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Hi Steve, I always find something interesting in your reports, in this one I'm most interested in how you know what the Mode 3 and Mode 6 correction values are. Are they displayed by an EM2/3 or do you have something custom of your own making?
If you start with ALL DEFAULTS then adjust Injector Flow rate with Mode 3, followed by Mode 6 and maybe Mode 2 your Mixture Correction Table would be a flat line at either 0 if display is -128 to +128 or it would be 128 if display is 0 to 256. Which in my opinion tells you nothing about fuel delivery - the only way to know what your fuel delivery is in this scenario would be to display the injector pulse width from BIN 1-128 or read your fuel flow meter.
Jeff
From: "Steven W. Boese" <SBoese@uwyo.edu>
Subject: RE: [FlyRotary] Re: Engine Tuning
Date: Thu, 19 May 2011 00:58:26 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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
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