"Brian D. Cain" wrote:

The Haltech E6 models utilize _either_ of the two rather than a combination.
I've got my particular E6K configured to the MAP load dependant.
I believe the factory Mazda EFI system utilized in the second generation
Rx-7
uses throttle position and then corrects for RPM (which is really weird?)
under
vacuum but then switches to a speed/density system under manifold pressure.

The E6 corrects based on several other variables that I won't get into.

--RPM
and the output of this calculation is:
--Fuel Flow (controlled through pulse width of the injector,
premised upon some fuel rail pressure)

Bingo.

--Spark advance

Both leading and trail split (degrees inbetween leading and trailing spark)
advance...

There are other measurements that can be helpful for *tuning* and
engine:
--Fuel/Air ratio, and/or
--EGT.

I'd rather tune around A/F ratio directly.

[As a side note, I read Tracy's earlier comment that fuel/air
mixture ratio measured by an O2 sensor was faster to react than
an EGT. This might be true but hot rodders working on chassis
dynos will tell you that the ordinary O2 sensor, while fast,
isn't accurate enough for tuning and that they prefer EGTs. There
is a special wide-band O2 sensor that is both fast and accurate
but it also costs $$$$. Before going too far down the road built
upon the ordinary O2 sensor, one might investigate this question.
If Brian Cain and John Vitamas are still on this list, they may
be able to add something to this discussion.]

I believe O2 sensors react faster than EGT gauges, but I could be wrong
about this.
They're both predicated upon the velocity of the exhaust gas exiting the
engine and
making contact with their respective sensor(s) downstream.  The only 'beef'
I've got
about the standard, Autozone (cheapy) O2 sensor is its (presumably) limited
voltage
range and output accuracy.  That's where the wide-band stuff comes into
play.

On the EGT's, however: EGT's are only as good as another referenced standard
in which it can compare a given exhaust temperature (which is further
complicated
by its location in the exhaust stream) to a given exhaust/oxygen reading.
In English,
an EGT is utterly worthless in an of itself, in my opinion.  If you've got a
set of numbers
or data to create a standard of comparison that reflect A/F ratios, then
they're not
useless (as much).  But, if it were me, I wouldn't trust it 1/10th as much
as I'd trust
a wide-band sensor on a chassis dynamometer for tuning under heavy load.

The display on the E6 models (unfamiliar w/ the F9) displays an array of
outputs:
(off the top of my head)

- Engine RPM
- Manifold Vacuum/Pressure
- Throttle Position
- Coolant Temperature
- Battery Voltage (yes, the ECU corrects for this believe it or not)
- Inlet Air Charge Temperature
- Injector Time (ms)
- Advance
- Trail Split Advance (for rotary)
- Air/Fuel Ratio (O2 output)
- O2 loop (open vs. closed)

I'm not sure how this helps you fly boys out there, but it's a great big
help to me
when I'm t-shooting a problem in the garage.

I think that's the list of helpful stuff to know about the
engine.

<big, humongous snip, yeow!>

B

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