> Very educational to watch the display.  "Sweet spot" setting of mixture
> (on 77 CIS engine) is very narrow and has nothing to do with best (ie
> stoichiometric) setting at idle.  I can't imagine pulling the plugs often
> enough to get it right without a tester that can go on the road.  Does this
> match the experience of others -- that CIS system is rich at idle in order
> to be neither rich nor lean at speed?  Or do I need to install clean plugs
> and try again?
> 
> B.
> 
Well, I had mine origionally in my '76 and agree entirely, the D? or L?
jetronic always ran rich at idle and very slightly lean under load to get
the best power and fuel economy, in fact very good economy, as the girl
I sold it to is getting around 20 mpg or slightly better on average,
BTW I did all my tests with brand new Bosch Platinums as I got a set on sale
for $1.50 each.  Now on the '76 the idle air
bypass screw had a great role in the idle mixture as well, if I used it to
flow a lot of air by, I got high revs at idle 1500-1700 say but a nice
mixture, to be expected I guess, and of course when I brought her down
to 1000 or so it ran rich and fooling with the mixture control would
only detriment the running under load making her much much too lean, I'd
say you got it just right, see how your fuel economy is and watch for
overheating if it is too lean.

John Anderson
ja@coe.wvu.edu
'71 Westy, '90 Corrado G60