Still not 3 bar but a little better.
Gm 3 bar map sensor voltage chart.
039 460 883 876 2 bar.
It shows right on the chart top part idle to be to the right side high vacuum low map voltage and left to be wot low vacuum high map voltage.
Formula for the gm 3 bar map sensor is v 8 94 14 53 i have no idea why it s 14 53 and not 14 696 rounds up to 14 7 but it works out on gm s chart every time.
This means the output voltage of a 2 bar map sensor with the key.
749 861 the logic module uses the manifold absolute pressure map sensor to determine the absolute pressure not the relative to atmospheric pressure of the air inside the intake manifold and the atmosphere barometric pressure.
I m betting either a bad map sensor or the wrong part altogether.
Now at a slightly higher elevation reading flickers between 1 78 and 1 79v giving a reading of 0 9 psig engine load with the car off.
So by supplying a higher or lower voltage the return signal is varied by the same amount.
Apparently it s a gm cheverolet performance 3 bar sensor which should have an approx.
The op stated the map voltage was high at idle and went down as vacuum decreased.
I have looked around to try and find the calibration data for the gm so that i can choose custom 3 bar and get it to work up to 31 2.
Why doesn t it give me the full 3 bar of resolution.
So in order to accomplish this the output voltage must be scaled accordingly.
3 digit numbers for identification.
The map sensor manifold absolute pressure has a 5 volt input and then reduces this voltage according to throttle opening altitude etc and sends the signal to the ecu.
On my fuel table it only goes up to 26 8 psi.
This is the opposite of what should really happen.
It is possible that detroit is slightly above sea level and you can use 12 11 in the formula for 1 mile above sea level.
Linear output based in this info chart shown is for a 2 bar scaling to 29 4 psi.
A 2 bar map sensor will read up to 2 bars of atmospheric pressure difference and a 3 bar will read up to 3.
If i choose the holley it goes to 31 2 psi.
Gm map sensor identification how to identify a gm map sensor.
Formula for the gm 3 bar map sensor is v 8 94 14 53 i have no idea why it s 14 53 and not 14 696 rounds up to 14 7 but it works out on gm s chart every time.
It is possible that detroit is.
