Does anybody know what the RX-8 throttle body pin-outs are
and the
voltages that the sensor/s needs ? We are assuming there is
a hall
sensor in there somewhere being "Denso" it appears they
have done it
the hard way. We can simply want to use the throttle body
as it is out
of the box rather than modify it to a cable

Regards David

Try this link David
http://foxed.ca/rx7manual/2003mazdarx8/

Paul Lamar
--

Thanks, got to spend awhile hunting through checking now
and see what
it got to say :)

David

I think Tracy Crook is usng the RX8 TB un his RV8 on a 20B.
He seems to
have all the details.
FWIW.

Richard Sohn
N2071U

Looks like it takes a computer to control it. It looks
like
a closed loop servo system with data fed back from the
throttle
position sensor. It is spring loaded to close to 5 degrees
if
the electronics fail.

Paul Lamar

--

We have looked at this and it appears that it uses a couple
of
hall effect sensors so we have to tread lightly or they
will be toast
if we do the wrong thing by them, apparently using these
means that it
senses movement rather than specially position and then
something has
to hold it and detect movement and so on, TK a friend of
mine is figuring
out how we can do this I assume since he used to work for
GM in R&D that
he has a good idea or what he's talking about, as he put it
why did they
do it the more difficult way? However we are seeing what we
can do to get
a workable method, without modifying the throttle body.
WE'll see.

Tracy, I know had something or mentioned something was
coming but it has
never become available unfortunately, I did ask about it
and that was the
answer at the time as far as I'm aware nothing has changed
since or to
date.

Regards David

It is not a stepper motor as it only has two wires going to
the DC servo.
The 2004 Service Highlights book mentions "duty signal".
Sounds like
the typical NC tool analog servo to me. Plus supply voltage
rotates one
direction
and reverse voltage rotates the other direction.

There are two sensors. One is probably out of phase with
the other.
By this means an angular direction can be determined. When
both pulses
coincide
and index position is found. Encoder SOP in NC tools. See
the diagram.

The probable reason Tracy did not implement it as this
function is built
into certain microcomputers used in automotive EFI systems
with special
hardware and software to deal with servos. Tracy is a
probably using a PIC
that probably does not have this function built in.

I'll consult with my expert on this matter as I am still
learning
in the process of updating my NC mill controller.

What do you think Tom?

Also read this.

http://www.aa1car.com/library/throttle-by-wire.htm


Paul Lamar

--
Yes, There are two sensors that are associated directly
with the throttle
shaft using magnetic fields and yes we believe they are out
of phase with
each other as mentioned Yes the motor is a servo motor, Now
all I need is
a CCT that will drive it.  I'm not a electronics
circuit designer so I
have to rely on others for help and I'm not a code cutter
either, So I
have rely on assistance from others for this. I can only
build them.

Regards David

May I ask what are your plans for this David?

Paul Lamar

--
You may :) - Simply put, I hoped to be able to use the
throttle body as
it is and wire it instead of modifying it for cable I like
the idea of
using the throttle as it is. Since everything is already
driven
electronically I saw no reason not to drive the throttle
the same way
and simply use the original throttle as it was. The engine
etc is going
into a Tandem Gyro Plane.

Regards David

That is way over kill David. It will cost scores of man
hours
to get an electronic throttle working from scratch.
You don't need it anyway. It is primarily designed for
emission
reduction, automatic transmission shifting  and
stability control.
Far far cheaper just to get a throttle body out of a Ford
V8 or some such.
Or build one of our Teflon slide throttles and p-ports for
max power.

Paul Lamar

--
Well it would have been nice to do it that way.
Sigh.......Yes I know we
don't need it, we don't need the P-Ports the engine as it
stands has
plenty of power, we don't need to change the intake system
either, we have
the plenty of space to use the stock intake system which
was why I hoped
to
use the throttle body with a control circuit. I guess at
the end of the
day
I may convert the throttle body to cable which was always
on the cards
anyway.

Regards David.

It is not a trivial matter to get the stock system to work
in an AC as
there
are a lot of inputs from the transmission, exhaust system
and other parts
of the
car that the Power Control Module (PCM)takes into
consideration that must
be simulated.
Perry Mick successfully did that for a 2nd gen RX7 EFI. The
RX8 is far
more sophisticated.
The RX8 PCM actually changes the injection timing as a function of RPM.
If you don't
use the stock PCM and the exhaust system you may be
disappointed in the
BSFC and HP. It will also be very difficult to get the
stock PCM to
lean the mixture as the RX8 PCM goes rich when power is
required
and never goes lower than 14.7:1 at cruise for emission
reasons.
Perry Mick ran into that particular problem as well.
In other words it has different priorities for use in the
car engine that
conflict with the needs of an aircraft engine. An OBD II
interface
and software would be a good start to study the operation
of
the PCM in the RX8.

It is usually easier to start over from scratch with a new
intake
system and computer. Or no computer at all with a 555
analog system.

Paul Lamar

--

Paul I think something has been missed, I'm using Tracy's
EC3 and EM3, I
already have
these units, the Stock Computer is not involved and was
never going to be,
all I hoped
to do was drive the throttle body by itself nothing more.
Basically an
electronic cable,
That's all.

Regards David

Are you still using the stock intake system with all the
computer controlled
valves? High power engine or low power engine?

Paul Lamar


David -- Check with Tracy on the EM3.  The 20B powered RV8 does
use the electronic throttle.  Tracy mentioned he didn't want to
release any details until he had flown with some hours on the
system.

With an electronic throttle controller, I could build a simple
one in a few hours, as I have done this before. Building is one
thing, validating and testing is quite another.  Add support and
it suddenly becomes a 500 hour project. :)  For a vehicle it
reduces a number of subcompoents (aux air valve, cruise control,
cable and linkage - NVH reduction, in additon to emission or
engine saving mode (i.e. built into the Corvettes to prevent
your 16 you old son from borrowing the car and spinning high-G
donuts until the engine is starved of oil... hence in that case
it will reduce throttle slowly as few onramps have more than 360
degree turns!)

Older systems used an idle control valve. Simple PWM or stepper
motor to control the amount of air bypassing the throttle plate
to keep a steady idle. I did make a system to replace the BMW
VDO module, but didn't want to mess with liability, so it was
simplier to repair the OEM system than replace it with my own
controller.

With aircraft and a throttle control cable, there isn't much
need as we only are at idle a few times before and after flight.
One thing I recommend is that if the cable is detached, or slips
out of place, is for the throttle go to WOT (Wide Open
Throttle).  Much easier to return to an airport at WOT, and just
kill the engine once in the pattern. :)  I was looking at a few
Rotary Powered planes and noticed the stock spring for "return
to idle", when I asked the pilot about it he commented "never
had an issue, so it is fine that way".


Tom Walter