GM MAP Sensors

[bruce plecan]

For those of you working on the OpAmp Foolers remember
the ECM looks at the MAP before start up to figure out 
what the rel baro pressure is, at least on the 747 series,
so the op-amp should be "on" only with the engine
running. Or ya will have some hiccups, or at least I did
when using a resistor divider setup to try to fool the ECM
about the vacuum signal.  I tried a ten step TPS divider,
and it was notchy, to me.  
HTH   Bruce