Timing vs CHTs with PMAGs

[Randy]

I recently had several Alarms on my dual Pmag setup using the EI Commander. I talked to Brad at Pmag about the problem and also Bill at EI Commander. As a result of those conversations I chose to take the situation seriously.

I pulled both Pmags and verified I had the hardened gears with official part numbers on them. The gears were in great shape.

As I was putting it all back together and setting the timing again, I believe I found the cause of the alarms. One of the vacuum lines going to one of the Pmags had a tiny slit in it. Just enough to leak sometimes. The slit happened right at the end of the little metal tube it connected to so pushing on it too hard with my arm when working in there could have caused it.

Since repairing it I have made to cross country flights of about 5 hours duration each with no alarms, and the divergence between them usually sits at 2 degrees.

In this case, the cause of the alarms did not cause any real danger, as one mag was simply not getting the signal to advance timing as much as the other one. It was a rather difficult item to trouble shoot and even after calling the experts, the cause was not on the "suspect list". That is why I write this here. If you get timing divergence alarms, check the vac lines, a mush easier task than checking the condition of the gears etc.

[N941WR]

Great news Randy!

Thanks for the update.

What was odd about your leak was that it only impacted one P-mag, not both. Had it impacted both, you would have seen it on the EIC by no advance being displayed. Due to your small split, it was probably opening and closing with the power pulses.

[FasGlas]

I would like to add to that:
I was just in the Capitol Airshow at Mather AFB, CA. While I was there I had many pilots come by to talk shop and inevitably the conversation would get to pmags. I lost count on how many pilots told me about pmags failing, either one or both at the same time. The beautiful RV-8 parked next to me and his sons RV next to him both had full pmag failures in flight. I didn't ask what the planes were from the other pilots.

Last week I flew to KDVT, AZ to buy a Glasair III. While there I again talked with pilots and again pmags reared it's ugly head in the conversations and again failure after failure.

Along with the failure stories there were the high CHT's complaints. The low bearing TBO's, timing shifts and general lack of any confidence in pmags. So for anyone not feeling confident with their pmags you're certainly not alone by a long shot. I have never been happy with them, and thank the powers that be, I have not had a full failure in flight. yet!

I'm sorry if this post ruffles the feathers of the pmag proponents but this has been such a common story that it's fact, not rumor. I have posted reams of data about pmags and it all proved everything a (large) hangar full of pilots have been telling me for years.

PS.. I would really like to thank Ed and Bill, without them the EIC would not be available. Without the EIC I would have had a very hard time diagnosing the pmag problems and recording the data.

[N941WR]

Yes there have been P-mag failures but the question I always ask is, "When did you buy them and have you had them in for the version 40 upgrade?"

We have found that the majority of issues people experience today is a direct result of the installation. Which is a result of people no reading the manual and/or not understanding ignition timing.

For example, wiring them to the same circuit breaker, clamping down the vacuum line, not installing a restrictor in the MAP line, or not installing the jumper on a 20 or 25 degree engine, and more.

The issue Randy had was with his install and had nothing to do with the P-mags. In fact, the P-mags operated perfectly.

[FasGlas]

[Please read the rules regarding civility.

I deleted your text in this post.

v/r,
dr]

[N941WR]

I was not referencing you or anyone in particular. I was simply pointing out that most of the issues I have helped people work through had to do with the installation and that the current production product is reliable.

I was not pointing a finger at you or anyone in particular.

[FasGlas]

Originally Posted by N941WR

I was not referencing you or anyone in particular. I was simply pointing out that most of the issues I have helped people work through had to do with the installation and that the current production product is reliable.

I was not pointing a finger at you or anyone in particular.

"The issue Randy had was with his install and had nothing to do with the P-mags. In fact, the P-mags operated perfectly."

And where was this finger pointing to? You know I personally replaced three pmag boards, shipped them both back to emag and got them back still not working. You have all my data that proves everything I have been stating for years. You saw all the timing shifts and large diversions, and lets not forget the complete timing into space flight I had to figure out and fix myself.. Yeah, you know.

Uncivilized text deleted by dr. ]

[N941WR]

Go read the first post on this page, the one posted by Randy.

[FasGlas]

Again, please read the rules regarding civility here. I can assure everyone I will win those arguments <G>. Text deleted, dr (site owner)

[skylor]

Originally Posted by FasGlas

"The issue Randy had was with his install and had nothing to do with the P-mags. In fact, the P-mags operated perfectly."

And where was this finger pointing to? You know I personally replaced three pmag boards, shipped them both back to emag and got them back still not working. You have all my data that proves everything I have been stating for years. You saw all the timing shifts and large diversions, and lets not forget the complete timing into space flight I had to figure out and fix myself.. Yeah, you know.

You do realize that Bill was addressing Randy Crothers' issue in the underlined segment above, and not you, "FasGlas" right? I suspect your real name is Randy hence the reason you think he's referring to you?