I went to the airport again. I sat in my car for a while reading the instruction manual that came with my MicroTech ECU.  I decided to look closer at something Rusty thought might be a possibility….there is a hard and a soft cut for max rpm’s.  That could be what was limiting me to 4800 rpm’s, even with the smaller prop (with less pitch) that I just installed. No such luck….the rpm limit feature was turned off on the computer’s screen. 

     There are four ways to adjust the mixture on the MicroTech (so far, that I have found….possibly there are more ways). One way is to use the “mix trim” which will adjust the mixture settings throughout the whole range of rpm’s, from idle to WOT.  Then, there is a way to adjust it via throttle position sensor settings. There is also an idle mixture screen, a cruise mixture screen, and a WOT mixture screen.  I had very good results yesterday with the idle mixture setup screen…you just select the idle MAP and use the plus and minus buttons to adjust the mixture on various maps, such as 10” Hg,  15” Hg, 20” Hg, etc.  I did that and got excellent results of a smooth idle and transition.  So, I decided to go into the WOT screen. First, I wrote down the default values,  then while advancing the throttle to wide open, the engine stabilized at 4800 rpm’s.  I then scrolled to the 5000 rpm screen, and used the plus/minus buttons to start increasing mixture ratios.  Plus 10 % did nothing. 20, 30% seemed to have no effect. When I hit around 42 %, rpm’s started increasing….5000 rpm’s, 5100 rpm’s…  When I advanced it to 48%, I was up to 5300 rpm’s static. Hooray !!!  (the mixture values can be adjusted from -98% to +98%).  The water temps were approaching 200 degrees by then, so I shut her down and pointed the fan to blow up the NACA and cool off the engine/radiator, etc.  Definitely a success.   Engine/water temps were high, and the sun was low, so I pushed it back into the hangar to await another day to fly it.

     I just got off the phone with Dave Atkins (from whom I purchased the MicroTech, the TWM throttlebody and intake manifold, and he told me that I would see further improvements by simply connecting BOTH hoses to the throttlebody to measure manifold vacuum. I presently have only one connected, and the other one has just a short hose and a bolt stuck into the hose to block it off. He said I would get less map fluctuation by using both connections.

     I’m fairly confident I will have a favorable “next flight report” to share with the improved power. I had previously tried enrichening the mixture with the “mix trim” that would enrichen all settings, but when 10 or 15 % made no difference, I quit trying, as the idle mixture was getting so rich it would barely run.  Now that the idle mixture has been leaned slightly, and the WOT mixture has been enrichened a whole bunch, it’s like having a new engine. Power….Arrgggh !!!  Thanks to all who offered suggestions. Gotta get into the MicroTech manual some more….gotta find out what else it can do, like cook breakfast or ?  Take care, and thanks again to all who helped with prop selection, mixture setting suggestions, etc. etc.     Paul, got the power, Conner