[Diy_efi] And for the bottom end of the market....

[Adam Wade]

--- David <d_cottrill at iprimus.com.au> wrote:

> At the moment only manifold vacuum and idle switch,
> not sure if I have to use throttle postion as
> well.... 

For a single-cylinder, manifold pressure won't even
necessarily be useful for controlling the fuel
pressure regulator.  I have been chatting with
Cannondale, and the people who developed the EFI
system for them, and they used a "vacuum" upstream of
the throttle for controlling the pressure regulator. 
For a big single (or even a small one), alpha n is
really the best way to go, since it is really
difficult to figure out a time window for useful
manifold pressure readings, especially at or near
closed throttle.  You'd be better off losing the
manifold sensor than skipping the TPS.

> At the moment I'm just trying to emulate  the
> carburettor

Since carbs have accelerator pumps more often than not
(not often on slide or CV carbs, but those also differ
from plain throttle bodies), a TPS would be the easy
way to go, unless perhaps you want to leave the stock
carb in as an air control device.

> so if I can just use a reference array instead of
> having to compute everything that would seem to make
> everything much simpler.

With alpha n, you will have a base map table that is
an array (engine speed vs. alpha), plus some "accel
shot" computations based on delta alhpa, and a
modifier/multiplier based on IAT and CHT.

> Tuning is going to be a trial and error situation as
> my workhop is about as complete as any other chef
> (this will change in time).

I'd suggest finding a way to get pretty close on the
four corners of the map and interpolate the rest. 
This should get the thing to at least run, and you can
tune from there.

> Other sensors to come later: engine temp, exhaust
> oxygen, tacho, knock sensor.

If you want to KISS, I'd use the O2 sensor (WB) as a
tuning device and then take it out; I'd skip the
knnock sensor, instean perhaps retarding timing or
running a bit too rich if you have too high a CHT. 
You'll also need some way of reading engine rpm for
the ECU, so plan on a "tacho" sensor.

=====
| Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
|   http://y42.photos.yahoo.com/bc/espresso_doppio/lst?.dir=/   |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |

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