How difficult is it to set up an ECU from scratch?
Most after market units come with software is this all one needs to get your car running smoothly.
With some effort most people who have built a locost can set carbs so what is the big mystery with an ECU.

The big mistery isn't there in fact its all a question of time

Its a question of haveing clear when you need to inject and when you have to spark. and that for every cilinder/piston

sounds easy ehhh it still isn't

Tks

scratch for me means if you want to build your own controller...

[Edited on 11/4/07 by tks]

It depends which ECU you are on about. Some are easily configurable, others need specialist software.
Setting up the configurable ones (like megasquirt) is very easy if you have a wideband O2 sensor and controller. The supplied software can predict you a base map to get you started and then there are various forms of software to analyse datalogs and suggest improvements. It can be done with a NB O2 sensor but it would be far harder and less reliable as some experience of engine tuning and how various settings (rich/weak/advanced etc)will feel on the road.

I've had a tinker on the fine adjustments like cold start mixture and rad fan control, but I wouldn't dream of trying to map anything from scratch. Ideally it needs to be done on a rolling road and requires a wide band lamba amongst other things.

If you can get hold of a base map to get you running, try and spend a few hundred quid getting it proffessionally mapped - its money well spent in my book.