injection timing

[Dave J. Andruczyk]

> Actually the CIS (K-jetronic) is closed loop.  The system pressure is set

No it isn't,  the closed loop version is K-jetronic with lambda ( which is
on your 911,  but not on my 924.

> up to run rich (good for WOT) and leans the system out to stoic by letting
> some air 'leak' around the metering flap (or is this the 'freq valve' you
> refer to in the KE-jetronic?)  Anyway, the only real difference in leaning
> the mixture and lowering the fuel pressure is that you could probably
> reduce the idle speed a little bit more in the fuel-P system.  My 83 3.0L
> 911 (last year w/ CIS) used to idle at 800-1000 rpm, but now w/ a K&N air
> filt idles at 1500.  Something about improved flow;)  BTW, it still idles
> at 800-1000 at startup, but runs rich until the O2 sensor heats and puts
> the system in closed loop;)  I SHOULD go in and set the idle speed better
> by adjusting the flap or throttle body, but what's wrong w/ running a
> little rich at startup;) (BTW, I also have the air-intake pop off valve to
> keep the rare backfire on VERY cold mornings from blowing up my airbox).

To set the idle on yours, there is a bypass air screw somewhere near the
throttle butterfly.  DO NOT adjust the sensor plate, or you'll really
screw up the mix throughout the band.  There is an allen screw somewhere
on the air flow sensor assembly. ( visible thru a tiny hole, 3mm in size)
that controls the "general fuel mix", and is used to set Base CO
adjustment ( usually at idle.)


Dave