Tracy,
I have always wondered why so many people
seem to have trouble with staging, myself included. My setup uses all
four injectors of the same part number and the flow rates and dynamic ranges
are very well matched as demonstrated on a flow bench.
As you know, I am in the process of
retuning my system after an EC2 upgrade. When looking at data logged from
the EC2 at less than 1 second intervals, there appears to be an inconsistency
in the manifold pressure corresponding to the staging address and the manifold
pressure the EC2 reports when staging actually takes place. In my case
staging will take place with the manifold pressure reported by the EC2 up to 4
In Hg less than that corresponding to the staging address. So far I have
not seen the system stage at the manifold pressure corresponding to the staging
address.
Is it possible that the EC2 is actually staging
at a lower manifold pressure than that set in the staging address, using the mixture
correction table value at that lower address, and when the manifold pressure
rises sufficiently, the correct correction table addresses are used again? With
my mixture correction table, a significant increase in table values is required
just above the staging threshold. If the above were happening, the
mixture would go very lean when the EC2 staged and used the values in the
correction table lower than the staging address. This is what I see on
the O2 sensors when there is a problem staging.
I hadn’t tried to change mode 6
settings since I am sure my injectors are very well matched and the manual
indicates that in this case mode 6 changes shouldn’t be needed. Your
message brings up the thought that if the above is happening, one may be able
to use mode 6 to obtain a mixture correction table where there is no or very
little change in table values for addresses in the region corresponding to the
staging point and a couple of inches of manifold pressure below that.
Then it wouldn’t matter exactly what manifold pressure the EC2 actually
staged at or the actual correction table value used since the mixture would still
be close to correct. Mode 1 or 9 may still be able to obtain correct
mixtures outside this region. Is it possible that those who have no
staging issues have stumbled on this type of mixture correction table
accidentally?
Crawling back into my hole to continue to
RTFM.
Steve Boese
-----Original Message-----
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Tracy Crook
Sent: Tuesday, February 17, 2009
9:30 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Second
flight
Again,
it is very important to understand what is happening. Without this
understanding, a builder is working in the dark.
Fuel delivery is not doubled when the EC2/3 goes from staged (2
injectors) to unstaged (4 injectors). The controller cuts the pulse
length to about 1/2 when this happens so the net effect on fuel delivery is
very small. The amount that does change should be tuned out by using Mode
6 PRIOR to any MAP table tuning. See the previous message on this
subject.
When in doubt, RTFM! One caveat. The manual has been updated many times
over the years. If you don't have a current edition, feel free to ask for
a MS Word copy of the manual via email but be sure your controller has been
updated to match the documentation.
Tracy