Paul,
I'm forwarding an old email relating to the CAS mis-fire problem.  It is
interesting that you saw 40v when you went to a narrower gap.  That is why
we used a zener diode between the sensor and the EC-2.  Using a scope Bobby
Hughes monitored the CAS output voltage while I ran the engine (don't worry,
he had long leads on his scope).  We were seeing greater than 30v.  The
zener clips the voltage to about 8 or 9 volts (best guess).  Dennis H. had
to do this with his Renesis.  That's where we got the idea.  The problem
with a wide gap is that it won't start.  There's got to be a happy medium
somewhere.

Mark

I think that is a big mistake. Tracy relies on the exact shape
of the wave. If you clip it with a zener you will get a distorted
wave. I would not do that. Here is a scope picture of a diode in
series.

There are two polarities possible.
You obviously lucked out as the engine still starts.

Typically micro computers use only half the wave.
The upper half or the lower half. The wave is processed
by circuitry before it is sent to the computer as a simple
5 volt pulse. Here is a schematic for a circuit
that takes in a CAS signal and converts it to a neg pulse.

I don't have any zeners so send me one of yours and
I will test it.

Make yourselves a bracket where you can adjust the spacing.
Open it up until the engine does not start.

Paul Lamar

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Milo,

Sorry, but I can't check the resistance of my CAS as it is hard wired into
the harness and then potted.  I didn't want the big fan in front to stop
turning because a connector came off.  However, I do have a friend that has
one that he can check the resistance.  I'll ask him next time we talk.  That
should be this weekend.

BTW, the Renesis CAS is also used on the Mazda Protoge.  The Protoge has two
engine options, and the CAS's are different on each.  Sorry, I don't
remember which engine matches with the Renesis' CAS.  I mention this because
you may want to check the wrecking yards for an inexpensive spare to plug in
and try.

If you have access to an oscilloscope you can easily verify if the CAS is
putting out a good signal.  This would be a sure-fire way to verify the
CAS.

Thanks,
Mark

>      >         As for the ignition, it is doing fine, now that I figured
> out
>      >     what was
>      >         causing my misfiring condition at high rpm (6500 & up).
>      >
>      > snips.......................
>      >
>      >         Other than that, it flies great!
>      >
>      >         Mark S.
>      >
>      >  snips....
>      >
>      >
>      >         Mark,
>      >
>      >         Sorry, I must have missed the info on your ignition
>     problem.  What
>      >         was the cause and solution to your high speed missing
>     condition.
>      >
>      >         thanks, Joel
>      >
>      >
>      >
>      > Joel,
>      > A little history on my ignition problem.  Originally, it was
>     using the
>      > old style CAS, the one that resembles a distributor.  I had the
>     idea of
>      > changing over to the new Renesis style (fewer moving parts, 2 lbs
>      > lighter).  So, I purchased the necessary parts and did the
>     conversion.
>      > I had to send the EC-2 back for upgrades anyway, so it seemed like

> a
>      > good time to have Tracy change it over.  The mods included the
>     snubber
>      > upgrade to solve the injector dribble problem.
>      >
>      > Well, when I got it back, it ran beautifully in the lower rpm
>     range, but
>      > wouldn't run in the upper ranges.  We ended up installing a zener
>     diode
>      > circuit and played around with resistor values until we got it
>     running
>      > much better.  This is what another Renesis builder did and it
>     fixed his
>      > problem.  Anyway, I thought we had it handled, until I started
> doing
>      > fast taxis and I got into the 7000+ rpm range.  The misfire was
>     back.
>      > Many phone calls to Tracy, and after trying many, many things,
>     none of
>      > which helped, I was ready to change it back to the old CAS.
>      >
>      > The last thing on my list of things to try was the CAS
>     bracket.  Why the
>      > bracket?  Well, I remembered reading in the Renesis manual on CAS
>      > information and they mentioned to beware of metal filings/powder
>     on the
>      > CAS.  I got to thinking that if it was that sensitive, maybe my
> 4130
>      > bracket might be causing the problem.  So, I fabbed up a bracket
>     out of
>      > aluminum and tried it.  Would you believe it, that was the
>     problem.  It
>      > runs great now and I couldn't be happier.  So, if you decide to
>     convert
>      > to the Reneisis CAS, make the bracket out of aluminum, not steel.
>      >
>      > So, now you know "the rest of the story".
>      >
>      > snips... info later
>      >
>      > Thanks,
>      > Mark
>      >
>      > Thanks Mark on the CAS steel bracket bit. Amazing. Who would have
>     thunk?
>      > :)
>      >
>      > Paul Lamar ...No rotor no motor.
>
>     Mark I am suffering a similar problem. No ignition on an RX8 with
>     the the
>     standard CAS and RWS system. Would you please explain in laymens
>     terms about
>     the Zenior diode and resistor, actual values and a diagram would
>     help. What
>     is the internal resistance of your CAS? What is the output voltage
>     of your
>     CAS at cranking speed? As  you know my CAS bracket is aluminum of
>     course, it
>     came with the engine. No filings on the CAS sensor, cranking voltage
> not
>     less than 12V, battery ground lead does not pass even close to the
>     CAS, etc.
>     Who was the other Renises builder and his e-mail address please?
>     Thanks, Milo
>
>     Where do you live Milo? Perhaps we can find somebody with a scope to
>     help you
>     out.
>
>     Paul Lamar
>
>
>
> Milo,
> According to Tracy, the zener circuit is now built into the EC-2, so I
> doubt that is the problem.  Besides, it only addressed the issue of
> overdriving the trigger circuit at higher rpm.  Have you checked your
> wiring to make sure that everything is wired correctly?  Have you
> verified that the CAS is not wired backwards (I made that mistake
> initially).  Have you checked the CAS signal with a oscilloscope (you
> may have a bad CAS)?  Have you verified that the CAS connector is making
> connection with the CAS pins?   What is your gap between the trigger
> wheel and the CAS?  The gap on my CAS is .020".  Too big a gap will
> prevent it from starting (don't ask).  Do you have 12v to the coils?
> Have you tested the injectors and coils in the simulation mode?  Are all
> of the ground leads connected to the EC-2 and to ground (Yes, I made
> that mistake once too)?  Is the d-sub connector making good
> connection... any bent pins?   Do you have fuel pressure to the
> injectors?  Finally, have you spoken with Tracy (he's back from
> Colorado)?  I would make a list, verify everything on the list, then if
> it still doesn't start, call Tracy.
>
> There has to be a reason why it won't start.  You just need to find the
> needle in the haystack.
>
> Mark S.


Mark,
It would appear to be wired correctly.
Tracy said even if the CAS was wired backwords
it would still fire. It appears to be wired correctly.
Have not checked the CAS with a scope. The CAS
has 105 ohm resistance, what is the resistance of you CAS?
Have not verified the CAS pins.
Trigger gap is .032.
A full 12v is available at the coils.
The injectors and ignition check bright in simulation mode.
As best as I can tell all grounds are at the same level.
Have not checked the d-sub connector.
Fuel pressure is to the injectors.
Will continue with your suggestions, thanks a million.

Milo

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