ECU

[Huw Powell]

> CIS-E,
>
> When in open loop does the ECU gets in preset values for differential pressure
> regulator (8-10 mA) , with no fluctuations?

Yes, basically.  In open loop the current is fixed by the ecu - when the
engine is cold, it is higher than that, though, to provide enrichment.
When the WOT switch is closed it is also in open loop, with a slight
enrichment to help you accelerate.

Perhaps there is also a default for warm engine and no OXS signal, but
there might not be, since that is not a "normal" operating condition.

The fluctuation in closed loop is due to the ECU constantly adjusting
the mixture slightly in response to the OXS signal, so the engine is
always veering a tiny tiny bit rich or lean - but very close to perfect
mixture.

The later CIS E3 cars fluctuate around 0 mA, so in the case of no power
to the ECU, they are capable of limping along ok - though not very good
at starting when cold.

You might want to do some searching of the archives, as I'm sure at
times myself and others have written detailed explanations of how
CIS-lambda systems work; there is also my web site which might be
helpful.

--
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/