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PMAG issue/fix

AX-O

Well Known Member
Today i wanted to go flying. So i did the preflight, had my test plan ready and pushed the plane out. During the preflight i moved the exhaust pipes and the right pair felt a little different. Humm, that is a little weird.

I started the plane and all appered to be working well. When i did the mag checks i knew something was wrong immediately. After troubleshooting i noticed that the number 3 cylinder egt was dropping as soon as i killed the good mag. Pretty easy to see with the engine monitor.

So i taxied back and started to remove the cowl. As soon as the cowl was off, the problem was easily spotted, one of the PMAG wires (#3, imagine that) came off the back of the PMAG. I put the wire back in but the standard click when correctly set on the PMAG did not happen. I found an unused new wire and gave it a try. Click!! So i checked some of the other wires and 3 more were extremely easy to remove. No click. I took some needle nose pliers and crimped the metal portion of the wire. Now they all click and feel secure.

I am not sure what happen. The plane now has 15 hours on it. I know that when i made the wires, they clicked nicely when installed. I will keep an eye on them.

As i was checking around before putting the cowl back on, i found a broken adel clamp. The one that held the right exhaust pair to the engine mount. Well that makes sense.

Got everything back together and went flying. Had a great flight. Has anyone had a similar issue with the wire coming off the back of the PMAG? My guess is mine came off during last flight because the previous mag check passed on the ground.
 
I have no experience with Pmags, but quite a bit with auto ignition. Usually the only terminals that click on the coil side are the GM HEI style. Inside the rubber boot is a steel band in the shape of a C. It has a spring tension and ball socket arrangement to hold it on the terminal. It "clicks" as it goes over the fat part of the male post. If your connectors have lost their temper after 15 hours (or at all for that matter), they are of poor quality and should be replaced. While squeezing them worked initially, they have proven that they will not hold their shape.

Consider yourself lucky that only one failed and you caught it on the ground. I would replace them without delay. This is not a normal failure for HEI style connectors. You don't want critical parts that require this type maintenance. No place to pull over in the sky with your pliers :)

Larry
 
In 700 hours I have never had a plug wire come off the P-mags or sparkplugs.

Is it possible that your connector wasn't pushed all the way in until it "clicked"?

BTW, The RICommander can tell you if a wire has come off, or if you have a bad plug, or ...
 
I also run dual Pmags on an IO320. And yes I have had this happen.
My cure is to use a dab of dielectric grease followed by a zip tie about the rubber boot.
Keeps out moisture out as well as keeps the boot tight.
 
Is it possible that your connector wasn't pushed all the way in until it "clicked"?

BTW, The RICommander can tell you if a wire has come off, or if you have a bad plug, or ...

Bill, I made sure they all clicked and were set correctly. Your commander is a future upgrade. Just not there yet. Don't have the time or money right now.

I also run dual Pmags on an IO320. And yes I have had this happen.
My cure is to use a dab of dielectric grease followed by a zip tie about the rubber boot.
Keeps out moisture out as well as keeps the boot tight.

Good idea. Thanks.
 
Larry, where would you buy yours? I got mine with the PMAGSs.

I would order a set of high quality auto ignition wires, like Accel. I got their 5000 series for my EI set up. They have SS connectors instead of brass. Less than $50 on Amazon. They are custom though and you will need to crimp them yourself.

Larry
 
The coil side of the Pmag is not a standard terminal end. Similar in concept, but about half the contact area as a spark plug/GM HEI terminal. I dont know what it is used on the in the automotive world, but Axel, I do have a few laying around of you get stuck.

I think the actual wire that Brad uses is of reasonable quality, but that too is available in bulk from a myriad of sources (I bought mine from Summit when I installed the CPi system, along with terminals and boots - all in bulk).
 
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True confessions

. Has anyone had a similar issue with the wire coming off the back of the PMAG? My guess is mine came off during last flight because the previous mag check passed on the ground.

Axel,
Had this happen not once but several times ( I am a slow learner). Finally it took a telephone tutorial from Brad to solve the problem. You have to take a pair pliers and squeeze the connectors ever so slightly so that they make a good connection. It was so simple and obvious and I cannot explain why the devil it didn't occur to me when I installed the doggone things. Haven't had a bit of trouble after that.
 
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