On Wed, June 15, 2011 6:22 am, alan.b.pearce@stfc.ac.uk wrote:
> http://blogs.freescale.com/2011/06/07/calling-all-petrolheads-configurabl=
e-aftermarket-ecus-for-sale/?tid=3DNL_2411
>
> Some guy at Freescale has designed an aftermarket ECU for his 1970s Mini,
> that he has converted to fuel injection.
>
> May interest some of the petrol heads here.

Very interesting. From my experience tuning my Miata (with an aftermarket
ECU + supercharger), the hardware is the easy part. You've got a lot of
input and output variables, and in general, just not enough sensors to put
on a roadable car. Virtually every implementation I've seen for ECUs
relies on many hours with a brake dyno to get the maps right across a
reasonable range of driving conditions. Some of the vital sensors need to
be in the nearly incandescent temperatures of the exhaust, and as others
have pointed out, emissions throws more difficulty in there.

The curves for power, efficiency, and emissions do not overlap and involve
a lot of design that goes beyond the [EE] scope of the project- for
example, the mechanical properties of injectors have a very strong effect
on how you run your system- the flow is proportional to the pressure
differential across the injector (manifold pressure, fuel rail pressure),
but since the flow of fuel has some inertia, even the placement of the
injector on the fuel rail can affect flow.

You also need surprisingly fast and large range input captures- you want a
large RPM range, but you also want good resolution throughout the range.

ECUs are challenging and very complex projects.  I'm sure we will be
seeing more, particularly on small engines.  With more powerful processors
and sensors getting cheaper, we'll probably also see less reliance on
injection and spark timing maps.

Matt Bennett
Just outside of Austin, TX
30.51,-97.91

The views I express are my own, not that of my employer, a large
multinational corporation that you are familiar with.
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