Burning through multiple TFI modules

[DarrenA]

Hello, everyone. I'm new to this forum and recently bought a 1985 Ranger 2.8 4x4. After a day of driving it, it suddenly quit on me while accelerating up a hill near my house. Engine cranks, gets fuel, but no spark. Me and my brother went through the ignition system and after some research, we concluded that the TFI module on the back of the distributor was the issue. I ordered a replacement from rock auto and the truck started right up again. I proceed to drive the truck for a couple of days and then it happens again. Same as before. Apparently, this is just normal with these trucks to roast these modules but this quickly, really? My question is what do most people do to avoid this issue and are there any specific TFI module replacements I should buy for best results? Any feedback is appreciated.

 

[Uncle Gump]

Be sure to use the proper grease to help dissipate heat on the backside of the module.

You can also remote mount the TFI over on the fender. Article in the Tech Library to do this. Also Mcully racing engines sells a kit to do this.

Most aftermarket parts are a crap shoot fir quality. Motorcraft is typically the best. Even used one from the scrap yard is better then most aftermarket units.

 

[AndyB.]

The Motorcraft ones have gotten expensive Motorcraft part number DY-425, Ford part number E43Z-12A397-A. Be sure to use heat sink compound on the back and tighten it securely to the distributor—the distributor is the heat sink to keep it cool.

I’ve owned my ‘85 2.8 since 1996, and I’ve gone through one module (it was misdiagnosed and was likely fine).

if you can’t find a NOS Ford module, let me know and I’ll sell you one of mine.

 

[DarrenA]

Be sure to use the proper grease to help dissipate heat on the backside of the module.

You can also remote mount the TFI over on the fender. Article in the Tech Library to do this. Also Mcully racing engines sells a kit to do this.

Most aftermarket parts are a crap shoot fir quality. Motorcraft is typically the best. Even used one from the scrap yard is better then most aftermarket units.

Those Mcully kits look simple enough to install, I think I'll go with one of those

 

[DarrenA]

The Motorcraft ones have gotten expensive Motorcraft part number DY-425, Ford part number E43Z-12A397-A. Be sure to use heat sink compound on the back and tighten it securely to the distributor—the distributor is the heat sink to keep it cool.

I’ve owned my ‘85 2.8 since 1996, and I’ve gone through one module (it was misdiagnosed and was likely fine).

if you can’t find a NOS Ford module, let me know and I’ll sell you one of mine.

The motorcraft ones are pretty expensive but I bought one from advance, hopefully it'll treat me better then the rock auto one

 

[RonD]

Welcome to TRS

+1 to all the above

If you were unlucky enough to ever own a vehicle with a distributor with POINTS then you know they required constant care, readjusting and filing them flat or replacing them, because of the AMPs they interrupted when disconnecting the coils "-" terminal

Switching to electronic "points" moved that heat and AMP flow to "transistors" in the "control module"
They still needed to connect and disconnect the coil's "-" terminal to get a spark out of the coil
Its a better system for sure but...................there is still the heat/AMP issue, but in the control module now

TFI on the distributor uses the distributor's metal as a "heat sink" to draw away TFI's heat, and as said you need a gel/grease between them so the TFI heat can be transferred to the distributors metal

Remote mounting the TFI to a cooler place in the engine bay was Fords solution to the TFI overheating
Ford use this type of TFI in later years with a heat sink: https://www.supermotors.net/getfile/832641/fullsize/idm-ignition-002.jpg

People often DIYed their own solution using current TFI, like this: https://turbotbird.com/old/techinfo/Remote Mount TFI/Remote_Mount_TFI_by_John_Klett_files/image002.jpg

 

[DarrenA]

Bit of a follow-up here. So I got my motorcraft Tfi in the mail today, while I was waiting for my kit to relocate the Tfi to come in, I decided to put the new Tfi in to take it for a quick cruise around the block. Pretty dumb of me in hindsight. I made sure to coat the heat sink part of the Tfi in thermal paste and simply reinstalled it. Checked my connections after to make sure everything is good. After that, I tried to crank it over. It took maybe 7 times trying to start the engine until it fired up. Found that strange but I let it idle for about 5 minutes before I took it down the driveway to go around the block. I made it maybe 50 feet before the engine shut off and resumed its previous no spark issue. Let’s just say I was especially disappointed in that moment after spending that motorcraft money lol. I mean the cheap Chinese one off of rock auto got me further than that. This leads me to believe that something else that is not the Tfi is causing this issue (and roasting my Tfi modules) Has anyone else experienced this? I’ve only owned the truck for 2 weeks and drove it home 2 hours without an issue besides an oil leak that I fixed. After the initial failure, I replaced the ignition coil with an Msd oem replacement, spark plugs, distributor cap and rotor, spark plug wires, and obviously Tfi module. Has anyone else experienced this or have any knowledge of how to fix this? My brother who has much more electrical knowledge then me thinks that it might be getting overvolted somehow and frying. Which would mean that relocating the Tfi module wouldn’t fix my issue. Starting to bum me out how I’ve owned the truck for a couple weeks and only really got to drive it the two hours back to my house when I first got it lmao. The 302 swap I had in mind might be happening sooner than intended at this rate.

 

[DarrenA]

Welcome to TRS

+1 to all the above

If you were unlucky enough to ever own a vehicle with a distributor with POINTS then you know they required constant care, readjusting and filing them flat or replacing them, because of the AMPs they interrupted when disconnecting the coils "-" terminal

Switching to electronic "points" moved that heat and AMP flow to "transistors" in the "control module"
They still needed to connect and disconnect the coil's "-" terminal to get a spark out of the coil
Its a better system for sure but...................there is still the heat/AMP issue, but in the control module now

TFI on the distributor uses the distributor's metal as a "heat sink" to draw away TFI's heat, and as said you need a gel/grease between them so the TFI heat can be transferred to the distributors metal

Remote mounting the TFI to a cooler place in the engine bay was Fords solution to the TFI overheating
Ford use this type of TFI in later years with a heat sink: https://www.supermotors.net/getfile/832641/fullsize/idm-ignition-002.jpg

People often DIYed their own solution using current TFI, like this: https://turbotbird.com/old/techinfo/Remote Mount TFI/Remote_Mount_TFI_by_John_Klett_files/image002.jpg

Yes I read the tech article of how to remote mount the tfi, seems like it’s definitely the way to go with these engines.

 

[pjtoledo]

I'm not a expert on the older Rangers so all I can do is ask questions for the real experts to comment on.
is there supposed to be a ballast resistor ?? can you add a ballast resistor?

is the distributor getting hot enough to fry the TFI?


long ago I did have 2 different Taurus' with the same TFI system. I've replaced a couple of 'em.

 

[RonD]

Never read of a TFI module being "fried" electrically, they just got heat sensitive and shut down or no re-start when hot

There are just 3 electrical parts
The Hall Effect sensor inside the distributor(the points), its a 12volt sensor so has a 12v wire and a ground wire, then a "signal" wire, those are the 3 connections in the top of the TFI
Its a 12v ON/OFF signal, 6 ON/OFFs as distributor does 1 full turn(for a V6 engine)

TFI module, this controls the "-" terminal on the Coil, but...........it also calculates RPM spark advance(what the springs and weights did in older distributors)
So as the Hall Effect 12v ON/OFF happens faster(RPM is going up) the TFI spark the coil sooner so spark happens 20-30deg BTDC, instead of 12deg BTDC at idle
TFI is also connected to the engine computer to get Load Spark Advance, this replaced Vacuum Advance
The SPOUT connector is the Load Advance wire, you disconnect this wire to set base spark timing

And then there is the Coil, no way to test these, they can certainly go bad, and heat is what kills them as well
Not sure a 1985 would have a Ballast resistor or Resistor wire, these were common with older Coils, they would reduce the 12volts at the Coil down to 8-9volts so they would run a bit cooler
You can test voltage at the coil with Key on, if 12v(battery volts) then no Ballast resistor

 

[DarrenA]

Never read of a TFI module being "fried" electrically, they just got heat sensitive and shut down or no re-start when hot

There are just 3 electrical parts
The Hall Effect sensor inside the distributor(the points), its a 12volt sensor so has a 12v wire and a ground wire, then a "signal" wire, those are the 3 connections in the top of the TFI
Its a 12v ON/OFF signal, 6 ON/OFFs as distributor does 1 full turn(for a V6 engine)

TFI module, this controls the "-" terminal on the Coil, but...........it also calculates RPM spark advance(what the springs and weights did in older distributors)
So as the Hall Effect 12v ON/OFF happens faster(RPM is going up) the TFI spark the coil sooner so spark happens 20-30deg BTDC, instead of 12deg BTDC at idle
TFI is also connected to the engine computer to get Load Spark Advance, this replaced Vacuum Advance
The SPOUT connector is the Load Advance wire, you disconnect this wire to set base spark timing

And then there is the Coil, no way to test these, they can certainly go bad, and heat is what kills them as well
Not sure a 1985 would have a Ballast resistor or Resistor wire, these were common with older Coils, they would reduce the 12volts at the Coil down to 8-9volts so they would run a bit cooler
You can test voltage at the coil with Key on, if 12v(battery volts) then no Ballast resistor

Potentially this Hall effect sensor inside the distributor could’ve gone out then, you think? I tested my original coil for voltage, primary and secondary resistance. Everything checked out, the only reason I replaced it was because it was rattling around in its assembly. I’ll check my new one to make sure as well.

 

[Uncle Gump]

Hall effect devices are low current. Higher amperage causes heat. I would be more suspect of that new coil you just put on.

 

[85_Ranger4x4]

Neither here nor there but I had the wrong coil on my truck and it would fry Duraspark modules very quickly.

 

[AndyB.]

1) Does the new TFI say Motorcraft on it? I would try to find a new old stock part.

2) It would be a good idea to troubleshoot. The stator in the distributor msg be the issue. To replace it you’re going to have to pull the distributor, use a gear puller to pull the drive gear, reinstall the distributor and reset timing.

 

[19Walt93]

Bit of a follow-up here. So I got my motorcraft Tfi in the mail today, while I was waiting for my kit to relocate the Tfi to come in, I decided to put the new Tfi in to take it for a quick cruise around the block. Pretty dumb of me in hindsight. I made sure to coat the heat sink part of the Tfi in thermal paste and simply reinstalled it. Checked my connections after to make sure everything is good. After that, I tried to crank it over. It took maybe 7 times trying to start the engine until it fired up. Found that strange but I let it idle for about 5 minutes before I took it down the driveway to go around the block. I made it maybe 50 feet before the engine shut off and resumed its previous no spark issue. Let’s just say I was especially disappointed in that moment after spending that motorcraft money lol. I mean the cheap Chinese one off of rock auto got me further than that. This leads me to believe that something else that is not the Tfi is causing this issue (and roasting my Tfi modules) Has anyone else experienced this? I’ve only owned the truck for 2 weeks and drove it home 2 hours without an issue besides an oil leak that I fixed. After the initial failure, I replaced the ignition coil with an Msd oem replacement, spark plugs, distributor cap and rotor, spark plug wires, and obviously Tfi module. Has anyone else experienced this or have any knowledge of how to fix this? My brother who has much more electrical knowledge then me thinks that it might be getting overvolted somehow and frying. Which would mean that relocating the Tfi module wouldn’t fix my issue. Starting to bum me out how I’ve owned the truck for a couple weeks and only really got to drive it the two hours back to my house when I first got it lmao. The 302 swap I had in mind might be happening sooner than intended at this rate.

The first thing I would do is measure the resistance of your coil, if it's too low the module will die early and often. If it's low and you really want to keep it a ballast resistor would increase the resistance, too.