I have an 89 F250, 302. I have no spark coming out of the coil. The coil ohms out good. Harness checks out good. I have a feeling it is the TFI module. I would like to pin out the TFI plug, to make sure I have what I need there. Does anyone have the pin readings that I should expect with the key in the run and start position? Also, any way to troubleshoot the TFI module. Any help would be appreciated.

 

The post below is from a web page that has a dead link and I can not find it on the net anymore.
I believe the Author was P Booth.


PART 1

INSPECTING THE TFI MODULE and Hall Sensor

The A1A (top) and A2A (bottom) Thick Film Ignition (TFI) Modules. Both are for the EEC-IV distributor. Estimated cost for a TFI Module is $100.00, plus you will need a 7/32" distributor tool illustrated below. The Hall sensor cost around $40.00, but requires a press to remove and install the cam gear.

http://i54.photobucket.com/albums/g91/subford/Electrical/Ignition/TFI%20Test/tfimods.jpg
http://i54.photobucket.com/albums/g91/subford/Electrical/Ignition/TFI%20Test/t3.jpg

Yeah, thats right. Two different part numbers. Also, a different feel to power production too.
No, they are not lot numbers as many have thought. As you can see below, the ohm resistance is different between the two. By the way, I have tested 4 different TFI modules. Both A1As measured exact resistances, as well as the A2As. The difference was around 0.11kohms, or
110ohms. Interesting, huh? It is my belief that since the resistance is applied to the hall sensor's measurement of position, this would most likely affect ignition timing artificially. I have found the A2A module results in more response to light throttle, while the A1A kicks some tail on top end.

http://i54.photobucket.com/albums/g91/subford/Electrical/Ignition/TFI%20Test/a1aohm.jpg
E3EF-12A297-A1A http://i54.photobucket.com/albums/g91/subford/Electrical/Ignition/TFI%20Test/a2aohm.jpg
E3EF-12A297-A2A

Where is the TFI mounted? Its mounted on front of the distributor and plugs into the EFI harness from the computer and connected to the Hall Sensor on the distributor end. The Hall Sensor is mounted inside the distributor and its bound by the distributor shaft and octane sensor. The Hall sensor connector is also mounted in the distributor and is reponsible for transmitting magnetic pulses to the TFI module indicated crank location.
http://i54.photobucket.com/albums/g91/subford/Electrical/Ignition/TFI%20Test/tfi.jpg
TFI Mod
http://i54.photobucket.com/albums/g91/subford/Electrical/Ignition/TFI%20Test/tfiplug.jpg
Hall Sender Connector
http://i54.photobucket.com/albums/g91/subford/Electrical/Ignition/TFI%20Test/hallsend.jpg
Magnetic Hall Sending Unit
to TFI Connector

What are the expected test ranges for TFI modules? Well, first lets reference the pins as A, B, C, and 1,2,3,4,5,6. REMOVE the TFI module, then we can measure resistances. If you attempt to measure resistances otherwise, you will get interference from the Hall Sensor. Reference data courtesy of Ford Fuel Injection and Electronic Engine Control, by Charles O Probst.

A = Ground
B = PIP Power, Profile Ignition Pickup Power. Powers the Hall Sensor in conjuction with terminal A, the ground
C = PIP IN, Ignition is picked up via the Hall sensor by rotation of the camshaft/crankshaft. This signal is sent to the TFI module.
1 = PIP, Profile Ignition Pickup. PIP signals the EEC of the cranshaft position.
2 = SPOUT, Spark Output Signal from the EEC module. This is how EEC controls your timing
3 = START, Battery voltage input with ignition switch in start position
4 = TFI PWR, Battery voltage input with ignition switch in run position
5 = TACH (IDM), Tachometer, Ignition Diagnostic Monitor, Switched output to ignition coil. Power from SPOUT signal is routed through the TFI and to this pin->coil->rotor cap.
6 = IGN GND, Ground.

http://i54.photobucket.com/albums/g91/subford/Electrical/Ignition/TFI%20Test/tfi_view.jpg

PINS EXPECTED VALUES A1A(100kmiles usage) A2A (10miles usage) % diff
NOTE: 14.26kohms = 14,260ohms

A to C > 500ohms 14.26kohm 14.15kohm -0.77%
B to C < 2,000ohms 1.112kohm 1.115kohm +0.27%
B to 4 < 200ohms 84.7ohm 86.1ohm +1.65%
A to 6 < 2ohms 0.0ohm 0.0ohm 0.0%
C to 1 < 200ohms 101.2ohm 100.8ohm -0.40%

If any of these are out of spec, you are also out of luck with your TFI module. Get a new one.

Notes: I have personally experienced a failed Hall Sensor. This part was very difficult and obscure to track down. It took one year of problems to finally track it. Trends I noticed were the following: The car would just stall for no reason and would not start for maybe 5 to 10 minutes. Sometimes, it was just difficult to start. It seemed oversensitive to humid weather and died a few times in the rain.
The car would intermittently lean backfire or start running poorly. In one case, it backfired several times one night, at which time, I got really aggressive at tracking the problem. Replacing the TFI module is a 5 minute deal, but changing the Hall Sensor requires removal of the distributor and a shop to press the cam gear on and off.

 

PART 2

TESTING THE MAGNETIC HALL SENDING UNIT.


Note that I have completely dissasembled the half-moon

TFI to Hall Sender plug connector
http://i54.photobucket.com/albums/g9.../hallsens2.jpg

Connector between Hall Sending Unit and TFI Module that mounts to the distributor wall. It is directly plugged into by the TFI module. It serves no purpose except to allow transmission from the Mag Hall Sending Unit to the TFI in a shielded manner. Remember that the Hall Sending Unit Ignition Magnetic Pickup or Hall Sending Unitis essentially an electronic set of points. It sends an Magnetic Ignition Profile Pickup (PIP) signal to the EEC-IV for each cylinder fire, then back to the SPOUT connector to the TACH(IDM) output pin, to the coil, to the rotor cap.

http://i54.photobucket.com/albums/g9...t/hallsens.jpg

Like the TFI, there are three wires, A, B, and C. If A is ground and B is power, then C better send a PIP signal back to the EEC-IV else the sender is bad. Problem is, I have seen this sender intermittently fail. When it does, the car will run choppy as if it is not timed well or may just stall and not run at all, yet suddenly crank and run fine. It can be a difficult problem to trace unless you really take the time to analyze the electronic parts. It took me over 1 year to track the sensor as bad on my car. I simply refused to believe it was bad, and after all the TFI hype, thought it must have been my TFI module. (See testing above).

Here is how you can test the Mag Hall Sending Unit:

1. You must determine if a PIP signal is evident. This can be accomplished by checking the voltage from the PIP signal. It should be from 3 to 6v if using a volt meter. Or you can use a test bulb and should see blinking.

2. The connector should be plugged up and then you should connect the positive lead of the volt meter to the #1 pin (the top one) on the connector. You will have to either use a splice connector or remove a small area of the insulation on the wire as I did to get to it. Then connect the ground to any ground. I used the battery ground. Oh, the top wire is dark blue in color.

http://i54.photobucket.com/albums/g9...est/tfipip.jpg

TOP TFI Pin->Dark Blue. This signal is from the Hall Sending Pickup

3. Start the engine and watch the voltage. It should be 3 to 6v or a blinking light if you choose to test via that method. The bulb blinking method is easier. I used a digital volt meter only to find the voltage was steady on crank up, then jumped around a bit. It seemed to pulsate.

http://i54.photobucket.com/albums/g9...%20Test/v1.jpg
http://i54.photobucket.com/albums/g9...%20Test/v2.jpg

Voltage on TOP TFI Pin to Ground. Test of PIP and Hall Sender Voltage on TOP TFI Pin to Ground. Test of PIP and Hall Sender


4. If all else fails, remove it and replace it. I have to finally do this. When I did, I discovered the new sending unit had 0 ohms, while the bad one had around 15,000ohms between poins A and C.

 

One thing you can try is taking it to autozone and let them put the module on their tester. If it's an intermittent problem, they still may not pick it up, but you may not either by doing your own test.

You can also read the codes from the engine computer. It monitors some of the signals from the dist, and if one goes missing, it will put out an error code.

 

Autozone sounds easier. This ignition is dead. No intermitent at all, dead dead.

 

You may want to consider our F-150 Firepower Ignition-Click on this link and scroll down:

http://www.performancedistributors.c...50ignition.htm