Air/Fuel Question

[jdbubb@ix.netcom.com (Dan Bubb)]

As long as your engine runs fine without missing while cruising I
wouldn't bother trying to richen it up.
With CIS (i.e. NOT lambda or E) there really isn't any way to change the
mixture aside from messing with the control pressure and from my
experience that is a real hairball.
Changing the idle mixture will have a minor effect on the mixture once
the throttle is opened even a small amount. eg. if you change the
mixture 10% at idle then doubling the airflow (say doubling the idle
speed) reduces the % change to 5%, with 5 times the airflow the % change
is only 2%. So, the effect of adjusting idle mixture dies out quickly as
the throttle is opened.
Personally, I think your a/f readings are interesting but not indicative
of a problem.
Dan

Cory Langford wrote:
> 
> Okay, I have small conundrum I am working on and maybe someone here can
> throw some info at me to help out :)
> 
> I installed a cheap autometer air/fuel meter into the '79 with a 1 wire o2
> sensor.  At start up everything seems normal. I get a rich reading, as I
> expected due to the cold start injector kicking in.
> 
> When it is warm and under load it runs just shy or rich.
> 
> What I have noticed is that when I am simply cruising along a 2,0000-2,500
> rpm and the engine has no real load, it leans out right to the end of the
> scale.
> 
> Step on the gas, back up to stoic just before rich.
> 
> I can see it getting lean when you take your foot off the gas as engine
> winds down, but once at a steady rpm I thought it should go back to stoic
> again.
> 
> I am going to try and richen the mixture a bit, but I can't seem to think
> how to get it richer just at the lower rpms (unless I am thinking wrong
> here) with out richening out the upper rpm range.
> 
> Any ideas?
> 
> Thanks
> 
> Cory Langford
> '86 turbo project - running, just needs tuning :)
> '79 daily driver - Restore in progress...
> '65 Ghia - The next project in the garage
> 
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