what would be symptoms for a bad tfi? My truck ran great and now won't start. Can it be tested? I have a real weak spark so i replaced the coil and it's no better. I pulled it off the fenderwell, what size socket will work to seperate it from the heat sink?

Thanks i miss driving my truck.

 

You are experiencing the most common symptom of tfi failure.Yes it can be tested.Most large chain parts stores (Advance, Auto Zone, ect) can do it for you.The socket you need is 5/32". Check the parts stores as there is a neat little tool for this.Hope this helps.

 

cool, i tried a 5/32. It doesn't fit down in the recess area to get on the head of the bolts to remove it from the heatsink. I tried a deep well 5/32 and it didn't fit. I'll check in town after work, and get a cheap socket and grind it down if needed. so now is ford's worth the 85 bucks or 53 from autozone.

 

I'd go the Ford route myself.There is some high quality aftermarket stuff but I'm not familiar with what Auto Zone carries.The little tool I mentioned is a thin walled socket with a spinner **** on it.I think mine was made by Thexton.

 

thanks, will post results...

jason

 

Whats a tfi

 

toddol1971 , tfi is the ignition module. If my memory is correct it stands for Thick Film Ignition system.

 

why not call it the IM then LOL. Thanks.

 

If there is any question as to the functionality of the TFI just hook up a Ford Rotunda TFI-IV Intermittant Ignition Anlayzer. That thing will tell you everything you need to know. It installs in series with the module and you can see in "real time" what is going on and it comes with a manual that will help you troubleshoot if help is needed.

 

Thick Film Integrated ignition module