Bohdan.L.Bodnar at att.com Bohdan.L.Bodnar at att.com
Wed Mar 6 13:43:09 GMT 1996


>Bohdan Bodnar wrote:
>
>> GM and Chrysler MAP sensors have an output which is roughly between 0.1 and
>> 4.9 volts. 
>
>This is to allow for mfg. tolerances to gurantee that any given unit will
>be within the 0-5V input range of the a/d converter.  The zero offset also
>provides a little headroom for noise immunity.

Actually, the voltage ranges are to allow the computer to test to see whether
(1) the output's shorted to ground or (2) whether the output's open (i.e.,
voltage higher than about 4.9 volts).  Noise immunity is achieved by low-pass
filtering the signal.

>> Ford's MAP sensors (and BMAP sensors) output a variable frequency.  At 
>> atmospheric pressure, the frequency will be between 155 and 159 Hz.
>> About a year ago I posted a table which gave output frequency vs. pressure 
>> for a Ford MAP sensor.  
>
>Would you kindly email this to me, if you still have it kicking around? 
>Actually, post it to DIY_EFI, there are probably more people who would like
>to see it.
>
>regards
>dn

I don't have it readily available.  Time permitting, I'll dig it up (it's from
some Ford training material) and post it early next week.

Cordially,

Bohdan Bodnar




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