Aug 30, 2018
Ontario, Canada
Hey guys I've got a serious ignition issue and at this point im just looking for other opinions

1995 Mustang GT 5.0 Bored and Stroked to 347, 5 Speed, Convertible California Car.

So this car has been an ongoing project, did the engine and have been having serious ignition gremlins since. Unknown if that car possessed them prior as it was bought and driven very little before the swap. The car now will not spark, at all. For the past few months it had been eating ignition coils and other ignition components and an ever lingering misfire while driving.

Currently on the Car
New Accel Ignition Coil
New MSD Distributor
New Computer
New Capacitor on the back of the Coil

I have personally had both the injector harness and the ECU harness that runs inside the passengers fender to the TFI out of the car, opened and inspected every inch. There was some repairs to be made but nothing too major, I swapped the Distributor connector to the Pip as the old one was rather corroded and damaged as well as the coil connector as it was tough too. Used butt connector and shrink tube to make all my connections, (It has run since I swapped the connector some im confident in those connections) that was the only alteration I made in the harnesses, re-loomed and installed them back into the car.

Now for what I know thus far in the electrical system, I am an Electrician so have a pretty decent understanding of how it operates. I have good battery voltage in my injector harness coming to my PIP in the distributor, from there on out I am not getting any flash in the signal heading to my pip. I have tried two distributors, three pick ups and have had no change. Had a brand new distributor brought in and still get no flash back heading to the TFI. I have good continuity on the wire heading from PIP to TFI, but I am not able to get the PIP to send voltage on that wire, also in that harness I appear to have lost ground on Pins 3, 6, and 2? and have rampant inconsistent voltages on one of the Pins, cannot remember at this time. My question is does the pick up require a ground to fire, is it a transistor or how does it operate. I have introduced new grounds through Scotch Locks, they don't acquire any voltage which leads me to believe I don't have a short but it still won't fire. Good power to both sides of the coil, but again I cant get the one side to flash on and off to make the coil work.

A few other strange things I have encounter, when having the car hooked to a charger while testing to ensure damn good voltage, the Alternator got surprising hot, although the engine had never turned more than 100 times. Alternator is pulled and getting bench tested tomorrow.
When back probing the TFI with it plugged in and using a test light, either from the positive or negative terminals of the battery, when I probe pin 1 I believe, it will cause the whole computer to cycle like ive turned to key to run, the Light doesn't light up in either polarity, but it will cause the computer to reset every time.

All of our grounds exist, have low continuity to negative on the battery except for block to battery see's 70-80 Ohm's

This car has seen' in the past Two Months
5 Ignition Coils
3 Computers
2 Computer Chips (Tuned by Pro Car in Akron, Ohio)
1 Stock Computer Chip (Ran, very poor due to 347 Swap)
2 Dizzy's
3 Pick- Ups
2 TFI's
2 Radio Suppression Caps
3 Sets of Spark Plug Wires
2 Sets of Plugs

Everything on the car is new, Exactly 11 Kilometers on it. It was running great went and topped it up with Premium, pulled away from the pump and it flat lined. Nothing Since.

Every Ground the internet has told me about has been triple checked, I've studied the diagrams for hours on end, read endless forums and no one has had a problem quite like this one. Literally have had two Ford Engine Engineers look at this thing multiple times and we've got everyone stumped.

Any and all Questions let me hear them, if you've got something to suggest you can bet we've tried it or something similar but i'm all ears at this point.

Only Electrical modifications done to the vehicle since it's been brought home is a stereo installed, a Ford Performance coolant temp gauge, Cluster out of a 1995 as the original had only the speedo kind of working, not at all accurate and no other gauge activity and a set of halo headlights installed. It had run since those mods were done as well.
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
polk county florida
Don't take offense to this, butt connectors and scotch locks? I'm not an electrician, hell I'm barely a shade tree mechanic but I solder and shrink wrap my connections/repairs.
Have you looked at the 'cranks but no start checklist ' in the 5.0 technical/how to forums? The 94-5 stuff is highlighted.
Aug 30, 2018
Ontario, Canada
Have read and ran through the entire check list

No two solders are alike and will yield different resistances. Butt connectors are way more consistent. Scotch locks were for temporary grounds, so no unnecessary cuts and added joints weren’t required.
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StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
Dublin GA
Do you have access to an oscilloscope? You going to need it to measure the PIP sensor output...

The following are diagrams courtesy of Tmoss & Stang&2birds
TFI module wiring for 94-95 Mustang GT

PIP problems & diagnostic info
Spark with the SPOUT out, but not with the SPOUT in suggests a PIP problem. The PIP signal level needs to be above 6.5 volts to trigger the computer to pulse the fuel injectors, but only needs to be 5.75 volts to trigger the TFI module. Hence with a weak PIP signal, and the SPOUT in, you could get spark but no injector pulse. You will need an oscilloscope or graphing DVM to measure the output voltage since it is not a straight DC voltage.

See and for verification of this little detail from Wells, a manufacturer of TFI modules and ignition system products.


Tmoss’s explanation of how TFI modules work
OK guys here is the straight skinny........If uyour TFI is gray - buy a gray one..........NOTHIN TO DO WITH AUTO OR MANUAL........

Most technicians who deal with Ford drivability and no-start problems have become very familiar with the Thick Film Ignition (TFI) system. Ford started using the six-pin TFI module with the EEC-IV computer system in 1983, and for years it remained basically unchanged.

The early TFI system, which Ford calls the "Push Start" TFI system, uses a gray TFI module. Originally, the module was mounted on the distributor. In the late '80s, Ford began to relocate it away from the distributor on some vehicles to provide better protection from the effects of engine heat, but system operation remained the same. It uses a Hall effect pickup (stator) in the distributor, which generates a battery voltage, 50% duty cycle square wave, called the PIP signal, to the EEC-IV PCM and the TFI module. The PCM processes this signal and sends out another battery voltage, 50% duty cycle square wave, called the SPOUT signal, to the TFI module. As long as the TFI module is receiving a SPOUT signal, it will fire the coil at the rising edge of that signal (except during engine cranking, when SPOUT is ignored) and the vehicle will run with the amount of timing advance commanded by the computer. If the TFI module does not receive the SPOUT signal, it will fire the coil at the rising edge of the PIP signal, and the vehicle will run at base timing. This is true on all TFI systems.

Ignition dwell with the Push Start (gray module) system is controlled by the TFI module alone, and increases with engine rpm. The Ignition Diagnostic Monitor (IDM) signal on a Push Start TFI system comes from the coil negative circuit and is filtered through a 22k ohm resistor to pin #4 on the EEC-IV computer. The computer monitors this circuit to verify a coil firing for each PIP signal, and sets codes if it sees missing or erratic signals. Another feature that is unique to the Push Start TFI system is the start input on pin #4 of the module connector. This is wired into the starter relay trigger circuit, and signals the TFI module that the engine is cranking. When the module sees battery voltage on this circuit, the SPOUT signal is ignored.

In the early '90s, Ford began using a different TFI system on certain vehicles -- the Computer Controlled Dwell (CCD) TFI system. The TFI module on CCD TFI is always black in color. There are a few major differences between the two systems. As the name implies, with the CCD system, the computer controls primary dwell. The CCD TFI module still ungrounds (fires) the coil at the rising edge of the SPOUT signal, but now the falling edge of the SPOUT signal (which had no meaning to the Push Start TFI module) is used by the CCD TFI module to ground the coil. The PIP signal remains the same 50% duty cycle square wave, but SPOUT signal duty cycle varies according to how much dwell is desired by the computer.

Another major difference between the two systems is the IDM circuit. Pin #4 on the CCD TFI module, which was the start circuit input on the Push Start TFI module, is now the IDM signal, sent directly from the TFI module to pin #4 on the EEC-IV computer. This signal is still a filtered (low voltage) version of the ignition primary waveform, but is filtered internally in the TFI module rather than through an external resistor. There isn't any start circuit input to the CCD TFI module; the module infers engine cranking from a low rpm input from the PIP signal.
Since these two TFI systems are so significantly different, yet so similar in appearance, parts application problems will inevitably occur. A gray Push Start TFI module will plug right into a CCD system, and vice versa. To make matters worse, parts books are often incorrect on TFI module applications! With the incorrect TFI module installed, the vehicle will run, but drivability and MIL (malfunction indicator lamp) problems will result. For instance, if a gray Push Start TFI module is installed in a CCD system, the computer will not be able to control ignition dwell, and the MIL will illuminate with memory codes for the IDM circuit set, as the gray TFI module is incapable of generating an IDM signal to the computer. If a black CCD TFI module is installed in a Push Start system, dwell will remain fixed, since the SPOUT signal duty cycle never changes. If in doubt about which TFI module belongs on a particular vehicle, consult the ignition system-wiring diagram for the vehicle. If the wire going to pin #4 on the EEC-IV computer comes directly from pin #4 of the TFI module, it is a CCD system. If not, it is a Push Start system.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring; Everyone should bookmark this site.[/b]

TFI module wiring for 94-95 Mustang GT

Complete computer, actuator & sensor wiring diagram for 94-95 Mustangs

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs

Complete computer, actuator & sensor wiring diagram for 88-90 Mass Air Mustangs

Ignition switch wiring

Fuel, alternator, A/C and ignition wiring

O2 sensor wiring harness

Vacuum diagram 89-93 Mustangs

HVAC vacuum diagram

TFI module differences & pin out

Fuse box layout

Mustang 5.0 Lights and Radio schematic, by TMoss:

87-92 power window wiring PowerWindowWiring.gif

93 power window wiring

T5 Cutaway showing T5 internal parts

Visual comparison of the Ford Fuel Injectors, picture by TMoss:

Convertible top motor wiring

Engine mounted fuel injector harness

Location of the TPS, IAB, and the 10-pin connectors on a 5.0, picture by TMoss:

Starter circuit

Alternator diagram for 94-95 Mustangs.


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Aug 30, 2018
Ontario, Canada
Will take have a new TFI and will run through that provided list of test on the Harnesses again, I confirmed most but there is a few I didn’t try, which who knows could be my issue.

I appreciate it, I’ll see if I can’t secure a scope aswell.