Thanks for the note about fuel injected Jags running rich
when they are cold. I recently acquired a fuel-injection
manual that describes how the Lucas/Bosch Jetronic units
work. The D-Jetronic and the L-Jetronic are about the same
in function but different in design. The D uses discrete
components where the L uses LSI's (large scale integrated
circuits). The L unit has only about 80 parts where the D has
over 300. Therefore, fewer solder joints, etc...
But to the point; The FI automatically dumps extra fuel into
the system via cold start injectors that are the equivalent
of single-point fuel injection systems. That is, they inject
from a central point and allow the inlet manifold ducting to
handle the distribution. The cold start injectors stay on for
only about 30 seconds controlled by the coolent temp, air
temp and by the thermo-time sensor. (I always wondered what
a thermo-time sensor did. It appears that it is like any
other binary sensor in that it has two states - off and on.
But unlike the other devices, the on state is timed to
about 30 seconds after which it's two states are off and
off.) Hense the 20+ seconds of rich running that you mention.
I like it when theory and observation converge!
Have fun,
Rick
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Richard O. Lindsay / __ __ __ __
Senior Research Scientist / / /_/ /_ / / /_/ /_/
Amoco Production Research / / / / /_/ /_/ / / / \
/ /_/
/
My opinions are my own, until they're worth something, at
which point they become the property of my employer...
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