• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

How to test TFI module & Stator in Distributor

mattt

Bronco Guru
Joined
Sep 23, 2006
Messages
3,810
I have an EFI no start issue issue....no spark or injector pulse from what I can see. How do I verify that the TFI module and the stator inside the distributor are good? If I understand correctly, the stator is where the computer gets the rpm signal to know the engine is running and for cylinder ID purposes. I had this factory distributor rebuilt locally and the builder supposedly installed a new stator assy during rebuild. The rebuilder had no way to check the TFI module. What is the test procedure for a TFI module(distributor mounted) and stator?
 
OP
OP
M

mattt

Bronco Guru
Joined
Sep 23, 2006
Messages
3,810
I heard thru the grapevine that Autozone has the ability to test TFI modules, so I took it in. The module was still mounted on the distributor, but they hooked it up to the test box and it came out good. No way to test the stator down in the distributor there....is there a way to test the stator?
 

HGM

Sr. Member
Joined
May 24, 2010
Messages
973
Loc.
Senoia, Ga.
At the dealer, back in the day, we had a tester that would show the pulse. But, in all practicality, most tech's had a "known good" distributor to plug in and test. Essentially, plug it in, spin it and look for a spark.. If you had spark on the test unit but not on the vehicle, you replace the module and stator. We never peice-meal'd it, both components or none.. The older systems were not very diagnostic freindly.. Lots of trial and error.. Huge part of my decision to go OBDII on mine..
 

Steve83

Bronco Guru
Joined
Jul 16, 2003
Messages
8,980
Loc.
Memphis, TN, USA, Earth, Milky Way
What was the donor vehicle for your engine/ignition? Get a Haynes manual for that vehicle & follow the ignition diagnostic.

BTW
The PIP doesn't perform cylinder ID; EEC-IV doesn't have that capability. The PIP only reads timing & RPM. The injectors open semi-randomly, but the spark is timed to the correct cylinder by the distributor orientation & plug wires.
 
OP
OP
M

mattt

Bronco Guru
Joined
Sep 23, 2006
Messages
3,810
The donor vehicle is a hodge podge of parts. Mustang 5.0 computer(a9l) and harness, 94 351w engine, distributor from 91 E van w/ 5.8 and attached TFI module. I also swapped gears and had this distributor rebuilt to be compatible with the roller cam.

What I meant by the stator aiding in cylinder ID is the same as you said Steve....Since #1 is a fixed position in the distributor, and the hall sensor triggers when each cylinder is to fire, that is how the system triggers spark and injector pulse.

I should re-title this thread to read....new EFI, no spark or injector firing.

I have done all the checks/tests here on the wiring... http://fordfuelinjection.com/?p=44
All resistance & voltage checks are within the parameters. I've also pulled codes, KOEO..only ones I have are 81 82 84 85. No KOER codes yet, it won't fire.

I have a noid light on one of the injector plugs, no flash. Also put a spark plug on coil wire and turned over...no spark.

I read a reply that bowsher posted in one of the MANY threads I searched and read, he said something to the effect of with everything good, if the distributor doesn't send a signal for rotation(rpm) and reference point(which cyl), the whole computer, ignition just sits there and does nothing. I'm paraphrasing in my layman's terms what I read....so if I don't have the terminology correct, forgive me ahead of time. What I'm experiencing seems to be that exact scenario. What to check next?

Unfortunately I don't have another distributor that I can pop in to check. I thought I was very thorough in my install and expected it to fire on the first try....but no such luck. I'm trying to eliminate items from the "cause" list.
 
OP
OP
M

mattt

Bronco Guru
Joined
Sep 23, 2006
Messages
3,810
One other possible issue that I noticed in another thread is at the bottom of Post #11 by Bronko69er in this thread, http://classicbroncos.com/forums/showthread.php?t=126354&highlight=EFI+spark

Instead of running the run power wire over to the brown wire on the old "I" post, I tapped into circuit "#16" right at the red factory 3 wire connector on this diagram, h t tp://seabiscuit68.tripod.com/images/68-71ignition-color.gif

The pink resistor wire is still in my Bronco. I asked about this exact issue in another thread a few weeks back and VW made it sound like it was OK even with the pink resistor wire in place. I'm not taking a dig with that....just looking for further clarification since someone else before me has had possible issues with this configuration.
 

HGM

Sr. Member
Joined
May 24, 2010
Messages
973
Loc.
Senoia, Ga.
Dumb question, but, have you verified that the rotor is turning? I've seen the gear spin on the shaft.
 
OP
OP
M

mattt

Bronco Guru
Joined
Sep 23, 2006
Messages
3,810
Not today....but a few weeks back when I first turned it over with the key and watched for oil pressure on the dash. The distributor was in, but cap not on, I saw it spinning.
 

Bronchole

Bronco Guru
Joined
Mar 24, 2004
Messages
1,611
Loc.
Chatsworth, Ca (LA)
In the long run of things you should be carring a spre TFI module and the little wrench it takes to change it. Go by one now and swap it in and see what happens. These things can be bad right off the shelf. When you buy it have it tested right at the auto parts store. As mentioned earlier, Autozone can test these and I suspect that Oriely can also. Be warned, sometimes they will test ok, but after they get warm during operation they start to do funny things.

Check with the brotherhood local to you (SoCalBroncos) and see if anyone has a spare distributer laying around that you can use to test with. 351/302 and gear type don't matter for this, it just needs to be a distributer mounted TFI. I do not know if the body of the distributer needs to be grounded to the motor, but all you need to do is hook up your TFI plug to the distributer and rotate the shaft while checking for spark from the coil.
 

Steve83

Bronco Guru
Joined
Jul 16, 2003
Messages
8,980
Loc.
Memphis, TN, USA, Earth, Milky Way
KOEO..only ones I have are 81 82 84 85.
What are the complete definitions for each of those?
...if the distributor doesn't send a signal for rotation(rpm) and reference point(which cyl), the whole computer, ignition just sits there and does nothing.
Right, except there is no reference point. When the dist starts spinning, neither the EEC nor the ICM know which cylinder it started on, or which cylinder is being fired. They just fire. Eventually, there's enough gas sitting on an intake valve for that cylinder to fire when it gets a spark. The ICM never knows which cylinder is firing - it just pulses the coil in time with the PIP, and the spark goes to the dist, which sends it to the cylinder coming up closed.

But if there's no PIP signal coming out of the dist, the ICM has nothing to work with - it thinks the engine is stopped. The EEC shares the PIP signal, which it uses to calculate timing advance & injector pulsewidth, but it never knows which cylinder is being fired, if any. And again: if there's no PIP, it assumes the engine isn't turning. So it all depends on the PIP sensor in the distributor.
I do not know if the body of the distributer needs to be grounded to the motor...
Yes, definitely, on virtually all Fords, the ignition system ground is the distributor body, which needs to be electrically grounded.
 
Last edited:
OP
OP
M

mattt

Bronco Guru
Joined
Sep 23, 2006
Messages
3,810
Codes... http://fordfuelinjection.com/index.php?p=48

What are the complete definitions for each of those?Right, except there is no reference point. When the dist starts spinning, neither the EEC nor the ICM know which cylinder it started on, or which cylinder is being fired. They just fire. Eventually, there's enough gas sitting on an intake valve for that cylinder to fire when it gets a spark. The ICM never knows which cylinder is firing - it just pulses the coil in time with the PIP, and the spark goes to the dist, which sends it to the cylinder coming up closed.

But if there's no PIP signal coming out of the dist, the ICM has nothing to work with - it thinks the engine is stopped. The EEC shares the PIP signal, which it uses to calculate timing advance & injector pulsewidth, but it never knows which cylinder is being fired, if any. And again: if there's no PIP, it assumes the engine isn't turning. So it all depends on the PIP sensor in the distributor.Yes, definitely, on virtually all Fords, the ignition system ground is the distributor body, which needs to be electrically grounded.
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,316
BTW
The PIP doesn't perform cylinder ID; EEC-IV doesn't have that capability. The PIP only reads timing & RPM. The injectors open semi-randomly, but the spark is timed to the correct cylinder by the distributor orientation & plug wires.

That may be true for the batch fire (truck) motors but it is not true for the sequential fire (mustang) motors. There is a unique gap on the PIP wheel to ID #1. The motor has to spin a couple revolutions during cranking for the ECM to find the #1 PIP signal. That has the added benefit of letting the oil pressure come up some before firing.

This could be part of the problem. A '91 van distributor would not have the unique PIP identifier. A '94-'95 351W distributor would.
 
OP
OP
M

mattt

Bronco Guru
Joined
Sep 23, 2006
Messages
3,810
That may be true for the batch fire (truck) motors but it is not true for the sequential fire (mustang) motors. There is a unique gap on the PIP wheel to ID #1. The motor has to spin a couple revolutions during cranking for the ECM to find the #1 PIP signal. That has the added benefit of letting the oil pressure come up some before firing.

This could be part of the problem. A '91 van distributor would not have the unique PIP identifier. A '94-'95 351W distributor would.


Interesting take.....I just went out and looked at the windows on the wheel inside the distributor. There is one window a little wider than the other 7, and it corresponds with the rotor. I never thought about the 91 vintage distributor being batch fire, but it should have been, whereas the Mustang is sequential and requires proper cylinder ID to work optimal.

In any case....I'm not re-inventing the wheel with this collection of parts. I know there are others who have done 351 efi with a distributor mounted TFI module. In ~92 TFI's went remote, as would the 94-95 be. From what I read, this is the correct distributor to use for 351 efi and distributor mounted TFI with Mustang electronics.

I found a test for the stator online at http://351winsor.com/joel/Ignition_Systems/tfi2.html

I just tried the test with a paper clip in the correct wire(dark blue #1 on TFI plug), turned the engine over and I had less than 1v coming from that location. So I then tried the light bulb test...no blink at all. I dont know if the bulb I used would even light with 3-6v, but it's what I had....it is the brake warning light from a Bronco dash. It's looking like I'm getting no PIP signal, but I'm going to check my work and test again.

Suggestions....I'm all ears!
 
OP
OP
M

mattt

Bronco Guru
Joined
Sep 23, 2006
Messages
3,810
Tested the stator again....figured it out. Woo Hoo!

The stator in my distributor is dead, not sending a signal to the ECU for firing injectors and plugs. The shitty thing about this is there is a brand new stator in this distributor.....I had the distributor rebuilt earlier this year and bushed top and bottom. At that time, the rebuilder suggested putting a new stator in since the distributor was all apart anyway. It appears to not be a Ford stator...dead out of the box. I already talked to the rebuild guy and he is going to replace it again, with a Motorcraft part this time!

How I figured this out was by scaring the crap out of myself inadvertently. I have a random EFI distributor here, so I hooked it up to the harness plug, grounded it to engine, and spun it by hand. Bam!....lots of clicking(injectors) and lots of flashes(noid). I wasn't expecting it so when it all went off it startled me....nothing like Jerry rigging something up, standing over the engine and being bombarded by flash and click. Hope to have the distributor squared away tomorrow and on to the next one. Thanks to all who took the time to offer suggestions and pointers.
 
OP
OP
M

mattt

Bronco Guru
Joined
Sep 23, 2006
Messages
3,810
One other possible issue that I noticed in another thread is at the bottom of Post #11 by Bronko69er in this thread, http://classicbroncos.com/forums/showthread.php?t=126354&highlight=EFI+spark

Instead of running the run power wire over to the brown wire on the old "I" post, I tapped into circuit "#16" right at the red factory 3 wire connector on this diagram, h t tp://seabiscuit68.tripod.com/images/68-71ignition-color.gif

The pink resistor wire is still in my Bronco. I asked about this exact issue in another thread a few weeks back and VW made it sound like it was OK even with the pink resistor wire in place. I'm not taking a dig with that....just looking for further clarification since someone else before me has had possible issues with this configuration.

VW....Do you still think that tapping the run circuit with the pink resistor wire in place is okay? I don't know if you read the thread link above, but the bottom of post 11 in that thread addresses the same issue. Thanks in advance.
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,316
VW....Do you still think that tapping the run circuit with the pink resistor wire in place is okay? I don't know if you read the thread link above, but the bottom of post 11 in that thread addresses the same issue. Thanks in advance.

It's ok unless your resistor wire is already burned up. It just activates a relay so that's small current.
 
Top