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| tencentlife wrote: |
Here's an iddy biddy viddy I took while testing an AFM that was giving some trouble. Symptoms were hesitation off-idle, and intermittent missing while under load in low-mid-range rpms (under 3200rpm).
The Bentley test confirms circuit integrity, but doesn't tell you what you really want to know, which is that the ECU is receiving a variable signal between 0V and 5V that is smooth, uninterrupted, and linear with relation to the air vane position. This test shows the actual signal as the ECU would see it. By the way, this customer had already done the Bentley tests himself with an ohmmeter and found nothing that was outside specs.
You want to use an analog meter; a digital one has a periodic refresh rate so it doesn't do a good job of showing a steadily changing reading, when constancy and steadiness is what you need to confirm. Basically, it's an analog signal, so it is best represented with an analog instrument. You could do the test with a digital meter, but you would want to move the vane very very slowly so you could see the parts where voltage drops out, if it does.
I removed the AFM from the filter box to have access to the inlet so I could deflect the air vane itself. This also obviates the need to remove the cover simply to test the part (although you will need to remove it to repair the meter if it does test as bad). On this particular AFM, moving the wiper hub at top did not show any problems, while moving the air vane did, so even slight pressure on the wiper hub can alter the pressure of the wiper on the track enough to mask a problem.
After unbolting the AFM from the filter box, I plugged it back into the vehicle wiring, and switched on the ignition so the ECU would be feeding it's regulated 5V output into the potentiometer. That voltage is reduced variably by the resistance of the wiper board, and what comes out is the 0-5V signal the ECU needs to calculate air mass. If you have a regulated 5V supply, you could bench test the AFM by inputting the 5V at pin 3.
The voltage signal is on pin 2 (pins are 1-4 left to right when viewed from the rear as installed; they are also numbered on the male connector flange of the AFM), and 4 is grounded inside the ECU, so you want to test V between 2 and 4. Use a low range on the meter; I have this meter on a 2.5V range. Even though the actual reading across the entire scale will be from just above zero to about 4.5V, I'm most interested in seeing the lower half of the range because that's where the wiper spends most of its time, so that's where wear will occur. At idle the signal will normally be around 1V, so at every opening of the throttle it has to sweep thru the area just above one volt. Consequently that is where the most wear will be found, and that is the range that will cause the hesitation on tip-in and load hesitation that this customer complained of.
Clicking on the pic will take you to the Photobucket site. Have the sound up because I'm explaining what I'm doing and what you're seeing.
Here's the URL if clicking on the image doesn't play it for you:
http://s105.photobucket.com/albums/m218/tencentlif...V02923.flv
An AFM that shows dropouts can usually be repaired. First remove the cover, and then I first try spraying the wiper track with electrical contact cleaner while moving the wiper across it a bit to also clean the wiper tips. Then test again.
If cleaning doesn't restore smooth signal, there are two ways to reposition the wiper to run on a different radius of the track. First choice and simplest is to loosen the screws that hold the wiper board down and slide the board toward or away from the wiper hub. In this AFM I couldn't get the screws to break free, so I used the second choice solution. I used a bent scribe and a small screwdriver to make a slight double bend in both sides of the copper wiper arm itself, just enough to move the wiper tips a tiny bit closer to the hub, so it will run on a fresh line on the track. This restored smooth signal output in a subsequent test, and the van now runs smooth and the customer is very happy.
The other test to be done is the Intake Air Temp sensor, which is just an exposed NTC thermistor wired between pins 1 and 4. An ohmmeter and knowing the ambient temperature are all that's needed to check that, according to the temp/resistance table in Bentley. The IAT is very rarely bad, whereas the AFMs physically wear so after 20 years of use it's not at all uncommon to find them in this kind of condition.
The test will be exactly the same with both 2.1 and 1.9 WBX AFM's. It could also be done on earlier L-jet injections, but the pin positions will vary. I think that the signal output on L-jets would be #7, but you would need to verify. |
please help. the video is not available anymore |
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denwood
Samba Member
Joined: July 29, 2012
Posts: 1047
Location: Thunder Bay, Ontario, Canada
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| Posted: Mon Sep 08, 2014 5:34 pm Post subject: |
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Look up three posts. Same vid, just on youtube
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The Grape |
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heiko910
Samba Member
Joined: November 15, 2013
Posts: 222
Location: Gardnerville, NV
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| Posted: Tue Sep 09, 2014 5:32 pm Post subject: |
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| denwood wrote: |
| Look up three posts. Same vid, just on youtube |
Thank you, got it. |
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porterbrown
Samba Member
Joined: February 25, 2005
Posts: 718
Location: Bentonville, AR
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| Posted: Sun Sep 14, 2014 9:22 am Post subject: |
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Thanks!
Tested mine and it passed. Was also a good time to clean-up the filter box inside and out, which was a bit of a mess.
I did notice that the air vane flap and air canal were coated with a very thin coat of grease and dirt. Also noticed that the tube leaving the AFM had a coating of oil and/or gas....either way, it was slightly wet inside. Is this normal?
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'90 Westfalia GL Automatic |
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ohhorob
Samba Member
Joined: September 26, 2013
Posts: 217
Location: Santa Cruz
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| Posted: Wed Dec 17, 2014 1:53 am Post subject: |
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Here's a quick clip of what a worn-out track on an AFM looks like on a bench-test with an analog multimeter..
Link
I'm using a piece of firm plastic tubing to move the AFM flap (as opposed to moving the wiper directly) I also set my meter to 2.5 volts range, making the needle more sensitive to voltage change (the meters next range up is 10v, and the wonky signal is not as obvious)
I recorded the multimeter and wiper arm together, but edited to zoom and move each to make it easier to see.
When you do the test, move the arm very slowly.. there is a time constant affecting the response of the multimeter needle. If you move too quick, the response time of the meter will keep the needle smooth, and you won't notice the wonky signal from the little bit scratched-up wiper track. The ECU will notice.. I don't have measurements, but it definitely samples the AFM faster than my analog multimeter in DC volts mode!
I ended up spraying with electrical cleaner, and adjusting north just a touch. The signal is a lot cleaner, and a test drive confirms a stable RPM at engine loads that the AFM picks up signal from that area.
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"Gundy" - '85 Westfalia
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tencentlife
Samba Member
Joined: May 02, 2006
Posts: 10163
Location: Abiquiu, NM, USA
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| Posted: Fri Dec 19, 2014 8:12 am Post subject: |
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| Quote: |
| When you do the test, move the arm very slowly.. there is a time constant affecting the response of the multimeter needle. If you move too quick, the response time of the meter will keep the needle smooth, and you won't notice the wonky signal from the little bit scratched-up wiper track. The ECU will notice.. I don't have measurements, but it definitely samples the AFM faster than my analog multimeter in DC volts |
No, there's no sampling rate with an analog meter like there is with digital, it reads constantly, that's what makes it analog. What you saw was the dropout being too short to overcome the mechanical damping in the meter movement. That actually says it's a pretty well-made movement. In any case, to catch very small dropouts that the ECU will indeed see, the slower the better when you move the AFM vane.
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Shop for unique and useful Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
also available at VanCafe.com!
Please don't PM here, I will not reply. |
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smd333
Samba Member
Joined: September 08, 2018
Posts: 57
Location: Maryland
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| Posted: Fri Feb 01, 2019 8:53 am Post subject: Re: AFM signal testing with video |
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| tencentlife wow such a helpful video. ANd thanks to atomatom for putting it on youtube, I couldn't watch it on photobucket at all (that site has fallen into the abyss) |
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