Hi Steve,
Just about any device that uses MAP sensors can be/ may be seriously
effected by the powerful wave forms in the intake manifold.
We have found this on the EC2 as well as the Pmag electronic ignitions
(which also uses a MAP sensor). One reason it does not happen all
the time is that the complexity of the wave forms and where they interact
(add/subtract) with each other as well as you manifold sensing port location,
manifold shape, rpm (and undoubtedly even more factors) and it can either
result in no problem at all – or a major problem.
Since rpm has a significant influence on the creation of finite amplitude
waves, its not surprising that you may have no problem at one rpm and a
significant one at a different rpm.
You problem may not be the result of MAP influence – but, since it is
rather easy to stick a restrictor (or a small plastic fuel filter) in the line
and then see if that has any effect on the problem, I would try that first,
before tearing into anything. If it does not show any impact, then you
have not spent a lot of time or money.
Just my $0.02 worth.
Ed
Sent: Friday, July 29, 2016 7:50 AM
Subject: [FlyRotary] Re: Further testing
Hi
Steve
Just my 2 cents, I had irregular map signals so I installed a mig welding
tip for .6 wire and that sorted it out simply for me.
Cheers
Christian
On Friday, 29 July 2016, steve Izett <
flyrotary@lancaironline.net>
wrote:
Hi
Guys
We did further testing of the Renesis today. Would really
appreciate your heads on this.
Last series of tests we had this major
missing and noise which I think is fuel exploding in the exhaust.
This
happens at various RPM’s based on load from the adjustable prop.
With fine
pitch it would spin out to just over 7000rpm before striking this
mayhem.
With medium pitch it would get to 6000rpm before the same
symptoms.
From memory these were both at about 22-23 inches of Hg.
My
Wideband O2 is malfunctioning at present.
The narrowband response time
appears to slow to discover what the mixture is doing during the
episodes.
Also still having trouble with the EM3. Sometimes display
reads what appears to be an error message and at other times stops reading
RPM.
The Skyview Engine monitor has the same issue at the same RPM so
appears directly related.
I changed the input on the Skyview to the
Standard RPM input as I incorrectly fed the injector pulse to the lower
voltage input, but this made no difference.
I had wondered if the
secondary injectors weren’t getting power and as a consequence when it staged
to all 4 injectors the trouble began.
Using the EM3 display (staging
asterisk) and switching power off to the secondaries I was able to ascertain
that the secondaries appear to be functioning fine.
I did notice that the
point of staging appears to be not solid.
This takes me back to Ed’s
comments re damping the manifold signal to the EC2.
Sorry Ed, you might
have had it right last week. I thought because it was running so smoothly up
to 23 inches that it wasn’t a signal issue.
Maybe the wavelength/timing of
those pulses at ~6000rpm matches the manifold signal tap position!
Ed,
you mentioned either small orifice or accumulator. I estimate the volume of
the signal line to be approx 18 cubic centimetres.
My gut was that the
accumulator required to damp the signal would need to be an order of magnitude
larger. (total guess)
So maybe 180 cc’s but thats half a Coke can! Seem’s
way to big.
Ed, did I understand you right that a small fuel filter can do
the trick? I thought they would only be about 10 cc’s in volume.
I suppose
if the pulses are very narrow/short maybe thats all to takes to damp out the
pulses.
Can I ask the group please. Who had trouble with manifold
signal and what was the solution that worked best.
Paul Lamar advocates
tapping the signal from the oil injection ports. Has/is anyone using this
solution?
Thanks very much everyone.
Steve Izett
Glasair
Super II RG
Reneis 4 port EC2 EM3
RD1-C
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