I am doing a 5 spped swap in my 92 f150 i have a 95 parts truck that was 5 speed will the computer work? please help I wanna get this whole project over with I can't find anything on the subject also will my automatic trans x member work ?? the parts truck 5 speed x member is rusted thru... damn winter time salt anyhow.. any help is very much appreciated thanks
-Wendell

 

I would think No. '95 would be a MAF EFI and '92 would be Speed Density EFI.

What engine are you working on?

 

Assuming both engines were the same, and the 95 is still speed density (and not mass air) it should work.

 

Both are 300 6 cylinders sorry I should have written that and thank you guys for the help so far

 

Then if both are the I6, you should be fine. The 4.9 didn't go MAF until '96, with the introduction to OBDII.

The 302, 351 got MAF late '94 and early '95.

 

The ignition system is different on the '95, it uses Computer Controlled Dwell (CCD). The '92 uses Push-Start. There are wiring differences between the two as well as different Ignition Control Modules.

It's not a plug-n-play swap.

 

so will it or won't it work?? haha anyone with definitive info please

 

It will work but in order to be compatible with the '95 computer you will need a CCD style ICM and some wiring changes.

The ignition wiring on your 1992 looks like this:


The Start signal from the starting system is shown coming into the Ignition Control Module. This is used to increase the dwell when trying to start the engine. The IDM signal is derived by the Coil signal from the ICM, then buffered by a 22K ohm resister (Igntion Suppression Resistor).

1994 and later trucks use a CCD style igntion:


The Dwell is controlled by the computer and the ICM has an output signal for the IDM signal to the computer (PCM).

The truck may run but I would suspect some drivability issues such as lack of power and/or poor fuel mileage.

 

rla: Very informative! Your use of letter-style abbreviations is a problem for dummies like me, though. Your use of the term "dwell" means that the coil is energized for less time during cranking? It would make sense, as not re-energizing the coil as quickly allows for a more complete collapse of the primary field, thus generating higher secondary voltage, yes? But, with the eng. running, especially running FAST, there is a definite limit to how long the coil may be either ON or OFF.


I think more in terms of crankshaft position being determined by the little caged wheel in the distributor, which also identifies cyl. #1, yes? Then we process that crank position and speed information in order to tell the coil when to produce spark, the distributor cap being responsible for proper direction of high voltage delivery.


Looks to me like in the first version, power to the ICM is directed there by the ignition switch, and in the second by the PCM. If they both use the Thin Film System, as I'm sure they do, my gut feel is that either will run the ignition fairly equally. The change from Speed Density to Mass Air would make for a definite NO answer regarding PCM interchangeability. Correct me if I'm wrong! I'm always learning, sometimes the hard way! impish

 

A snip from a great article I found on the web on how each ignition system works and how it interacts with the PCM (computer):

Ford’s early TFI system, the Push
Start TFI system, uses a gray TFI
module. Originally, the TFI module
was always mounted on the
distributor. In the late ‘80s, Ford began
to relocate the TFI module away from
the distributor on some vehicles to
provide better protection from the
effects of engine heat, but system
operation remained the same. The
system 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-4 computer and the
TFI module. The EEC-4 computer
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-4 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 unique to the
Push Start TFI system is the start input
on pin 4 of the module connector,
which 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
the Computer Controlled Dwell (CCD)
TFI system on some vehicles. This TFI
module is always black. 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, output
directly from the TFI module to pin 4
on the EEC-4 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 in on 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 driveability 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-4
computer comes directly from pin 4 of
the TFI module, it is a CCD system – if
not, it is a Push Start system.


While using the 1995 PCM in a truck with a Push-Start style ignition system may "work" it could introduce new issues. Hence the reason for my opinion that other wiring may need to be changed.