Re: EEC-IV

[Brad Sheridan <brads@mindspring.com>]

At 09:06 AM 10/18/98 EDT, you wrote:
>ahh, this is interesting.
>The EEC is tunable, with performance chips (actually mount downstream of the
>computer as when you actually change the chip the computer learns and changes
>back) and after market ignitons(including retard controls) work well with it.

I have seen stuff that you can buy that is much more than a chip. It allows
you to individually program whatever it is that you want to adjust. I think
it was on the DIY_EFI mailing list that I saw it. But it looked as though
it allowed pretty much complete control.


>It would be neat to adapt this system to a rocco but IMHO this would be an
>incredible PITA. Each individual car has a different computer- mustang, crown
>vic, pickup- they are all different. plus adding all those sensors...

Most wouldn't be too hard, the hardest sensor to add would be crank
position, but then for most aftermarket systems you'd have to add it anyway. 

>oh, and one more thing, the 86-89 EEV-IV systems on the mustang, as well as
>earlier systems on other cars (CFI on Crown Vics and LTD's) is Speed density.
>this sucks. you want the mass air system, 90-93 mustangs have it. and stay
>away from the MCU system (came of 351 windors with VV carb and a few others)

  Speed Density is nice for turbocharging it helps reduce lag, from what I
gather. Speed Density uses engine RPM, and intake charge density(calculated
from manifold pressure and temp. (MAP & MAT) sensors. Whereas Mass air
systems use the mass air flow(MAF) sensor, which is located near the
beginning of the intake system. On cars with turbochargers, this can lead
to a good bit of inaccuracy due to the fact that the MAF sensor is located
so far away from the cylinder head. This can allow the manifold to act as
abit of a damper between the air flow at the MAF sensor, and the actual
amount of air going into the engine. The downside of Speed Density is that
it would require a much more complete retune of the ECU, as it relies on
the volumetric efficiency(VE) of the engine in its calculations. Change the
VE, and you have to change the fuel maps. Even on Mustangs with the speed
density EEC-IV, simply changing a cam or header changes the VE, requires a
remap of the chip. Mass Air Flow systems do not use calculations to
determine the amount of air entering the engine, they just measure the
flow, So you can do alot of mods to a MAF system, and not have to remap the
chip. This could potentially make MAF systems much simpler to setup, and
given your relatively(to a V8) low power goals, it should work without too
much problem. Be aware that one problem with MAF systems is that the MAF
sensor has a limit to how much it will flow, but I think your hp goals,
even with turbo are well within this limit.

Brad

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