Paul,
Bill Bradbury described what's happening with his engine, and it sounds
pretty much the same as what's going on with mine. Below staging, it's
smooth, but above, it runs rich and in flight there's a lot of popping
and surging.

He then reports that he has had good results by swithcing his stock red
and blue injectors to the yellow ones, that  I 'm assuming, but I'll
check are yellow  RX-8 injectors. Will they fit my 93 13 BREW and where
can I get them for as little $ as possible, and how much would that be?

On another note, I still have not gotten the last few pages of the plans
for my RV off to you, I still have to get up to the hangar and get them
off to you.

Brian Trubee


I have not researched the supply yet but Michael Hart is about to do
that so
he will let us know.

Sounds to me like the trim map is wrong on the top end. You could have
one or more partially clogged injectors. It takes a special circuit
and a burette to test injectors. The fuel coming out should be
directly proportional to the pulse width.

Here is a schematic of a DIY test device.

Also you could sample the air pressure in the runner with a couple
of pressure sensors and a data acq system. If my plate was not running
over I could come up and do that. It will be the end of April before
I am free enough to do that.

I don't think the RX8 injectors  will fit your current injector holders.
You could get RX8 injectors and they might not change things. If not
it is the trim map. If they do you may currently have one or more bad
injector. Getting them tested may be the first thing to do.
There are some companies around that specialize in cleaning and
calibrating. Paul Yaw may still do it. http://www.yawpower.com/ New
ones are getting so
cheap it might not be worth it.

Where are Bill's injectors mounted?

I see your secondary injectors are on the outer tubes a foot or so
from the port. What happens when you lean them out?

Is that a damper I see on the end of the secondary fuel rail?

Take some closer pictures of the EFI system.

Don't worry about the plans. Michael White kindly made me a gift of
a set he was not using. Thank you Michael. They came in.

Paul Lamar

I had the injectors cleaned and flow tested just prior to engine start.
 The thing you see on the end of the secondary rail is the fuel
pressure
 regulator.

 The other day I went out and ran the engine up on the ground,
 specifically looking at EGTs for a mis-match of EGTs above the staging
 point. What I saw was that the EGTs were pretty consistent all the way
 up and down the RPM range. So, I'm thinking that I'm just rich up
in the
 areas above staging. Well, the EC2 should be able to compensate if I
 tune it right, so I'll keep twiddling the program knob. When it runs
 smoothly, it's like silk. I"m just a bit tired of the tower getting
 calls from the local communities about a plane in distress overflying
 them. Also developing a crease in the bottom seat cushion from
excessive
 pinching.

 Brian Trubee

Is that a stock fuel pressure regulator? 2nd gen or 3rd gen?
1993 is a bit ambiguous. The 3rd gen pressure regulator must have
a manifold pressure connection because it was a turbo.
Do you have a fuel pressure gage on the instrument panel?
Do your injectors look like any of these?

Generally speaking it is better to up the fuel pressure a few psi
and reduce the pulse width as you are more likly to get a nice fine
fuel spray. No dribbling :)

The best info I have on that regulator is 37 psi but it goes up and
down 1:1 with the manifold pressure.

Paul Lamar



I'm running between 37 and 40 PSi on the fuel pressure.There is a line
from the pressure regulator that I have connected to the MP pressure
line ( actually, it tees into the line coming from my pressure taps.

I'm just waiting for the next clear day so I can tie the plane down and
run it up for some tuning.

Brian Trubee

You might try going up on the pressure and down on the pulse width.
I would swap out the stock pressure regulator for an adjustable one.

Paul Lamar


The problem with higher fuel pressures is that the EC2 is not good at
managing the shorter pulse widths at idle.  I don't think you will get
it to idle at all much above 40psi, the surging is really bad.  I found
everything (even high power but especially idle), ran best with my
regulator set at it lowest setting (about 32psi at idle)

Don't forget that the EC2 expects a manifold referenced regulator as
well, fuel pressure should be going up with MAP.

It does take some patience to adjust (mode 3 I believe) so secondary
injectors are not noticed when they come online.  I found I could get a
smoother transition by moving it up a little higher in the table (like
at 24"MAP).  That also helps keep your idle fine tuning well separate
from your transition fine tuning.

Transition tuning is also _greatly_ helped with a device that can look
at the map and adjust individual bins - such as Tracy's EM2 or Ed
Anderson's EFI meter.

Keep at it. Remember, its fun!  :-)