MAF and SD (was re: Re: New member intro)

[Bohdan L Bodnar]

>> Speed density systems that I know of include a barometric pressure sensor.  I
>> don't really know who the audience is here yet, so if my comments are to 
>> generalized or simplified I apologize.
 
>GM speed density uses only MAP.  Did Ford's aborted attempt at speed
>density use a BAP sensor?  (the worst comments I've heard about that
>system have all come from Dearborn :)

 
>-- 
>Jonathan R. Lusky                        lusky at knuth.mtsu.edu
>http://frank.mtsu.edu/~lusky/               (615) 726-8700
>-------------------------------------   ------------------------------
>68 Camaro Convertible - 350 / TH350  \_/ 80 Toyota Celica - 20R / 5spd

*ALL* SD systems require a barometric pressure reading.  On GM, Ford, etc.
the reading is taken under two conditions:  (1) engine cranking (when MAP is
close to BP) and (2) close to WOT.  Early (GM) CCC systems for carbureted
engines also used a "baro" sensor.  The baro sensor is nothing more than a MAP
and BP sensors with an analog subtraction circuit to output the difference of
the two.  The really early stuff used separate BP and MAP sensors (made by
Bendix).

I'm not so certain that Ford's "attempt" at SD controls is "aborted";  almost
ALL the Ford stuff that's rolling on the roads is SD and it certainly appears
to be functioning properly.

Regards,

Bohdan Bodnar