Subject: Electronic Throttle Questions
From: Rotary Engine
Date: 6/22/2009, 9:17 AM
To: AAA Put this in the To box


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 using the RX8 TB on 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

-- 

Stock intake system yes there is plenty of room height wise, sine the RPM
ranges and when valves need to be open are now known thanks, 6 port engine
typical rev range is lower for this task than used in a regular fixed wing
plane would not normally exceed 6200 rpm as simply don't need to under
normal circumstances. The valves we believe we can control based on the
RPM ranges provided using either a RPM output from the EC3 or suitable
trigger.
We think that should work OK might need a little tweaking but that should
not be too hard to do.

Regards David



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