Lou,
If the engine is surging, it's too lean.   When it does it, try turning the
mixture control to rich, as a test.  It should stop the surging when you
make it richer.  You'll probably find that you have to turn the mixture knob
to at least the 3 o'clock position or more to stop the surge.

At lower RPM's the mixture has to be pretty rich to run smooth.  You'll
probably have to tune the idle by how it runs and sounds rather than the O2
sensor.

Steve Brooks


-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On
Behalf Of lou rubin
Sent: Sunday, January 14, 2007 2:11 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] engine surging at low manifold pressure

We have recently tuned the Ec2 on a 20B & although it
has helped it run a little smoother we still get alot
of roughness & surging at idle from 15 to 18 inches
Mp& especially when pulling back power Has anyone
experienced this problem? The plane has been run on
the ground, however the problem was just as bad in air
in a descent.

Lou & Paul  N ES 117ES




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