any you guys have experience with what a piece of crap they are and the symptoms?
i've got an '85 crown vic. 5.0 with tbi.
47k original miles. looks the part. anyways...
runs good cold. as it warms up the idle quality gets worse. if you run it on the highway for an hour it wont idle at all. always restarts immediately. runs good off idle all the time. i checked fuel pressure, unfortunately while the motor was cold, but it was rock solid 40 psi regardless.
spark plugs looked new from a wear standpoint. they had a little faint brown haze, and just enough metal flake on the ceramic to notice.
wires say "motorcraft 1985" on them. cap/rotor look like they're O-OEM as well.
it was my understanding that a bad tfi would just stop all together until it cooled off. ever seen one just work poorly when hot. and only at idle?
They are heat sensitive, I have seen them degrade but not in the manner you are describing.
I would replace it anyway as well as a fuel filter, plugs wires cap and rotor and Motorcraft PCV valve.
The guy's over at the mini stock furum @ 4M.net say they can do as you discribe they also say all aftermarket units fail quicker then OEM at least in 2.3 that spin 8000rpm. So go as far to recomend junk yard OEM units over wells or standard brand.
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Performance Distributors sells a "hot" version that's pretty good. Find a real Motorcraft one, use new cream on the backside, and call it good. If you still have problems you can find the uber-rare Ford remote-mount heatsink base and re-wire. I happen to have one of those... It's also for sale... 
ugh.. I remember my uncle's ford van and it's problems with that. At least the dizzy in that car is easier to access
Raze
Reader
8/27/09 7:12 a.m.
OK, TFI lesson: sensitive to heat and vibration, on our 2.3T the TFI module is located on the hottest vibrator on the car (dizzy). We've had 3 fail or intermittently fail, 2 when hot/higher rpm, 1 cold, here's the most effective diagnostic routine:
Step 1: remove the (cold) TFI module and perform the resistance test: http://www.geocities.com/MotorCity/Flats/3349/test.htm if any of the values are out of range replace the module.
Step 2: remote mount the TFI module onto a heat sink (Ford later figured this out and did thusly): http://www.therangerstation.com/tech_library/remote_tfi.htm, I would put in on the firewall or fender, not near the radiator which could heat soak it.
Step 3: You should be able to do this for next to nothing, if you have the time you can get old TFI modules from the junkyard for dirt cheap (Motorcrafts are better than Chinese made AutoZone parts from experience) and you can get a heat sink for a few bucks too, get some decent gauge wire and some spade connectors and you're in business...
Welp, that appeared to be the problem. I also did the wires/cap/rotor at the same time. runs like a new tbi 5.0.
eww... sorry to hear about that. Better luck next time.
ha-haa.
can't wait till the owner gets tired of this car so I can buy it for a song.
RossD wrote:
What does TFI stand for?
I am glad you asked it. I figured I was the only one that didn't know. Still don't know what it is but I am making a mental note to never buy a car that has one.
they're $40 with a lifetime warranty
