Could you provide more details,
Chris. RPM where surging occurs, manifold pressure, staging point, etc.
Most of the time if you have a surge it is
caused by the engine encountering a leaner region at higher rpm. This
causes the engine to die back until it hits a richer region, where it again
picks up power and increases rpm into the lean regions, repeat ad infinitum.
Here are some possible causes (assuming
the A controller is really OK):
1.
The A controller may simply have its MCT set too lean at some higher rpm.
When you enter the surge region, try enriching your mixture by turning your
manual mixture knob to the right. IF this improves or increase the rpm at
which the surge occurs then I would suspect a MCT table needs enriching.
2.
If the A controller had a restriction in its manifold connection/line then it
may not see the increase in manifold pressure (and thereby enrich the fuel
mixture) soon enough to make the adjustment and the engine runs lean.
3.
One set of your injectors (most likely the secondary) are not turning ON as
they should. However, with most engines with near equal size injectors in
primary and secondary, the engine should run up to 6000 + rpm on just one pair.
- Its
possible you have some sort of fuel restriction but the fact that it runs
OK on the B controller would seem to indicate that is not the problem in
this case.
Here’s a couple of other things you
might try
1. Try setting your “A” controller’s MCT back to the
Default settings and see if that helps (check your manual on how to do this)
2. Make sure the temperature probe for Controller A is not accidentally
getting grounded. The A controller will run without the temp probe
connected, but not certain what problem it may see if it is grounded.
Best to check to make certain.
Let us know how it goes
Ed
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Chris and Terria
Sent: Saturday, October 17, 2009
10:49 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] EC-2 A and B
differences
I
am still trying to get the engine to run smooth. It has been surging on
me. With fuel pressure steady, the mixture and the RPM jump around a lot
(I haven’t started taking exact readings yet, still trying to
reduce/eliminate surging).
Today
I tried swapping around the vacuum lines, and as an afterthought, I selected
the B controller, and the engine smoother out, and RPM jumped up considerably.
So
I am wondering what the difference is between the two. What are the extra
things that A looks at that B doesn’t? This will help me figure out
a troubleshooting procedure. Maybe I can isolate the faulty component.
I
looked through the EC-2 manual and couldn’t find anything listed.
Maybe I missed it.
Chris
__________ Information from ESET NOD32 Antivirus, version of virus signature
database 3267 (20080714) __________
The message was checked by ESET NOD32 Antivirus.
http://www.eset.com