Well, I'm glad I decided to expose my ignorance and ask this question about
fuel injection. I have spent many hours, on cold winter days, sitting in the
Barnes and Noble book store reading books on fuel injection, trying to figure
it out, only to get PO'd and switch to some other book and look at hot rod
pictures instead. This site is great. You guys have managed to explain this
voodoo stuff in terms that even l understand. Thanks
Dick J (Still running an AFB!)
Rick Byrnes <Rick@rbmotorsports.com> wrote: No one has responded to how the
efi systems vary, so I'll put in a little.
Since I know only the "Ford" system and the Accel/DFI unit loaned to me.
Both units were "batch fire, or what we call continuous flow, but just
metered, by effectively changing the orifice in the injector. (duty cycle).
With systems like this we can still get in trouble with overly rich
conditions when using really large injector sizes to make fuel air ratios
correct at the high end. Granted the map sensor adjusts for altitude, and
the coolant temp sensor adjusts for cold start and warm up, but the range of
authority on the older units makes them a large step above the mechanical
systems, but not a giant leap, as the spark and fuel tables were on the
small side.
Lately of course is sequential systems, with injector drivers enough for 2
injectors per cylinder, and the ability to adjust everything because of
greatly increased computer capacity and speed. The newer units have the
ability to run with a wide band O2 sensor in feed back mode, which means you
can basically call for a fuel air ratio, and you get it. The only problem
with this system is lead contamination and failure of the O2 sensor, since
all the racing fuel I run has the max allowable lead content. (4.6
g/gal)(I think). The solution to me is develop the calibration with the EGO
and then go open loop to race. With our old system that is what we have
effectively done for the past 12 years since that was all we could do.
In my opinion, the difference in the timed mechanical system, (Lucas,
Bosch), and state of the art aftermarket EFI is adjustability. The "problem
with state of the art EFI, is that you need one crew member as the "expert
tuner/calibrator" There is just too much to know to be able to do it all.
(for me anyway)
We can discuss the tuning changes to do based on the data collected, but
only one guy has access to the computer.
Well, after reading this it seems to me it really doesn't say much, and I'm
inclined to cancel it, but will send it anyway.
Rick Byrnes
never, never, never, never, never give up!
Yahoo! Health - your guide to health and wellness
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