DeTomaso Mailing List: February 2001, Message #52

Kirby,

The FAR is the Fuel Air Ratio. The knowledge of the time a cylinder's
pulse of gas takes to travel to the O2 sensor, a single sensor can
measure each of it's four cylinders, not just the average. Knock
detection is separate and not present on most Ford engines. My Cobra
DOHC is one of the ones that have it. As far as I know it is not used
for tuning, just as a safety device that backs off advance (rather
drastically) when knock is detected.

Richard

Kirby Schrader wrote:
> 
> Richard,
> 
> See! I knew someone out there would know more about this EFI stuff...
> 
> But, errr.... uhhh... what be 'FAR'???
> 
> Two O2 sensors would still be each averaging four cylinders on a V8.
> Or is the FAR thingie something to do with knock detection? That's
> the only other sensor I know about on the engine which has something
> to do with ignition/fuel-air.
> 
> Enlighten me some more!
> 
> Thanks,
> 
> Kirby
> 
> At 23:59 -0500 31/1/01, Richard Barkley wrote:
> >Kirby,
> >
> >The Ford EEC-V (which is BTW much more sophisticated than the Chebby
> >ECUs) has the capability to sense the FAR of each cylindar's pulse. In
> >order to accomplish this on a variety there is a paramater to tell it
> >the delay time to expect from spark to pulse. Thus the two O2 sensors
> >are sufficient to do the measurements. According to my sources (Mike
> >Wesley primarily) there is a quasi capability to then adjust the
> >individual injectors. Not sure exactly what this is but my guess is that
> >since the EEC is a "learning" system, it learns how much each cylindar
> >is off and adjusts things accordingly in an average sense (not stroke to
> >stroke).
> >
> >Richard
> >
> ><snip>
> >>  The Haltech does batch fire at any rate you pick based on number of
> >>  cylinders, etc. And the Haltech also controls the injector pulse. All
> >>  EFI's would have to do that, I would think...
> >>
> >>  I can see why such a system would be expensive if it was dynamic.
> >>  You'd need a sensor on the intake and exhaust of every cylinder for
> >>  feedback to the ECU.
> >>
> >>  Wow.....
> >>
> >>  Even adjusting the system would be the mother of all EFI adjustments...
> >>
> >>  Tell me more!
> >>
> >>  :-)
> >>
> >>  Kirby
> >>
> >