Paul,

Refering to the P-Port thread, I was reading the Mazda paper you recently
posted on the Le-Mans 4 rotor and it seems they had the same problem,
which they corrected by putting the fuel injectors as close to the engine
ports as possible. fwiw  Perhaps you could take another look at that
paper,particulary the last three or four paragrafs.

Thanks :

Grant D. Taylor.

 I think Mazda did that for throttle response reasons. A race driver needs
power
right now. Mazda probably used a throttle position sensor, RPM and maybe
the
intake manifold pressure as well to calculate the fuel needed. Tracy's
system
does not use a TPS but the Megasquirt does.

I think we have another problem and that is the intake pressure at
a particular time, in the intake manifold, is changing with RPM. I suspect
Tracy is briefly measuring the pressure, in the intake manifold, when
another
chamber face is 22 degrees BTDC. IMHO we need to either average the
pressure
somehow or use a mass airflow sensor that averages the amount of air going
in
the engine.

-----------------------------------------------------

BTW Mark's P-port engine runs smoothly from idle to 5200 RPM (near max
power
at 5200 RPM) and the mixture is a constant 12:1 with the EFI manifold
pressure
sensor  DISCONNECTED <<. The injectors are located up near the air
funnel.
He could fly it now with nothing more than a leaning knob for setting
the mixture at cruise. Such simple systems work well with aircraft engines
as the fixed pitch prop load is predictable.

This is good evidence that a simple 555 system will work well.
The mass airflow sensor will be icing on the cake with the 555 system.

Paul Lamar

That is incorrect.  The engine was running smoothly with the Manifold
Pressure  connected <<,  2200-5200 rpm.  That was only one run, however,
so until it is repeatable I am not saying that it is all OK.

It is too early to comment on the mixture, since the O2 sensor was not
getting good data likely due to the exhaust design & the placement of the O2
sensor.  It was definitely not behaving correctly with respect to manual
adjusting of the mixture.

We're redoing the exhaust to quiet the engine down & repositioning the O2
sensor so there is no possibility of contamination by outside air / ensuring
it gets hot enough & stays hot enough.

So, we're down for  the count until we get new welding done.  Hopefully only
a week or two.  And then we can start again.

Mark (Rocky Mtn High)



Somehow I was under the impression from private email that the manifold
was disconnected. You told me you made a run with the manifold
pressure disconnected. You also told me the mixture was 12:1.
Here is what you wrote.


======================================================================
"Mixture?  It was 12:00 the entire time after start.  No change from the
EC2's default computed value.  No clue what that value might be.
If you meant MP, I'm afraid I did not note it down at the time."

"mrs"


Paul Lamar wrote:
 Disconnect the manifold tubes.
 Set all the table settings up a couple of number from what they are now
 and try it again. Keeping doing that until it runs well at max static RPM."

 The computer will think the throttle is wide open all the
 time. So the top numbers are probably the most important.
 You can try doing it to just the top table numbers first.
 Those should be all the computer is looking at because
 it thinks the throttle is wide open.

 I forgot to mention. Put the mixture control knob
 in the full rich position when you do this as the engine
 will be two rich at half throttle setting and below and you
 will then have to lean it manually. Report back  :)

 Paul Lamar

"I already know this will work - what is the point of doing it?  When I last
ran the engine sans-manifold pressure tubes, the engine ran great within a
band from 1500 - 4800 or so.  This was the range where the mixture could be
brought to 'perfect' with just the mixture setting."

"The EC2 ships with all MAP cells defaulted to 0.  To get the higher RPM
range going, one typically adds to the default; for the lower ranges one
subtracts (each cell can have a signed int +127 to -127.)  So - it was no
surprise it worked in the mid range with no adjustment."

"Anyway - doing the experiment is not a problem, I'm just wondering what new
will be learned by doing it."

"Mark"

=========================================================

You are now telling me the mixture monitor was not working
and it was not smooth with the manifold pressure disconnected????

When you get the mixture monitor working do the run again. Disconnect
the pressure hoses, set the mixture knob to half way and do the run
in 1000 RPM steps. This will reveal the base mixture settings with
out being screwed up by the manifold pressure.

Tell me what the mixture is at each step when you get the
mixture montor working. I don't know what brand you are
using but there are several wide band mixture monitors
out there sold in the thousands. They can be at the end
of the exhaust pipe and they still work. They do not have
to be heated by exhaust gas as there is a heater built in.

We will never get this working until we isolate the problem.
Tracy is not going to tell us when and how he is measuring
the manifold pressure. I have cc'ed him every step of the way
and so far have not received a response.

Paul Lamar