Multimeter (was Re: '86 C-GT Alternator...)

[Phil@isham-research.demon.co.uk (Phil Payne)]

In message <9708082048.AA41756@fluhr.austin.ibm.com> ejfluhr@austin.ibm.com (Fluhr) writes:

> > Hmm.  Not here, they don't.  We don't even have closed loop operation on CIS-E
> > in Europe.

Don't forget that we had no OXS sensor in the European ur-quattro until
the 20V came on the scene.  There is no mixture control feedback in
the WR or MB CIS-E systems.  The ECU looks after ignition timing,
keeps a watchful eye on maximum boost (ready to cut the fuel pump),
provides information to the idle controller and controls the cold start
valve.

In the WR, open throttle enrichment is entirely mechanical - there are
no electrically operated devices in the system.  In the MB, there _is_
a dwell valve in the return line under ECU control.

Both the WR and MB, when they leave the idle state at which the CO values
are set, are essentially flying blind as far as mixture is concerned.
This is why it is _SO_ imprtant, especially with the MB, that the CO
settings are achieved correctly.  If the CO adjustment is used to
compensate for system deficiencies (leaky cam and crank seals, worn
metering head) then the air and fuel volume increases will not track
together through the throttle range.  This lack of feedback is, IMO,
a most serious deficiency with increasing engine age.

--
 Phil Payne
 phil@isham-research.demon.co.uk
 Phone: +44 385302803  Fax: +44 1536723021  CIS: 100012,1660