Electrical What's inside a TFI module? (Gut pictures inside)

Trogdor

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Aug 30, 2018
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This is just for the curious like me that have wondered what's inside a TFI module and to see if there are any differences between manufactures. I have 6 TFI modules sitting on my workbench. Why do I have so many? I was chasing a distributor issue that turned out to be that my stock distributor had worn the shaft bushing that allowed the trigger wheel to contact the PIP. Anyhow, back to the different TFI modules I have:

  1. New Motorcraft replacement.
  2. Old Motorcraft, most likely original to the distributor.
  3. Generic Parts store replacement.
  4. A remote mount unit from a 7.5L F-350 (I'm going to try and make my own remote TFI one day).
  5. Module that came with a Cardone rebuilt distributor.
  6. Wells branded replacement.
As you can see they are all a little different inside. From looking at just how they are constructed, the Wells unit would probably be may favorite after and old Motorcraft unit. I like the way the connector pins are hooked up to the board, seems beefier than the other replacements. I would up breaking the cover on this one as it was really well bonded to the case. I don't know much of what is going on inside them so I can't really comment on board layout.

So now enough chit-chat and let's get to some pictures:

1. New Motorcraft replacement:
TFI 1 New Motorcraft.jpg


2. Old Motorcraft:
TFI 2 Old Motorcraft.jpg


3. Parts store replacement:
TFI 3 Parts store replacement.jpg


4. Remote TFI from F-350:
TFI 4 Remote unit.jpg


5. Module that came with the Cardone distributor:
TFI 5 Cardone.jpg


6. Wells branded replacement:
TFI 6 Wells.jpg
 
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7991LXnSHO

wanna catch the space herp
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I wonder how the epoxy affects heat dissipation? Aftermarket parts advertised it for vibration and water resistance.
 

Potomus Pete

Gretchen Whitmer is eating at me
Mar 7, 2019
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This is just for the curious like me that have wondered what's inside a TFI module and to see if there are any differences between manufactures. I have 6 TFI modules sitting on my workbench. Why do I have so many? I was chasing a distributor issue that turned out to be that my stock distributor had worn the shaft bushing that allowed the trigger wheel to contact the PIP. Anyhow, back to the different TFI modules I have:

  1. New Motorcraft replacement.
  2. Old Motorcraft, most likely original to the distributor.
  3. Generic Parts store replacement.
  4. A remote mount unit from a 7.5L F-350 (I'm going to try and make my own remote TFI one day).
  5. Module that came with a Cardone rebuilt distributor.
  6. Wells branded replacement.
As you can see they are all a little different inside. From looking at just how they are constructed, the Wells unit would probably be may favorite after and old Motorcraft unit. I like the way the connector pins are hooked up to the board, seems beefier than the other replacements. I would up breaking the cover on this one as it was really well bonded to the case. I don't know much of what is going on inside them so I can't really comment on board layout.

So now enough chit-chat and let's get to some pictures:

1. New Motorcraft replacement:
TFI 1 New Motorcraft.jpg


2. Old Motorcraft:
TFI 2 Old Motorcraft.jpg


3. Parts store replacement:
TFI 3 Parts store replacement.jpg


4. Remote TFI from F-350:
TFI 4 Remote unit.jpg


5. Module that came with the Cardone distributor:
TFI 5 Cardone.jpg


6. Wells branded replacement:
TFI 6 Wells.jpg
That's a lot going on inside there.....Very interesting thanks for the info. No wonder they cost a hundred bucks, and I wonder if they are handmade by small people with soldering guns
 
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2000xp8

SN Certified Technician
Aug 8, 2003
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That's a lot going on inside there.....Very interesting thanks for the info. No wonder they cost a hundred bucks, and I wonder if they are handmade by small people with soldering guns
Believe it or not, there really isn't much going on in there.
I've done quite a bit of minor board repair (have a pinball and arcade collection, if you don't fix them, you have to pay dearly and wait forever for someone else to) and that is probably about $5-$10 in parts (maybe even less).
Some things i've had to buy only come in packs of 100 for like $1. And that's pricing for "non bulk" purchases.

The reason they probably can't be repaired is that most guys handy with a soldering iron don't/can't do surface mount soldering (including me).

Kinda figures that they have gotten less reliable, the original's worked pretty well forever and then they changed the design...
 
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a91what

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SMD components can be done easily with a hot air gun and some solder wipe.. you can get a cheap-o solder station these days for under $100 on amazon.
You basically have 2 things happening in there... 1 is the circuitry that handles the pip, it is set so that it will fire the IGBT when the spout is removed at mechanical timing, very simple design it includes the trigger for the IGBT.
The IGBT is a high current device that can deal with the transient voltages associated with firing the coil [collapsing field ect] these are the expensive part [100 of them for a few bucks]
I actually designed a simple TFI replacement driver for the Mega-squirt crowd that even has CCD capabilities and its only 3 components lol.
 
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Bird76Mojo

Active Member
Jul 12, 2018
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While you've got one gutted, might as well make your own remote mount TFI harness and switch to the SN95 style distributor.. It's easy.

Mine has held up well for over 20,000 miles so far, and it runs at ambient temperature. When it was on the distributor, I checked it with an IR thermometer and it was well north of 200 degrees at all times once warmed up.

TFI relocation 1.jpg

TFI relocation 2.jpg

TFI relocation 3.jpg