re. factory instrumentation accuracy & mpg

[ben swann]

Yes - peeve # 2 on the new aquisition of the '91 200 20v tq avant.  Has
SJM chip with 2.5 bar pressure transducer AFAIK.  Gas mileage abysmal
on the way home - 20MPG and no I was not easy on the gas and probably
averageing over 70.  My '87 5000 tq would get an easy 28 mpg under the
same conditions.  I thought Motronic was supposed to be superior at
engine management, including economy, over CIS (CIS/motronic).

What's up with that?

Ben

[Does anyone know how the driving computer arrives at the number it
alls average MPG?  It definately has NOTHING to do with actual fuel
flow!  Does it do it's calcs based upon stored parameters and ideal
situation testing done at the factory?  Is there any way to recalibrate
it?  BTW:  My fuel burn (not to be confused with "fuel economy")  after
the eprom upgrade,  is now about 11 to 14 miles/gallon.  I realize some
of the reduction is my occasional use of my newfound power,  but it's
not much better when I drive it gently.  Any one else have this
experience?]