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E-MAG Newsletter Oshkosh 2006 View  the PDF

I have received frequent questions asking about my experience with the P-Mag electronic ignition system installation in my LongEZ.   The best way to give a complete picture is to start at the beginning. 

In Dec 2004, while upgrading my plane from a 0235 to a 0320, I was faced with a choice of either buying new Slick mag or trying something radically different, the P-Mag. 

Personally, I never liked mags and I was tired of rebuilding or replacing 1940's technology every 400 or 500 hours.    The EZ has a 150 hp Lycoming 0320 fuel injection engine with a Lightspeed electronic ignition system supplying the top spark plugs, and the P-Mag supplying the bottom spark plugs. 

The Lightspeed Ignition System (LIS) has been trouble free over 2050 hrs, but unfortunately it still requires a constant supply of electricity.  The P-Mag with its own built-in generator gives the best of both worlds, a self powered electronic ignition system.  All spark plugs are Denso resistor type supplied by Lightspeed.  These plugs are exceptional for eliminating electrical spark noise picked up on my Insight Lightning detector. 

When originally deciding to go with the E-MAG Ignitions startup company, I knew from the beginning there would be stumbles along the way.  The E-Mag/P-Mag is a uniquely new product to the aviation market.  The only way for E-MAG to discover weaknesses and improve their product was through in-flight experience gained through innovators like myself.  

As expected, I have had some problems along the way, experiencing two P-Mag failures.  My loyalty to the E-MAG is directly attributable to the excellent customer service and openness of Brad and Tom (the owners of the company).  I can't say enough about the exceptional support I have received.

In my lengthy conversations with Brad I’ve determined that he and Tom have a terrific development plan mapped out from the initial development (two years of development before the initial release on the market) to well beyond FAA certification of their current product.  Development of a six cylinder P-Mag/E-MAG, Continental systems and dual head (single drive) systems are in the works. 

Brad has intentionally kept production and sales volume low during this development period to allow for rapid changes to the design. Personally, I have seen three different case designs and numerous improvements to the board, sensors and connectors. 

The aim of E-MAG is the pursuit of FAA certification in the very near future a process which will take almost two years to complete.  In order to do so E-MAG had to finalize the design of the case, electronics and software.  E-MAG is now confident they are ready to begin the certification process.  With the design finalized, E-MAG can start obtaining bids from suppliers and begin producing the product in greater volume to meet the growing demand.

If my experience with their dedication to the product, innovative ideas and exceptional customer service is any reflection of the future of this company, then I am very confident E-MAG will certainly obtain certification and be a major player in the aircraft marketplace.

P-Mag 1,  Series 112  (serial #138)

The first PMag installed in my plane was #138 installed in May of 2005 with a Lycoming drive gear.  It lasted about 46 hours before I encountered  problems with the engine missing and rough running.   This unit #138 was E-MAG's first generation design.  The problem with the engine missing was traced to the timing index wheel; mounted on the end of the drive shaft it was getting out of alignment thus throwing off the engine timing. 

Note on installation:

I first installed the P-Mag in upper mag hole (#1, #3 cylinder side) with the spark plug wires going from the P-Mag to the lower spark plugs.  


The P-Mag installed in port side of the plane.  Note how close the coils are to the firewall.

For ease of maintenance and removable I relocated the P-Mag to the lower mag hole (#3, #4 cylinder side) and remote mounted the ignition coil.  This position provides additional clearance in a "less busy" area for servicing the P-Mag, and the remote mounting of the coil is a terrific option with the P-Mag.  

   This is the original length of wires routed to the front of the accessory case to the P-Mag.

   I was able to remove about six feet of unnecessary spark plug leads by moving the coil away from the base.  This simplifies installation, wire runs, makes it very easy to service the either part of the P-Mag.   It only requirement is to fabricate a mounting plate for the coils.


The LSI system coils are installed on top of the engine to facilitate short wire runs to the plugs.

P-Mag 2, Series 113 (serial #234)

At the time of replacement, E-Mag was in their second generation design.   The replacement P-Mag (#234) was of a slightly different electrical design which incorporated numerous improvements such as an improved dynamo for low speed operation, improved bearings, and other electrical improvements to prevent the index timing wheel miss alignment issues I had in #138.  The timing magnet is now placed soldered into an aluminum cup and adhesive bonded to the shaft. 

This time I used a supplied E-MAG drive gear instead of my Lycoming gear to check for reported wear problems which was reported by other builders.  

The installation was a bit frustrating only because it used a different tach pulse signal and different style installation connector.  After a little bit of trouble shooting with the generous help of Jack Wilhelmson (electrical engineer extraordinary) everything was working fine again.

Note: while using #234, I had a complete failure of the ignition electrical system on a long cross county flight due to a bad common ground supplying both the Lightspeed and P-Mag systems. The Lightspeed system was completely off line, and the P-Mag was supplying all the engine's ignition and running on its own internal generator, just like a regular mag is supposed to do. 

Surprisingly, I didn't notice any difference in engine operation or smoothness until after landing (the engine quit due to low rpm).  The P-Mag functioned as intended and most assuredly had saved me from a most unpleasant situation (being a lawn dart)..

After 84 hours of flawless operation, P-Mag #234 failed on the way to Oshkosh July 2006.  Cruising at 10k ft, I first noticed my tach signal had failed (it is supplied by the P-Mag) and after doing a mag check I discovered the P-Mag was gone.  I immediately made the decision to do a precautionary landing at Lexington, KY. 

I had noticed a few anomalies the day before I left (you know… plane owner’s intuition) and thought that  I might be developing a problem with the P-Mag.   I had made contact with fellow builder Harley Dixon prior to heading out, since E-MAG was at OSH and out of touch at the time.  Harley had an unused first generation (#119) P-Mag ready to ship out to me... just in case.   A quick call, and it was on its way to me (THANKS Harley).

After receiving the overnighted P-Mag #119 the next day, I installed the unit in about 30 minutes, did my ground testing, and off I went to OSH, only to have it to start running rough about 20 miles out from Lexington.  

The story of my quick return to Lexington FBO includes a fire truck and police escort with emergency lights on while taxiing in.  I had not declared an emergency, but the officer told me "It's just standard procedure" to which I responded, "you guys must be really bored around here".

I did some more tinkering, decided to abandon my Oshkosh hopes, and fly back to Charleston.  Ten miles out I was again rewarded with a rough running engine, a quick return to Lexington, and another fire truck and police escort with blue lights while taxiing into the FBO.  I was asked if I was the same "LongEZ feller" who flew in earlier.  I sheepishly said "Yes I am". 

More tinkering on both ignition systems and this time I flew a race track over the airport for 20 minutes to check out my work, everything seemed good, so it was off to Charleston, SC and home.

After my return home, I contacted Brad of E-Mag at Oshkosh, who immediately overnighted a new system of the latest design.   I told him of my experience with my temporary replacement P-Mag to which he responded, "You should have NEVER have flown with that old P-Mag, because it had known reliability issues." Apparently there were only 16 or so of the "original" first generation ignitions shipped and Harley and I just happened to have had them (can you say early innovators)..  E-MAG voluntarily replaced all of them a while back and Harley (who had been waiting until his bird was ready for flight to upgrade his units (much to my misfortune) is now in the queue for his new replacements.

I did check the E-MAG supplied gear after 84 hrs of operation.  There was no noticeable wear, just some burnishing which is similar to my Lycoming gear.  This "no wear" conclusion was also verified by my oil filter magnet and routine inspection of my oil filter paper element (I cut the can open each oil change).


P-Mag 3, Series 113, (serial #613)

The new design had quite a few improvements from the previous generations such as:

  1. Ventilated case for better cooling.

  2. E-MAG now utilizes a magnetic sensor for determining crank angle position (eliminating the index wheel).  This prevents the timing issues I had with my first two units.

  3. Different type of connector which makes installation and removal much easier.

  4. An epoxy coated circuit board.

  5. Since the circuit card is installed into the base with only one wire connector, field rebuilding/replacement of E-Mag/P-Mag computer takes only a few minutes

  6. E-MAG has settled on this design configuration as the “final design”. With the design finalized they can work on increasing production, improving E-MAG code, and adding features to the “E-MAG Interactive Control and Display” (EICAD) interface software.

    P-Mag with the coil removed with the new connector setup

    The generator part of the system with just one plug to the computer.  A magnet is mounted on the shaft with interacts with a sensor mounted on the bottom of the board.

    The board is now sealed with an epoxy coating.

Another innovation I like about the new design is the “Quick-Set” timing method.   

  1. You install the P-Mag/E-Mag in the accessory case hole in any orientation with the timing gear in any position and lock it down. 

  2. Rotate the prop until you have the top dead center mark aligned with the centerline of the case (some engines use a mark on the starter to set TDC). 

  3. Turn on the power with the mag switch in the off position. 

  4. Attach a piece of tubing to the MAP port and puff into the tube. The system will arm (LED will start flashing red), then you puff a second time into the tube and the LED will turn solid green (timing is set).

This makes installation and timing a breeze and much easier than the mag rotation method, although the traditional method is still available if you wish to use it.

Again, as with the two previous designs, there is a different set of connectors and my tach didn't work after installation.  A quick call to the company and I was able to hook up my lap-top computer to the P-Mag and using their EICAD software, reset the P-Mag voltage and tach pulse output to 12v and everything is working great.  A future release of the EICAD software will let you set the timing by just plugging into the P-Mag/E-MAG systems, set your engine at TDC and click the timing set button in the software menu.  If you intend to use the E-MAG system, I would definitely recommend wiring in a permanent connector (3 wires to a serial plug) to allow interfacing with a laptop.  It will make setup a breeze.

For my own curiosity, I also installed a remote temperature sensor pressed onto the P-Mag case to measure my in-flight temps.  I have found it generally averages around 130 F. 

E-Mag recommends keeping the ignition temp 190 degrees max (the same spec for magnetos).   E-Mag has seen units coming through the shop with recorded high temps of 235+ degrees.  Since the max temp is recorded to memory at the time of shut down, it means the unit was functioning properly at the time the reading was taken.  Such readings are examples of successful high temp field operation, but they are very cautious about overstating that end of the envelope, and want to avoid people thinking 200+ is OK. 

To this end, installed a "blast tube" on my P-Mag (as recommended in the manual) at the same time I installed the temp probe, but really haven't seen very high temps at my P-Mag even though it is on the "hot side" of my downdraft cooling system.  I did measure 145 f on startup after a 15 shutdown, but shortly after taking off, the measured temps fell to my normal range (125-135f).


Apparently, the highest temps seen by E-MAG's occur when you shut the engine down after a flight and not while the plane is IN flight.  The latest model has a built-in hour meter and temperature sensor which records current and maximum temperature seen at any time while in operation (accessible through the EICAD software).  It will be interesting to check these metrics out on my bird after a few months of operation.

Running with  #613, I have noticed slightly smoother operation, and a definite improvement in the smoothness of self powered P-Mag low RPM operation.      

I have an Insight Lightning detector on my plane which is VERY sensitive to any electrical noise pulse in the plane (switches, plugs, strobes, etc).  I have discovered the coils (both P-Mag and Lightspeed) put out a considerable amount of continuous lightning-like noise which is undetectable in most planes, except those with a lightning detector installed while the engine in operation.   

After years of troubleshooting, Chrissi (Cozy girls) provides the final suggestions to solve the puzzle (tin foil of all things).  After discovering the source of my noise, I first tried putting AL foil tape around the coil, it was so successful, I decided to make it permanent.


I finally ended building a “faraday" type cage around the P-Mag coil which has completely eliminated all the coil noise.   Here I am covering the coil with copper screening

I covering the coils with fiberglass BID, a grounded cage of CU metal foil screen another layer of BID, then used the Lo-Vac method bind it all together.


The P-Mag system is now completely “silent” to the Lightning detector at any RPM. 

I am in the process of building a similar faraday cage around the Lightspeed coils to "quiet" them too.

Parting Thoughts

I think E-MAG’s latest generation ignition system shows great promise.  The component configuration has reached maturity, E-MAG intends to “lock the design down”, start planning for larger purchasing of components (instead of mainly in-house production), and begin pursuit of FAA certification.

The only true test of the long term vitality of the units is time.  Each generation of E-MAG has shown incremental upgrades to the design, features and reliability.  I still believe E-MAG is on the right track and is well on the way to eventually replacing the Slick style mag.   I remember changing points and condensers in my 1963 VW and how much better our cars are with electronic ignitions.  I don't want to go back to a mag unless I have a compelling reason to do so.  I am not at that point...

I for one, will continue to stick with E-MAG because of their terrific customer service, and I am confident their dogged determination and tenacity will make this product a success.