Electrical TFI question 90 foxbody

Sean Canney

Member
Mar 12, 2022
55
1
8
Howdy! On my 90 5.0 foxbody the TFI calls for a coil ground where the wiring loom cobra 75 has an IDM wire ? What do I do in this situation? I was told it was wired right and to just do what the tech says by RFs tech guy. Well I did and it won't start. Help? Lol
 
  • Sponsors (?)


CAMTWO1070

Active Member
Dec 17, 2021
147
43
38
Before I had my Ron Francis debacle and blew a slew of TFI modules when I put all diode suppressed relays in the EEC and FuelPump also diode Suppressed starter solenoid in my F250 I put an Accel TFI Module at 300k when I did the T-chain and waterpump and it stayed there for 16yrs and I even deleted the factory clutchfan and put an electric fan....

This module worked like a champ for 16yrs until I hooked it up to RF's TDZ-75 harness and it became history in 5 on and offs of the keyswitch................

IMG_20180219_143205056 (2).jpg


Everyone thinks the TFI modules fail from heat...They dont...They fail from being shocked to death by Flyback...........I had my burnt out TFI modules tested and they showed Zero signs of heat fatigue and Infinite signs that point to the unit being fed too much high current and Flyback emits over 400volts back into the electrical system when the solenoid or relays electromechnical field collapses...........

Diodes are what fixes flyback which protect the system from being stungunned to death.............

In 1995 Ford Recognized Flyback and started putting Diode protected relays in their EEC and FuelPump relays but failed to put one on the starter solenoid which wasnt as severe as having all 3 unprotected...Some will argue they used a different processor chip and that reduced the heat but like I said the TFI modules I had tested showed Zero signs of heat fatigue which would cause the plastic case to warp and melt....

After putting diode protected relays in the relay block and a diode protected starter solenoid Ive had Zero issues with my TDZ Harness to date but then again I also suppressed alot of r/f interferrence that is emitted throughout the whole harness and the noise causes the sensor readings to fritz out....

I fixed that issue with Ferrite Choke beads in different sizes....I put 4 choke beads per each fuel injector wire wrapped then in copper foil tape then wrapped them in harness wrap and I put one ferrite choke bead at each power feed wire for each relay and one on the main power wire aswell as the negative to the head....

On my upgraded 170 amp alternator I put a 200 amp NewMar Noise remover between the alternator and the battery and now when I do a data log the noise and lil anamoly spikes are so minimized they are rarely found anymore whereas they turned up quite often prior....

I also put them on the TFI module wire harness, The TPS wires , The coolant temp sensor wires and the IAC too................

I got the Ferrite Choke beads from Amazon...60 pcs of assorted sizes for $20.00..Theyre designed to absorb the noise...As a tradeoff they generate a lil heat but its negligeable...

Im glad to hear you got it fired up.....Thats the first step.....Ironing out the gremlins is next........Take care SC

IMG_20220228_170421.jpg
 
  • Informative
Reactions: 1 user

Sean Canney

Member
Mar 12, 2022
55
1
8
Thank you ! I got it started and it now runs like do do. I'm so sick of it. I'm ready to start yanking wire. I pulled dizzy and re stabbed it and I KNOW I did it right and still it's bucking and runs like its 180 out. Grrrr!
 

CAMTWO1070

Active Member
Dec 17, 2021
147
43
38
Ive been where you are and had that same disgust..I pulled my harness out 5 times........It took me about 3 months to get it totally ironed out...

In my angst I made a RipOff Report on Ron Francis and Scott Bowers too...I figured whats a better way to stick it to them than educate the consumer on their shoddy wiring practices and lack of real customer service and zero business ethics..

First trace the EGR and the Transducer circuits....Mine were hooked up wrong as thats where they put the EPA cheater device..They hooked up 3 resistors that were shaped like the flux capacitor in BtTF

Like I stated earlier theres factors involved with the harness....

First is the TFI start PURPLE wire.... It must be hooked to the wire that triggers the starter solenoid.. If its hooked to a constant power source youll get a rev limiter effect and you wont rev any higher than 3k...........Its designed to retard ignition timing when engine is cranking...

The other factor is the type of transmission you selected....If your harness was designed for standard by the idiots at RF or vice versa and you selected the wrong pinout on the plug you must get an 02 retrofit harness that allows the 02 sensors to work right.

Another thing was my MAF their crappy wiring blew out my 77mm ProM MAF I had to change up and go with a 90mm Ford Lightning MAF anyways..

Another factor is how youre tapping your power and grounding your engine block...

I ground the battery and frame directly to the engine block plus I run a ground back to the starter...I also ground the battery to the headder panel...

If youre using the old yellow power wires to power the harness and the fuelpump sometimes the fuseable link can limit power from being old.....I eliminated my fuseable links and put 40amp resettable circuit breakers.....

The ground for the harness must go to the cylinder head only..........

If youre running a non computerized camshaft youre going to need to have your ECU tuned with a chip and if youre not running the right tune strategy youll need a chip also....

What code computer did you have your harness built for...? I had mine built for an A9L computer which is a manual transmission computer..

A pretty solid tip in setting the TDC is using a small whistle with a piece od 5/16" fuelline threaded into cyl #1...when the whistle blows and stops youre at TDC..............

Good Luck