From: Mike Fontenot <mikef@apexconsultingservices.com>
Subject: [FlyRotary] Re: Initial Tuning - Today
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Monday, May 11, 2009, 11:35 PM

Tracy,

>>All good except for (again) the MAP increasing.   My guess is that you Assumed that the MAP went up when the RPM went up.   This does not happen under these circumstances without increasing the throttle.  See previous comments on this.  Think of the engine as a vacuum pump (it is).  If you do something to make the engine (vacuum pump) turn faster WITHOUT opening the throttle more, the MAP is going to go DOWN (more vacuum), not UP, as the engine sucks more air through the same restriction.<<

Right, yes I probably did assume that when the RPM went up so did the MAP. Good explanation, I'll be sure to observe that next engine run. Its not Cold Fusion (power de novo).

>>Are you saying that the MI jumps around (up and down?) all the time, when you move the mixture control, random direction  when you move the mix control, or what?   Position of O2 sensor (too close to end of pipe, too cold a position, etc), exhaust leaks, engine miss, bad connections, poor ground, and other things can cause bad indications. <<

When I was in Mode 3, and adjusting the mixture knob, the direction of change of the Mixture Knob and the increase and decrease of the Mixture Indicator were in the same direction. It was just that what I thought was a small change on the Knob resulted in a big change on the Mixture Indicator. Same when using the Program KNob and Store button. One push to increase injector flow rate there could make the Mixture Indicator go from position 3 of 16 to 11 of 16.   Movement of the Mixture Indicator always tracked the Mixture Knob or changes via the  Program Knob, but I was expecting smooth increases. And in Mode 3 that generally did not happy, they were larger changes. I hate to use this term but 'twitchy'.  Again, I will run it up again and watch, note these specific things. 

I might try checking the wiring and putting a ground strap on the O2 sensor as a first attempt.

--
Mike

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Mike Fontenot
Apex Consulting & Services LLC
Lakewood, Colorado
303 / 731-6645
mikef AT apexconsultingservices DOT com
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