From: "Phil Payne" 

> > It's called "limp home mode".
>
> You're quite right. I misremembered the "Keep Alive Memory" we[*] used
> to remember engine tuning parameters while the main battery was changed.

Yup.  We actually use a diode pack derived from these cigarette-lighter
solar chanrging panels and a tiny 12V battery.

> Ended up ditching KAM because the dynamic tuning happened fast enough
> that it wasn't worth the extra hardware needed to save the results. The
> limp-home function is as I described though.

Plus you every now and then got a transient that was remembered in a
non-volatile ECU memory.

> [*]Ford Dunton, programming the EEC IV back in the 80s.
>
> > The Audi rally cars of the early 1980s actually used marine fuel
injection
> > management.  Maritime law requires a more graceful degradation in the
event
> > of failure - this is very useful in a rally car because it means a car
with
> > a "failed" system can get back to service and get it put right.
>
> On the RS 200 we ended up having to use 2 Iveco truck injectors per
> cylinder just to get enough fuel into the beast. That was an interesting
> engine management strategy.

With two fuel rails and two fule pumps?  A bit more belt and braces.  The
legendary Audi S1 of Pikes Peak fame closely resembles a truck under the
bonnet.

> > There is, IMO, a commercial opportunity in buying up cars of this
nature.
> > Fix up the limp home issue (sometimes just a cheap temperature sender)
and
> > sell the car with restored performance.
>
> I wonder how many are driving around now in permanent limp-home mode.

My guess on the Audi 1B/MB/MC/RR/3B engines - around 40,000 cars world wide
- is around 40%.

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