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Sunday I took the trike out for more tuning with a buddy who is very
engine experienced. He wanted to get a baseline so we checked a few
things including compression on all 4 cylinders. All good and
consistent. Examined the sparkplugs and they showed good and clean. We
also hooked a Vacuum gauge to the throttle body and checked steady
pressure. It was. I should note that the EM2 MAP display and the vacuum
gauge did not match up. Lastly, we adjusted the throttle stop and idle
adjustment getting the low end idle to around 1000 RPMs. We never got
the engine running smoothly at this idle, but it did run. And it would
stay running. It really smooths out at 1600 RPM.
-- MODE 3 - With TC latest advice about not really using the
Mixture Indicator, but instead find out where the engine runs
'strongest' at any particular MAP setting, we started tuning again in
Mode 3. After getting the system to MAP 22, we found the Mode 3 setting
where running with the Mixture Knob at 1200 produced the best running
engine. Turning the Mixture Knob either Lean or Rich would cause the
engine to eventually drop in power and smoothness.
To help measure 'strongest' we set an RPM point, then watched it either increase or decrease based on our programming settings.
Mode 3 Injector value: 203
At MAP 22 the engine RPM was 5120, EGT around 1200, Oil Pres: 63, Oil Temp: 150, H2O Temp: 193
-- MODE 2 - It took us a couple of readings to figure out where to
go, but we did get the system responding to the Mixture Knob in a
consistent way. At a high idle I can now clearly affect the engine with
the Mixture Knob, after changing the Mode 2 settings. As I said
earlier, at the lowest idle of around 1000 RPM the engine runs rough.
It almost looks like the engine fires slowly, throws the big prop over.
The prop sort of slows down, then the next cylinder fires. Not sure if
this is making much sense but the engine chugs along at low RPM (1000
to around 1500), above this it smooths right out and sounds like a
sewing machine.
Interestingly, the low RPM MAP values were down around 7.4 . They
hovered around 8.x until I got over the RPM of 2000, then climbed
after that. I am doing all of this at 5500' above MSL, not sure if that
makes a difference.
-- MODE 1 - Putting the system into Track Mode I made some
adjustments in Mode 1. We ran out of time to go in 1/2 MAP increments.
So instead I picked about a value of 3 increments: 15, 18, 21, 23, 26,
29. The one tricky part was that in Track Mode, above some MAP/RPM
value the EM2 did not show RPM, but instead it showed another value ( calculated MAP maybe?).
I'm not sure where the cut over occurred, but I used another technique:
I have a handheld optical RPM meter, and using that when set on any
specific MAP position, I then used the reading on the RPM meter to see
if the engine is running 'stronger' or 'weaker'. Plus listening,
watching temps, things like that.
At the end of the day I could start the engine with Mixture Knob in
1200, let the engine warm up, and run through the entire range of
throttle settings up to max throttle without touching the Mixture
Knob. I call this progress. There are still a few places that 'bump'
every now and then. I'm sure that would cause a poop event if happening
to me while flying. So of course I plan to go back and fine tune the Mode 1/Mode
9 the next time out.
But overall we feel like a lot of progress was made. At every throttle position I can spin the Mixture Knob away from 1200 and it clearly affects the engine (it produces 'less'), and when bringing it back to 1200 it smooths out and runs strong again.
-- MIXTURE INDICATOR QUESTION - My understanding is that the EM2 is a Narrow Band type of meter, when coupled with the O2 sensor I have (BOSCH). Have others found it useful to have a Wideband Air/Fuel gauge and O2 sensor installed in the system to understand where air/fuel really is? Or is there some technique folks to calibrate the EM2 Mixture Indicator so that it reads accurately? As you know by now, it is certainly possible I am mis-interpreting the values I am seeing on the EM2 Mixture Indicator, but I'm feeling less confident with the EM2 Mixture Indicator. That value seems like such a damn useful reading to know. I'd rather have no meter than an inaccurate one! Anyway, feedback is appreciated.
Thats it for now, Thanks,
--
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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