First ost here. Read hours of threads, learned a lot.
Started with crank, no start.
Many hours later finally swapped 1 yr old MSD 8227 coil with new one fired right up.
KOEO tfi coil- reads 5.8 vdc. Is this correct.
My other truck '90 5.8l reads 11 vdc approx.

Do I have a TFI problem?
I also have new error code eec-iv 19 = internal voltage wrong.

I will replace capacitors

Any one have this coil- voltage that's correct level

Thanks
Oh, wires and cap rotor 1 year also , truck stored for 8 months

 

The coil should have full battery voltage on the positive side whenever the key is in the Run/Start position.

For reference:

courtesy of oldfuelinjection.com

 

RLA2005
Thanks for the reply.
I didn't explain well enough.

I have found a lot of diagrams and measured different areas.

The initial problem was had fuel , had spark per test light.
Spark plugs looked good when out and grded.

Coil was firing but not hi enough voltage , found out when timing lite didn't work.
works on my 1990 f250 5.8l
Coil was bad. replaced starts and runs fine.

I still measured all voltages when running or key on engine off.

Found signal coil- from tfi to coil - i/p not coil + (battery side)
Coil- that fires the coil was at 5.8vdc approximately on my 1990
f250 it is approx. 11.6vdc.

Do I have a problem with tfi or something else like 22k noise suppression resistor that is also part of that circuit.
Don't want to replace parts without having some input from people more knowledgeable then me.

Curretly looking at replacing capacitors in EEC-IV 8PZ

Thanks to any comments


Si

 

I think I understand your question now. If you are getting only ~50% of the supply voltage measuring on the Coil (-) terminal then I would suspect a problem with the TFI module. With nothing triggering the TFI it should essentially be an open circuit. Your example leads me to believe the TFI is in some undefined state or perhaps a shorted transistor internally.

My buddy Joel5.0 has some great into on troubleshooting the Ford TFI ignition here: SBFTech.com TFI Module/Hall Sensor Testing Procedure

I suspect a simple resistance check on the TFI pins with a DVM may prove or disprove my theory.

BTW that 22k ohm resistor is not for noise suppression, it is a current limiting circuit to send the ignition signal to the computer (PCM). The resistor provides the buffered IDM signal.