[DeTomaso] EFI

[gow2 at rc-tech.net]

I have a Holley Commander 950 on my MG...I should say had. Tuning was not
hard but it was tough doing it by yourself. Laying laptop on the seat,
trying to read it when you take off, decel, etc. Trying to see what it was
doing.

Here are some things I learned.

If you are out of range with the O2 sensor (rich), it gets dirty. Once
clean it may not read the same as dirty.

OEM set ups are close and not really meant to be very far from close and
may not compensate correctly if you exceed the parameters it was designed
for. Let it carbon up an O2 and it will never get right.

You see guys throw turbos on OEM engines and they go lean because the
system is designed to compensate a little up or down and they end up
leaning out the engines.

I played with this open loop and closed loop with a wide band. I watch
what it did. I was able to get it closer open loop then closed. Here is
why. You can watch the close loop sort of chase it's tail. A little lean,
compensate, a little rich at a different spot then wag back and forth. It
works fine with steady throttle, but move the throttle around (like when
you drive) and one compensation messes up the next parameter a little and
it bounces around more. I turned off the closed loop and I was able to get
it far more fine tuned.

Keep in mind, compensation for O2 is not limitless, just adds or subtracts
a little up or down.

The nice thing about the system is you can tweak EVERY aspect and it runs
as good as you are willing to work with it.

Move to newer systems. The feed back loop does not change on the fly, the
feed back re-writes the map!!!! That is important to understand because
instead of reading a rich or lean condition, compensating for that
parameter then waiting for the results, it is simply a closer result the
next time it hits that parameter! That is what makes the newer system so
great.

The MG? I just had the engine out for other things and I am going back to
car. Why? I did not do a good job with the FI wires and my car look like
it had an octopus on the engine. I am going back to the clean look. Plus I
like tuning carbs too. There is a lot more to a carb then just getting the
jets right.

Gary





>
> Question: Are any of those EFIs closed loop? That's how OEM works, and if
> it
> is, then tuning should be unnecessary
>
> Mikael
>
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