92 Ranger cranks, no spark. 3.0L Auto tran

My ranger has had a quit and leave me on the side of the road problem since I bought it a few years ago but it always starts up after it cools down later and haven't been able to properly trouble shoot it. Couple weeks ago it quit and wouldn't start again...yippeee. It stayed broke so now I can fix it. I found a stripped gear on the distributor...3 brand new distributors later (they wouldn't sit down all the way on the block because the hole in the end of the distributor wasn't deep enough for the oil pump drive rod) I finally bought a remanufactured one that dropped right in and figured it would run....nope. The distributor was problem #2.

Problem #1 is I had spark at one point while swapping distributors but now I don't. I have a signal at the ICM from the distributor pick up coil. It pulses 4.8V while cranking. I replaced ICM and had old one tested later and it checked good. Ignition coil has voltage through it but never pulses to induce spark. Replaced coil anyway still no spark. Replaced EEC module no change. I'm dumbfounded. Been checking grounds and wires for good connections found nothing yet. Any ideas? Ordered a code scanner and a temp sensor. not in yet

This doesn't look good...25 lookers and no takers with ideas?

1992 Ranger with 3.0l will have a TFI system
Good read here: http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

Download and print the worksheet.

The stalling when warm is a classic symptom of a failing TFI module, many have remote mounted these for just that problem.

Brief how it works:
A coil works by generating an electric charge then collapsing the field that holds it, when a coil gets 12volts, + and Ground, on the Primary an electrical charge builds up in the Secondary but it is a static charge, in order to discharge this higher voltage you must collapse the Primary field, you do this by cutting the Primary's power, this is done by cutting the Ground to the coil, when Ground is cut Secondary discharges and spark plug sparks.
Older "points systems" had the Ground for the coil running thru the points, a cam on the distributor shaft opened and closed the points cutting the Ground to the coil, generating a spark at the right time in the right cylinder.
Good system but.............points wore out and always needed adjusting.

TFI system removed the points, a sensor in the distributor detects the cam lobes and this tells a "transistor" to cut Ground on the coil, so same basic system but without that part that wore out.
Way better but not bullet proof because electronics do wear out especially in hot conditions, and in high demand uses.

The TFI module runs the show, it passes on timing pulses to the computer but doesn't need the computer to generate spark(cut the ground), computer helps in spark advance timing.

You can test a coil simply by powering it and then removing the ground, it will generate a spark each time, give it 12v on + terminal then touch Ground wire to -
Pull if off and spark will happen, do it as fast as you want, only takes milliseconds to generate a field.

Your no spark, assuming the distributor is turning, is either the sensor failing to tell TFI module when lobes are passing by or TFI module failing to respond to these "pulses"
Wiring, of course, is 23 years old and can get frayed.

A Coil will not last as long if it is given the full 13.5-14volts(alternator voltage) when engine is running, but you want a "hot" spark when starting a cold engine, this is why you see separate "start" and "run" circuits on systems that use distributors and 1 coil.
But this can lead to a common problem on these systems.
The "Start" circuit can fail, so there is no 12v at the coil when cranking, but there is when key is in RUN position, so you test the coil for 12v and it is there, then crank the engine but No Spark???
That's because when you turn the key to START, voltage at coil is cut off, so always good to test coil voltage when cranking engine, just to be sure.

TFI was replaced and old one was tested good. No spark with either one installed. This truck is cherry. Wiring all looks and what I have tested good. No corrosion anywhere. I have a signal from the distributor at the TFI. I'm going to test and replace the Ignition coil again. be back soon

If you have a tachometer watch it while cranking engine, it gets its pulse from Coil's Ground, if it isn't showing RPMs when cranking could be Ground isn't being lifted.
Also you can use a test light, hook it to the Coils Ground wire and battery's positive, light should pulse on and off when cranking.

There are at least 2 different TFI modules that are not interchangeable, I think they used different distributor sensor, but can't remember.

Ok...I have done the test with the coil before and it worked...now it wont work with the old or the new coil...I don't get it. Coil is mounted key on with red/lt green wire removed from plug and inserted on primary spade term. jumper on neg of primary and scratched on the engine. the jumper wire sparks as it should but no output on coil. ??? Any ideas?

This does not have a tach. Test light does pulse when hooked up as you describe. All wiring hooked normal to coil. test light from pos on batt to neg on coil. It does pulse.

scanner just showed up I can do some testing with that now.

Did you print the work sheet: http://www.therangerstation.com/tech_library/images/tfi_worksheet.jpg

It may seem silly but it really works to eliminate possible problems in the TFI system if you go step by step.

Have you tested that coil is sparking manually, use a spark plug wire with spark plug on one end and plug the other end directly into the coil, by-passing rotor and cap.
Then connect and disconnect "-" terminal on coil with key on(12v at the coil's + terminal), you should see a nice blue spark at the spark plug
yellow spark means weak spark, which often can't start cold engine

yes, I went through the test sheet a few days ago. I did test the coil manually or what I call bench test it. using a spark tester directly off the coil no cap n rotor involved. no spark there but two different coils ohm out ok and do not fire. I don't get it. I have tested this coil this way before and it checked out but not now with either coil but still ohm out ok. The scanner is telling me the switch for the transmission is in gear but that seems like if it were true it would not crank??? It will crank. This problem is really making me feel stupid. I have a degree in Electronics Engineering and have worked on vehicles and small engines my whole life. Im 48 and not feeling so smart with this :-(

Ok...not funny...It has spark now. Don't know what caused it to work

swapped in the old coil again...no spark. swapped in new coil. It works again. more news later after I button everything up

NSS(neutral safety switch) feeds both the starter relay and the TFI module power when Key is in START position.

Coil is usually powered(+ terminal) by the EEC Relay

Starter relay("S" terminal)--------/-NSS-------Ignition switch(START position)---12volts
TFI Module-----------------------/


It is not uncommon for people to by-pass the NSS switch, but often they only do the starter relay not realizing the TFI is on the same wire.
The NSS just screws in to trans above shift linkage, it is a plunger type switch so is adjustable to a point.
Common issue on Ford trucks with column shifter is that the cable end under the dash gets loose so doesn't pull shift linkage all the way so NSS doesn't go all the way so in Park it won't start but it will in Neutral, Reverse lights are on the same switch so if they go off with a wiggle of the shifter then either NSS needs adjusting or cable does.


OHM test on a coil will for sure show if it is bad, but can not show if it is good, lol, one of those old ball things I am sure you have run into in electrical design.

Here's what I know so far. I have spark now. The TFI module was the wrong one. Only works with my old unit installed. Also had the Ignition coil fail while I was working on the distributor issues. Just had the wrong combination of incorrect TFI and bad coil installed at the same time. Good call on having the wrong TFI

Next probem...it won't start or fire. Timing light shows spark is retarded about 100 degrees with the spout disconnected. the marks on the balancer are pointing roughly at the power steering pump when the #1 plug fires. I figured i put the dist in a couple teeth off so I pulled the #1 plug (front plug, passenger side), installed a compression tester and rolled it over till the needle started to move indicating compression stroke, then I finished rolling it up to TDC by hand and pulled the cap off the dist...rotor is pointing directly at the #1 tower on the cap and the cast lobe on the dist casting. It looks good to me. How could electronic timing be so far off from TDC?

With SPOUT disconnected the computer is not in control of spark advance.
Common setting for base spark timing is 12degrees BTDC

Distributor turns at 1/2 the speed of the crank, so if crank turns 360degrees distributor has turned 180degrees, so 120degree of crank rotation = 60deg of distributor rotation

The 6 spark plug wires on cap are 60degs apart

If spark is happening 100deg BTDC, or ATDC, then that would be 50deg of distributor rotation.
I would guess the spark plug wires are in the wrong place on the cap.
It is too close to being 1 place off

And just so I am not confused, Advanced spark means a higher Before TDC number, Retarded spark is higher After TDC number.
So 20deg BTDC is more advanced than 10deg BTDC