|
Mike,
In the early tuning of my EC2 I had
issues with surging at a number of throttle settings, all low power settings.
Higher power settings didnt show this problem. Problem turned out to be that
adjacent addresses in the EC2 MCT had significantly different values stored. If
you have 2 adjacent addresses where one is significantly leaner (or richer) than
the other then surging is the result.
Think about it. Your throttle setting
arbitrarily ends up on an MCT address that is too rich (as an example). As a
result the engine bogs a little and RPM and MAP drop a little - just enough
to fall into the next lower MCT, which is set closer to a correct value. Engine
RPM and MAP pick up a little and push you back up into the next MCT
location. Again, too rich, engine bogs, etc....
I suspected that this was happening but did
not know for certain because I didnt have anyway to see what was actually loaded
in the MCT. When I bought my EC2 and built my panel Tracy's engine
monitor didnt exist. By the time the EM came out I didnt have any way to
retrofit it into my panel - it wouldnt fit. I ended up buying an EFISM from Ed
Anderson. Once I could see what was loaded it was pretty easy to smooth the MCT
and this cured all of my engine roughness and surging. It also allowed a much
lower idle RPM without any gearbox chatter.
I cant imagine how you could properly tune
the EC2 without having either the auto tune function or some way to display
the MCT. For my installation the EFISM is an invaluable tool. I would say
the same thing about Tracy's monitor but in my case it was much easier to fit
the EFISM after the fact.
I'm sure there could be other things that
could cause the surging, but in my case, this was the problem. I could
have saved myself a lot of hassle had I installed the EFISM
sooner.
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Friday, May 08, 2009 6:44 PM
Subject: [FlyRotary] Initial Tuning at
Low RPM - surging?
I started up the engine tonight, just to be sure it really
worked last Tuesday. Started just fine but there was a
kind of surging of
the engine at the lowest RPM. If I increased RPM it started to smooth out.
Also increasing the mixture
helped a little, but not a lot.
My
question is: is this surging at low RPM indicative of something specific (too
lean/rich mixture, injectors not
putting out too little/much).
Something like that? I am just trying to get a feel for any general rule
when running in that
manner. And if there is no consistency, that's
good to know as well.
Thanks,
--
Mike
================================
Mike Fontenot
Apex
Consulting & Services LLC
Lakewood, Colorado
303 / 731-6645
mikef
AT apexconsultingservices DOT
com
================================
|