What's new
Van's Air Force

The definitive Van's Aircraft support community! Buying, building or flying an RV? Join our exclusive family of mentors and enthusiasts!

P-Mag One Dead Plug Wire Terminal

Karetaker

Karetaker

Well Known Member
Howdy everyone. I have remade new plug wires and checked the system using the "Pull Thru" test in the P-Mag manual. It appears I have a single dead spark plug wire terminal on one mag. I have swapped good wires/plugs from other terminals that have spark and they do not spark on this one terminal. (The 3-4 bank on the P-Mag.)

Speaking of banks; the manual states that the terminals within a bank are interchangeable. That seems to me that they are electrically connected somehow inside the mag. So, I am confused as to how one terminal wont fire, but its mate is fine.

Both mags were sent out for service/software updates a few years back; I do not recall the exact timeframe. But the mags only have about 16 hours on them now. If it matters, these mags are from 2012 and have the gold bodies.

Anyhoo...any suggestions on what I might be able to do/check prior to sending this thing out for service? (again)

Much obliged.
 
Pmags of this era use COTS Ford coils. You could probably have Amazon ship you a coil today and swap it out for less than the shipping cost back to Hartzel.
 
Toobuilder said:
Pmags of this era use COTS Ford coils. You could probably have Amazon ship you a coil today and swap it out for less than the shipping cost back to Hartzel.
Click to expand...
Got a part number? Googling "COTS Ford coil" doesn't yield any definitive results for me. As an aside, has anyone here done an autopsy of an EMAG with pics for our edification?
 
Interesting...I'll look into it.

I am interested in disassembly of a P-Mag to lean more about them. (just not mine...yet...)
 
Found this:

Post #8

PMAG coil

Does anyone know if the PMAG coil an off the shelf item or specifically made for/by EMAG Air? My understanding has been that it is a Ford EDIS coil but I can not find a part number or even a picture of it that is from Ford. Thanks in advance
vansairforce.net

Doing some fast searching on Amazon, it appears part number FD497 is the same item for the coil 26C1081.
 
Karetaker said:
Interesting...I'll look into it.

I am interested in disassembly of a P-Mag to lean more about them. (just not mine...yet...)
Click to expand...
Just put your spare on, and then you'll have time to play with the one that's failing. (You do have a spare, right? RIGHT? :D )

Take care removing the screw from the coil pack - they seem to be on very tight and the screws are glued on with locktite - I almost stripped one trying to get it off to put on the adel clamp.
 
Your problem doesn't sound like the coil. Not famaliar with EDIS stuff, but in general, wasted spark coils fail in pairs. It is closed loop between the two plugs on one coil. Energy flows out one terminal to plug, jumps gap and goes to block then to next plug, jumps the gap, then back to the other coil terminal. Break that circuit and neither plug fires. I thought EDIS was traditional wasted spark, maybe someone else here can confirm that. Wasted spark coils are not grounded, so spark energy does not return to the coil via ground, like traditional coils.

EDIT: This may be a generalization and very possible that the EDIS coils are configured differently to allow one plug to fire in a pair. It is possible to have 4 coils in there using a grd return path even though they fire them in a paired wasted spark manner. I could see ford doing that to limit problems from a single plug failure.
 
Last edited:
Thanks Larry. What you describe above is what I am curious to know specifically with P-Mag and how they operate. I will be removing and bringing home my P-Mags today to see what might be going on.
 
Karetaker said:
Howdy everyone. I have remade new plug wires and checked the system using the "Pull Thru" test in the P-Mag manual. It appears I have a single dead spark plug wire terminal on one mag. I have swapped good wires/plugs from other terminals that have spark and they do not spark on this one terminal. (The 3-4 bank on the P-Mag.)

Speaking of banks; the manual states that the terminals within a bank are interchangeable. That seems to me that they are electrically connected somehow inside the mag. So, I am confused as to how one terminal wont fire, but its mate is fine.

Both mags were sent out for service/software updates a few years back; I do not recall the exact timeframe. But the mags only have about 16 hours on them now. If it matters, these mags are from 2012 and have the gold bodies.

Anyhoo...any suggestions on what I might be able to do/check prior to sending this thing out for service? (again)

Much obliged.
Click to expand...
Just experienced an NGK plug failure. You certain they're all good?

I had a series of multiple PMag failure/repair/failure cycles back in the 2015-17 time period. They've performed well the last 6-8 years. I believe several things changed for the better at Emag in that timeframe. (Might consider proactive overhauls with close attention to actual replacement of suspect parts).
 
Last edited:
I think I remember, in some thread back some months, that there was a guy that did have a wasted spark coil (Lightspeed unit I think) fail on one output. I was taken aback I recall as I didn't think they could fail that way.

Of course it may be my memory that's failed, not the coil.
 
You must log in or register to reply here.
Back
Top