DIY AFM help

[Durty-Sanchez]

Right.. the AFM fixup guide! This is probably most relevant to early-mid 90's AFM's that have no servicible parts in them. The basic idea is that over time the solder joints on the connectors become dry and crack, which makes for a bad electrical connection and sometimes an error code. Even if no code is given, you may experience random loss of power from time to time, which can also be caused by this. Sorry about the blurry photos, it was a crap camera!

Anyway, moving on, you'll need:

Solder

Solder wick/sucker (optional)

Soldering Iron (preferably a hot one)

Knife

Silicon or some other kind of sealant.

 

1. Locate your AFM on the drivers side of the engine bay. It's attached to the airbox by bolts, and to the flexi-joint pipe by hose clamps. It's probably wise to unbolt the AFM completely from everything, although not necessary. You'll need to unplug it too!

 

 

 

2. After getting the AFM off you'll need to cut through the black sealant that lines the outside of the circuitry housing. The lid is quite deep so be careful when prying it out, I managed to crack the outer casing from prying too hard.

 

 

 

3. After you get the lid off you'll see a copper EM sheilding plate that is soldered down by one side. If the plate is loose then awesome, take it out, otherwise you'll need to remove the solder to get the sheilding plate out. Solderwick is great for this kinda stuff, but i'm sure there's more than one way to skin a cat.

 

 

 

4. Once that's out of the way you can see some of the circuitry involved in the mysterious AFM. Down one side you will see 4-5 connector pins that go from the main plug on the outer casing through to the circuit board (see number 3 on this incredibly blurry excuse for a photo). Usually these are the culprits! It's always best to remove the old solder before re-soldering, but you can probably get away with not doing that.

If you look down at the pins inside the casing you'll see that they are actually made up of 2 pins connected with a solder joint (one from the circuit board, the other from the plug). Heat the joint so the solder is liquid then remove the old solder, then add some more solder as necessary. If you don't have solder removing stuff then i'm sure that re-wetting the joint should be ok. Repeat for all of the pins.

 

 

 

5. You're done! Put the EM sheilding back on and re-solder it to the grounding connection. Then replace the plastic lid and seal it with sealant to keep moisture out. This should conclude your adventures in to the AFM, and should be enough to have repaired it. I've done several of these and never had any more problems with them afterwards. If you're problem persists then you may need to either buy a new AFM or find one on trademe.

Best of luck!

Edited July 24, 2017 by Joker
Duplicated images from PB to imgur

[Guest]

wow, is this not a stickie? it should be! it looks great!

-smurff

[Guest]

Hey thanx so much dude, ur awesome,

[ReubenH]

You links are broken, got some of this going on: http://"http://"

[Durty-Sanchez]

Fixed, was teh ghey interwebface. You weren't missing much, the pictures are so blurry they look better as thumbnails anyway

[Andrew NR]

Awesome thread! ;D

I've got a completely dead AFM that I'm going to muck around with first and if that's successful or it gives me a good idea of what needs to be done then I'm going to attempt to fix my partly faulty one.

I'll take some fresh (and in focus) pics when I pull the completely stuffed one apart.

[Andrew NR]

New "green label" AFM pics. Feel free to steal and photochop as you see fit.

[Andrew NR]

I've also heard that "electrical contact cleaner" works wonders on AFMs.

[nzkaosnz]

oh sweet. so this can be used on v3 etc afm?

[Guest]

Will using crc afm cleaner on a 2004 sti screw anything else up?

It can't hurt to try....or can it?

[B4_685]

Used contact cleaner on my B4 AFM with no issues

[Joker]

Saving these images before PB dies / also thread Bump!

 

The AFM DIY thread is the first and ONLY AFM topic in our Mega FAQ, got any better thread we should add? Let the mods know or post links in the FAQ thread

 

of if anyone feels like offering updates or better pictures PLEASE DO