Bad TFI's???
 

Anybody had a bad TFI?
I am trying to isolate an apparent ignition related problem at WOT.
I am looking for symptoms and solutions. Thanks.

bad module
 

I had a bad tfi module on my 95 right before i sold it.It would stumble while a a cruising speed,not want to start sometimes ,and backfire on the 1-2 speed shift.I went to autozone and they have a module tester and tested it(I actually had to show the guy how to use it but hey they did have one) and it was bad .They have a low rpm side and a upper rpm side mine was bad on the upper and lower,go figure lol!

No S**T???
 

No kidding? I have a Mallory aftermarket distributor and I think it is crapping out. I have had it for 3 years. I have a totally unexplainable miss and have swapped everything else. Plugs, new wires, new coil, triple checked grounds, cap, rotor. etc...It has been very frustrating and is probably the cause of a crappy dyno run this week.

just out of curiousity.....
 

Hey, I was wondering how much those TFI modules are and how hard are they to replace.
On my '88GT it sometimes stumbles at cruising speed like yours did and last summer it left me sit while come home from vacation.
It was a hot day and wouldn't start again until the engine cooled down a bit. It hasn't done that since then but it does stumble sometimes and I think it's just going to quit one of these days.
I was told that these modules are notorious for failing and Ford had a recall on them.

textbook...
 

you have just described a possible textbook TFI module malfunction. Summit carries an OEM replacement by mallory for 53 bucks. takes 3 weeks to get it.

Auto Zone Wells TFI 29.99 comes with lifetime warranty too!

TFI TROUBLES
 

I have had a few TFI's go bad on me in the past...

I ran a Performance Distributors Screamin Demon ignition kit (bought it in '98 and ran it for about 2 yrs.) It came with a coil, brass term. cap and rotor, cool plug wires, and the infamous TFI module... It was alright for some time, but one day my car would turn over and not fire. I checked it all over, got spark at the coil but not at the plug, etc. Finally after reading, checking, and process of elimination, I discovered it was that damned TFI module. They covered the first one, but soon after I had to replace it again and was so frustrated that I replaced it with a Wells stock/factory TFI. Couldn't tell any difference in power...

And I recall a few times where my car had stalled at various places, waited around awhile (sometimes longer than others), scratch my head, check connections, etc., and FIRE! rumpity-rump away I go!

TFI modules are FUN... I look forward to replacing one in the future... Make sure when you replace your TFI that you use the silicone di-electric compound on the backside.

I don't believe I have ever encountered an erratic ignition/misfire because of a TFI, usually the car doesn't get ANY fire...
(in my experience anyhow)
Take care... and good luck:)

BTW, the MSD billet distributor I bought in 2000 that I thought the TFI would be good/better because of the neat little MSD sticker on it...

WRONG!!!

I have replaced that one once already!!:D

I think they get too hot and burn up/out (???)

Must be why they relocated them to the fender in the 94-95's

Yep, you're right.
 

My 4800 hesitation/misfire(?) is still there. I've done everything simple now.
Now I have to take the intake off and check injectors, etc.

If you still have your stock distributor, try it out...
Make sure you're not one tooth off or 180 out. It's worth a try before you pull the intake, etc.

Sounds to me like something electrical/ignition related, though I am as baffled as you seem to be. What are you going to do to check the injectors? Have you swapped out the coil with a stocker to see if that make any difference? What about the MAF sensor?

Wish I could be more help!

I apologize for not being "all-knowing"
Just making a suggestion, that's all...

I have a very simalar prob.
 

I have a miss at idle til about 2,000 rpm's. Ive tried everything mentioned here. still have it. it's so bad I can't drive my car

f-ing injectors...
 

I bought the injectors used off of e-bay.
They sat out for 6 months while I built my long block so that's next on the troubleshooting tree. There is a race weekend next weekend and I want to be ready for my run. I have 5 days to fix this.
First, pro injector clean.
Next, if not luck, injector swap to 30#'s and a new MAF.
Worst case, bad cam.
Then a custom ground unit.

Best case $500
Worst case $1500

340 NA hp by July.

"I love the smell of Napalm in the morning. It smell's like..Victory."

On my 82GT I have a Mallory distributer(series 37) I bought because it eliminated that ignition box on the fenderwell. I had to replace the module on that already but a module for one of those distrubuters is $90....oooouch!!

Typical symptoms of a TFI module failing include a no-start/hard-start condition when warm (pull into the gas station to get gas, and it won't start for 15 minutes).

A coil that is starting to go tends to cut out at higher rpms.

The problem I'm reading about here sounds like a misfire problem caused by having the #5 and #6 spark plug wires too close together. It is very important that they do not touch each other at all, from leaving the distributor cap all the way to the spark plugs. This applies to all small block Ford engines, except that for non-HO 5.0's, the wires to worry about are #7 & #8.

Take care,
-Chris