At cold idle you would want a much richer mixture than a
warm idle. I cannot see the changes if any, even though I have
a big screen. Street cars bias pulse width with data from the
coolant temperature sensor.
Timing at cold start could be 20 degrees and once you have
a start could go to 22 degrees.
22 degrees is plenty until you are close to cruise power.
Then as you lean to cruise mixture, the timing can go up a
bit to account for the leaner (slower burning) mixture.
For closed throttle above idle RPM descents you can go up
to 40 degrees of advance.
Idle fuel flow but at high RPM you need extra time to burn
the idle mixture (the Renesis goes to 44 degrees), to keep the
heat in the rotors and prevent unburnt fuel from entering the
exhaust and muffler, lest the fuel ignite with surprising
power and a big flame ball. Very impressive in a race car but
too spectacular for aviation use.
I would not put much faith in a F/A gage during throttle or
RPM transitions. At any RPM point if the pulse width and fuel
pressure didn't change then the mixture didn't change.
You will or may detect RPM/mixture combinations that report
unhappy tuning when you pass through various combinations of
tuned length/back pressure/timing settings. You can have cold
air entering the muffler and flowing quite a distance through
it in some cases. Not so much in Renesis engines with no
overlap. Same thing around the oxygen sensor, where gasses
that have passed over the sensor come back over it in the
opposite direction.
So EGT probes and oxygen sensors are mounted on the outside
of curves where possible.
Never a problem in long exhaust systems. Airplanes tend to
have very short exhaust systems.
For full power tuning go too rich first. It is hard to hurt
or stop a rotary from too rich a mix.
Peak EGT is not good for apex seals. So stay rich of peak
or well lean of peak EGT.
If you tune too lean the engine will shut off just like the
ignition was cut. Just like your engine dying at idle. Just go
richer and base it on coolant temperature.
Just a guess though.
Lynn E. Hanover
Last
night I turn the sound recorder on the laptop on while I
did a
tuning run. I played back the data in MegaLogViewer while
recording the
screen, and then matched it up to the sound. I was hoping
I could get
suggestions for improving the tune.
The first issue is the hard start. The only time I
purposefully turned
the engine off was at the very end. It runs pretty
smooth, once it is
warmed up to about 120*F, but below that the AFR will go
off one end of
the scale or the other, indicating that fuel isn't getting
burned.
http://www.youtube.com/watch?v=F3pYW1lOcTo&feature=youtu.be
The top graph has RPM, manifold pressure and throttle
position.
The second graph is injector pulse width time, AFR, and
fuel flow.
Spark advance is on the third, along with mapDot and
tpsDot. Those are
measures of how quickly the map and throttle position are
changing. The
computer uses them to calculate how much to extra
pulswidth to add on
acceleration.
The bottom graph show the oil temp, coolant temp and
manifold air temp.
Instantaneous values for each line show up at the center
bottom of each
graph.
The last line at the bottom is a run time timer.
The bouncy balls to the right are the tables that the
computer uses to
calculate the injector pulse width and spark advance.
Lowering the
numbers in the VE table tells the computer that the engine
isn't sucking
as much air as theoretically possible, and the computer
will lower the
amount of fuel at that combination of RPM and manifold
pressure. If the
ball is between cells, it uses a weighted average of the
adjacent ones.
It just pulls the number from the spark advance table and
sends it to my
EDIS modules.