Re: MFA swap woes

["T. Reed" <treed2@u.washington.edu>]

Hey all,

Finally the mfa swap is done. Last weekend I spent the whole weekend
getting the cluster parts swapped over and making the special adaptor to
enable the 8k tach gauge face to be used with the mfa circuit board in the
way. This weekend I actually went to the car to do the wiring. But
first, last night I took apart the switch. Well, actually I broke it
apart. There's no good way to open it up so I just kept prying in the
right spots, trying to make it break in some inconspicious location. After
that happened, I was able to extract its miniature inner workings. In
truth they really more exploded in my face. I picked up all the little
springs and metal balls and managed to figure out how it all went together
reasonably well. After that I popped the clips off the back of the stalk
that hold the wire for the MFA switch inside and I was able to get enough
slack in the wire for the MFA switch so that I could slide the circuit
board out and clean its metal contacts. And boy were they dirty... I could
see only a faint line that looked metallic - the rest was coated in some
black slimy crap that wasn't grease.. it was more like black and green
chalk. I spent some time cleaning up the contacts real good and then I
tried to get the switch back together. Now mind you, as I said before
these switches aren't meant to be taken apart. They also aren't meant to
be put together, apparently. You have to hold like six things together at
once while sliding the whole assembly back inside the switch housing. On
the fifteenth or sixteenth try I got it back together...

I used ordinary super glue to repair the broken piece of the switch
(luckily the part that broke doesn't experience any stress under normal
operation so I almost didn't even need to glue it). Installing the switch
on the steering column was straightforward. Besides connecting all the new
wires to the cluster wiring harness, I ran a ground wire for the mfa
switch down to the "ground distribution" rings by the fusebox and 3 wires
for the oil and air temperature sensors. Luckily, I found the stock
location that the MFA vacuum hose is routed through (its straight behind
the speedo, on the back wall) and popped the grommet out and was able to
run those 3 wires and the vacuum hose through it. Instead of running the
vacuum hose all the way through the rain tray to a T-fitting, I just
inserted a T-fitting inline with the vacuum line to the injection brain.
I didn't hook up the oil temp wire (I just left it zip-tied) because I
have the analog oil temp gauge, but everything else was hooked up so I
fired up the car. Nothing. Not even a clock - time to check the fuses.
Sure enough, in the course of my wiring job I had shorted something out
and blown fuse #3 (mfa and clock). Replaced it and the MFA came to life.

As far as I can tell everything works as advertised. Driving time works
'for sure', as does the clock. Miles driven seems correct, along with air
temperature. At first I thought the MPG was way off but when I did actual
calculations from gas receipts it was within +/- 1 mpg... Average speed
was initially all whacked, _way_ low, but after I reset the unit it worked
fine. I double-checked it by calculating average speed based on driving
time and miles driven (assuming those two are accurate) and it was right
on. Oil temp isn't hooked up, so it just reads '---' and air temp seems
like its working, but its pretty much been between 60 and 64 every time
that I've looked at it. I guess theres just not much temperature variation
next to the horn.. I have noticed temperatures rise when the engine is on
and lower when driving on the freeway, though.

Anyway, all this means that I think its working - which is a good thing,
considering what a pain in the ass it was to swap over. Let me re-iterate
over my previous advice: If you're going to do an MFA swap, get the
cluster from a car with an identical speedo/tach configuration. Don't try
and swap around components (except speedos, which are easy) because it'll
just turn out to be a total PITA.

Thanks to everybody who sent mail..

HTH,

-Toby


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