Brian and Ed,
In order to compare the resulting mixture based on mixture correction table values, the other EC2 parameters from mode 3, mode 6, and the mixture control setting as well as the injector size and fuel pressure must be comparable. As both of you have indicated, the result of all of those variables as well as others can be seen in the O2 sensor reading. That reading is fast to respond and easy to interpret.
With conditions of RPM up to 6800 and MAP of over 29 inches, it is possible that the fuel requirement exceeds that of the 28 and 40 lb injectors. This is where knowing the EC2 parameters might be useful. I’ve attached a snapshot of data collected today from my EC2 with the following parameters:
Mode 3: 175 (67-255 range)
Mode 6: 127 (0-255 range)
Mixture control: 256 (full rich -256 to 256 range)
Mixture correction table: 127 (-127 to 127 range)
MAP: 29.5 inches
The green trace is the injector signal where the injector is delivering fuel when the voltage is pulled low. The white trace is the CAS signal from which the RPM can be determined. The data is from the instant that the transition from pulsed to static injector operation is taking place.
Under these conditions, the injectors go static (not pulsed but open full time) at 4000 RPM. At RPM greater than 4000, the mixture will go lean since the injectors are already delivering all the fuel they can.
Keeping the parameters the same as above except for setting the mixture control to zero (mid range), the injectors go static at 5600 RPM.
The modes 3 and 6 parameters are just my guesses at what might be reasonable for the injectors in use. If Brian can retrieve the actual Mode 3 and 6 values from his EC2, I can test those parameters in my EC2 here and see if his injectors are really be going static. It is not necessary to actually have the injectors to do this. This would be useful information because if the fuel flow is limited by the injectors, making changes to the mixture correction table or the mixture control would be ineffective at resolving a lean condition at high RPM. This may help in determining if mixture is the problem or if it might be timing.
Steve Boese
RV6A 1986 13B NA RD1A EC2
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of bktrub@aol.com
Sent: Tuesday, May 17, 2011 6:42 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Engine Tuning
Thinking on it a bit, I realized that what would probably happen at WOT when flying as opposed to a ground run, is that my mp is going to decrease from 29.1 to a somewhat lower value, since the RPMs will increase up to ~6800 or so, up from the 5200 at static WOT. So, I would be running at a lower MAP address than the 106 that I see at WOT static. So, should I not richen the MAP values BELOW 106, and a few adresses above it since I should see a little gain in mp due to the ram effect of my air scoop?