Source: 2018 Q2 Beartracks, Ed Meyer – Bearhawk Patrol N101EP (Co-owned with Paul Nowaske)
As promised on the Bearhawk Forum after a few requests, here is a write-up of our experience with the Electronic Fuel Injection and Ignition (EFII) system.
Why EFII
As a bit of background, I had a couple years of experience beginning 1969 where I worked in an FAA repair station overhauling Lycoming and Continental engines. My job was to overhaul accessories which included carburetors and magnetos. During this time I gained good understanding how they work and always thought that a carburetor in particular was a pretty crude way to get fuel into an engine. The one plus is that it is very simple. Later, in the ‘80s, automobiles transitioned almost exclusively to using electronic fuel injection and ignition and I observed that the reliability of our cars went up significantly without the frequent attention that the temperamental old systems required. We wanted something more modern for a new airplane.
The EFII system seemed to fill the bill. We opted for the dual system with many redundant components for reliability. We have two of most of the components in the system so that no single component failure will stop the engine. There are two crank position sensors, two MAP sensors, etc. driving two different ECUs. The ignition is driven by both systems much like dual mags where one set of plugs is fired by each. The injection is controlled by one system with a switch to change to the other if needed. This is always checked during run-up assure both are working properly.
Other considerations
The EFII system is 100% dependent on a steady supply of electricity for operation. Therefore we chose to install redundant electrical systems. We have the normal belt driven alternator plus a gear driven alternator on the vacuum pump pad. These each have an Earth-x battery. There is a main bus and an E-bus that each feed the redundant components of the EFII system. One of the optional components in the EFII system is a box called a Bus Manager that helps to insure power is always available. Given our dual electrical systems, the Bus Manager might not have been necessary but one feature included in it is automatic fuel pump switching if the main fails. I once had an engine failure in a low wing airplane which requires fuel pumping. After getting on the ground, luckily safely, and thinking about the events, I could not remember if the aux fuel pump had been turned on immediately. It was on after landing but I don’t know when it got turned on. Lots to think about when it got real quiet up front like where to land and such. The automatic switching appealed to me. This is checked at every engine start. When the system is first powered up, there is no fuel pressure so the Bus Manager switches to pump 2 automatically. Once the pressure comes up the selector switch can be set to number 2 then back to number 1, the main pump, it will stay on number one unless fuel pressure drops.
Installation
The EFII system has a good set of instructions for installation and we had little difficulty with following them. It required pulling the intake tubes from the engine and sending them in to have fittings welded on for the electronic injectors. (I understand the new System 32 EFII does not require this.) Also, the flywheel had to be sent to have a permanent magnet installed for the crankshaft position sensors to detect.
The EFII requires a fuel return line to be installed. We puzzled over this quite a bit to try and make this as simple as possible. Installation of a header tank was considered but rejected for a number of reasons. We finally decided to simply add a fuel fitting bung to each tank at about the center of the wing root rib lightening holes for easy access. A friend was a good aluminum TIG welder and did a first rate job on them. We opted for the duplex SPRL V4-4P fuel valve that includes left, right, both, and off settings for both the feed and return. Not knowing how much fuel returns, it seemed good to return it to the tank is comes from. I still do not know how much returns but I have since seen where some airplanes have return lines going to only one tank regardless of which is selected. This would be somewhat simpler than what we did but I would still want to know that the return volume is relatively small before I would opt for this.

We did have an issue installing the fuel valve. We had the lines all nicely run and hooked up and then during pressure testing it seemed the valve was not sealing as it should resulting in phone calls, emails, returning valve, etc. Turns out that we had installed it wrong! Somehow we had assumed the top section of the valve was the feed side and the bottom was the return. Not correct. After re-plumbing it was fine.
Our fuel system uses Bob’s design through the gascolator. Lines come from fore and aft of each tank to tee fittings inside the boot cowl then through the fuel selector valve to the gascolator. The EFII instructions state that a gascolator is “not required nor desired.” We chose to use it anyway for a couple reasons. It gives us a low point to sample the fuel for contaminants and it provides a screen ahead of the inline fuel filters that are supplied with the EFII system. One critique of inline fuel filters I have heard is that there is no way to tell if they are becoming plugged up. I think with the gascolator, if there were enough contaminants to be a problem they would show up there first.
After the gascolator, the fuel flows through the first inline filter then to the redundant fuel pumps which are under the floorboard near to the fuel valve. The pumps come mounted parallel in a manifold that has a single inlet and outlet. From there the fuel flows past the firewall to another large fine inline filter before going to the ‘rail’ which is hoses running to each injector in series. The picture below shows the secondary filter and fuel lines in-side fire sleeve running to #3 and #1 cylinders as well as the lower spark plug wires. From there a hose connects to the fuel pressure regulator which is mounted on the firewall. Then it returns to the fuel valve and finally back to the tank.

The ignition portion of the EFII installation is quite simple. The two coil packs need to be mounted and there were magneto cover plates provided that had mounting provisions for the coil packs. Crankshaft position sensors need to be installed near the flywheel on the front of the engine and the plug wires had to be made up to length but all the parts were provided. One of the advantages of the system is that it uses automotive spark plugs which are much less expensive than aviation plugs. Knowing we were going to use this system, we had Bob install cylinders set up for 14mm spark plugs when he built our engine. Even with the unshielded wires and plugs there is very little ignition noise in the radio. If I have the radio squelch open I can detect a small amount of noise that changes with the ignition checks during run-up.
Oxygen Sensor
One component that is separate from the EFII system but recommended is the installation of an O2 sensor and gauge for reading fuel/air mixture. In automobiles running unleaded fuel, the O2 sensor feeds back to the ECU so it can automatically adjust mixture for optimum. The EFII system does not use this feedback in order to maximize reliability since O2 sensors often fail, especially with leaded fuel. The sensor is mounted high in the exhaust only 3 or 4 inches from the cylinder head which is claimed to help it keep from fouling. So far so good on ours and I have heard of them going several hundred hours without problem. The mixture gauge, which gives a real time F/A ratio reading, is real nice to have especially when doing the initial setup of the system. In the picture at the right, the F/A mixture gauge is in the center above the EFII programmer with the mixture knob is to the right of it. The switch on the right is to select which ECU is controlling the injection with the 88 ECU normal. The key switch is left of the programmer.
Operation
The EFII system comes with a ‘programmer’ that provides the interface to adjust settings in the system. We opted to install the programmer in the instrument panel but it is not actually required during system operation. I have never changed any settings in flight and do not intend to. I have looked at some parameters occasionally but it is not easy to see in flight.
Before first engine runs, Robert Paisley, the man behind EFII, sent a set of values to update the default settings that were in the system. Robert spent 30 or 40 minutes on the phone with me describing what all the parameters are for and what settings I should change and what to be very careful of changing.
On first attempts at starting, it was somewhat slow to start. The system ECUs are identified and 71 and 88, which is a reference to the rotational reference of the crankshaft trigger sensors that drive them. It finally started by changing from 88, which is considered to main ECU, to 71 and adjusting the mixture knob richer. I later found that the selector switch was installed upside down, (amateur built you know) so it actually was on 88 when it started.

We ran it several times at various power settings looking at the mixture and adjusting until it was about right. This was done by setting the mixture knob until the mixture reading was about 12 to 1 then reading the percentage of knob adjustment on the programmer followed by changing mixture setting values for the various RPMs by an equivalent percentage and trying again to zero it in. This sounds like a lot of ground run time but it actually was not much.
I toyed with the idea of having someone with more recent experience than me make the first flight and there were volunteers willing. I opted to fly it myself mostly because of the EFII system being quite different and by now I un-derstood it better than anyone in the area. While flying I would carefully monitor mixture, adjust the mixture knob and then change settings back on the ground until it dialed in pretty well.
On early flights, the CHTs were a little high so we had to work on that. I think the biggest part of the fix was in-creasing the air outlet size at the bottom of the cowl and installing a lip. We also adjusted the baffles a little espe-cially right in front of #2 cylinder to allow more air to flow past the area that has very little cooling fins. One other change which seemed to help some was to change the timing a little at high power settings. This is also done from the programmer interface. I did not even open the cowling for this. It has settings that increase the timing up to 30 degrees before TDC above about 1500 RPMs. Additional settings retard it back a few degrees at high MAP. I in-creased these setting for a little more retard at high power. Especially for a new engine I would recommend that more retard is good at high power.
Normal Operations: Start-up begins with turn on of the fuel valve (the pump howls loudly if turned on before the fuel valve) followed by turning on the key (equivalent to master switch) which powers up the system. As previously mentioned fuel pump #2 comes on requiring the pump selector switch to be set to #2 then back to #1 which veri-fies the automatic switching function and verifies both pumps are operational. Once the EFIS boots up, I crack the throttle a bit and activate the starter switch. The starter can draw current from either battery or both and all this functionality came prewired with the Bus Manager. As it stands right now, when the engine is cold, I normally have to run the starter for a few seconds, pause a bit, and then activate the starter again and it fires right up. (I under-stand it is possible to update the firmware in order to be able to open the throttle a time or two the get the equiva-lent of an accelerator pump function providing a bit of prime.) If the engine has been run, even after several hours, it starts right away on the first try hot or cold. There are zero hot start issues.
Run-up includes an ignition check where power to each coil pack is turned off momentarily to ascertain that they are fully functional. There is no ‘mag’ drop when doing this. If anything there is a very slight increase in RPM. I suspect this might have something to do with flame propagation in the cylinders and the 1700 run-up RPMs. Also, momentarily switching from ECU 88 to ECU 71 during run-up verifies that ECU 71 system components all work properly. To shut down after flying: turn off the key. Just like a car. I normally turn off the fuel valve as well but having forgotten that a time or two created no issues other than some fuel migrating from one side to the other via the both setting of the fuel valve.
LOP Operation: With the EFII system it is easy to run well lean of peak. I am able to run it at about 16-17 to 1 and it still runs smooth. I can detect a slight power drop with it this lean but it stays smooth and CHTs drop about 20 degrees. According to Dynon, this is nearly 100 degrees LOP. I have thought about changing the settings for fuel flow to automatically lean like this at the RPMs I use for cruise which are generally anywhere from 2200 to 2400. I have been reluctant to do that because I am afraid that while increasing RPMs like starting takeoff, or going around, it might cause a stumble when going through these cruise RPMs. The benefit of this would be that the mix-ture knob could simply stay centered for all operations. Instead, for now at least, it is set to be equivalent to full rich when the knob is centered and when in cruise I can turn the knob to about the 10 o’clock position for LOP. This works easy and predictable. A good thing is that once set, it stays even when changing altitudes. A before landing checklist item is to reset the mixture knob back to center much like setting the mixture to rich for legacy systems.
Would I Recommend EFII? Yes. The engine runs very strong and smooth. I have no way of knowing how much power it is actually making but it feels strong and others have commented on the performance of the airplane. There is definitely a learning curve with the system. There is little doubt that it was somewhat more expensive than an old fashioned carburetor and magneto setup, especially with the addition of the second alternator and battery. Is it worth it? It was for us. I like it.
Robert Paisley adds: “Since Ed’s EFII installation, there has been a major update in the design of the EFII systems.
EFII is in the process of releasing all-new control electronics with many added features designed specifically for the needs of experimental aircraft. The updated EFII kit is called System32 – additional information can be found at www.flyefii.com.”