I have found in my installation that around 15-16" Hg

manifold and

approx 2800-3000 rpm that I need to program the system in much

finer

increments of Manifold pressure and rpm than elsewhere.  If

I do not,

everything is fine at idle and everything is fine higher

than 3000 rpm but

as I increase from 2000 up through 3000 the air/fuel

indicator will shift

from rich to an lean indication and the engine will stumble

a moment.

Interestingly enough I don't notice it in the air.

Ed Anderson

Thanks, Ed I will try that. It is hard to get it to stay at a steady

MP

around 16" because it appears to lean out as it drops below the

staging

point, then MP increases and secondaries kick in again. It surges at

about a

one second cycle. I can stop the surging by manually richening the

mixture.

I don't notice it in the air either, except sometimes when throttled

back on

short final. Mostly does it on the ground when taxiing by onlookers

:-)

Chuck Dunlap

I encounter the same conditions.  But, I find if I sort of ignore the MP
reading and advance the rpm in stages of 100-200rpm increments between

about

2500-3000 and reset the processors MAP by using mode 1 so that the

manual

mixture control set at 1200 gives me a rich indication on the air/fuel

meter

that takes care of the stumble.

Ed Anderson

Tracy needs to put a bit of hysterisis(s?) in the software.
Either that or gradually transition from two injectors to four.

It is easy to get theses kinds of control problems when using computers
in real time closed loop systems. There are delays in certain sensors.
Perhaps the MAP, perhaps the intake manifold temp (highly likely) perhaps
even the RPM (somewhat likely).

Try moving the throttle very very slowly.

Paul Lamar

Another thing to try is to set the MAP table write width to minimum (in mode
2) before doing the mode 1 programming.

Some EC2 users avoid the transition stumble by moving the transition point
to a different manifold pressure (in Mode 7).  Unfortunately, Chuck has an
early EC1 controller which has a fixed manifold pressure for stagging.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

 
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