First Look Pressure Transducers

Just a question about "First Look Pressure Transducers"
I was reading an article the other day by some Guru & he stated that the capture of an intake waveform shows negative pressure as a rising pattern (increasing voltage) I was always of the opinion that it was the reverse ie: rising pattern=positive pressure=increasing voltage therefore downward pattern the opposite : downward pattern=negative pressure=degreasing voltage.
Any ideas/facts to solve my query?
Thanks Kerry.

Kerry,

It's good to keep in mind that the FLS is not a pressure transducer. It's a pulse sensor that only detects changes in pressure. Any steady state pressure positive or negative results in a zero output.

When pressure is increasing the FLS deflects in a positive direction and when the pressure change is decreasing the FLS deflects in a negative direction.

Here is an example of the FLS and the Pico WPS 500 to illustrate. A is FLS and B is WPS.

I have however seen FLS that were wired backward.

Thanks Tom,
That example is interesting. While the WPS shows actual pressure going form zero to negative the FSL can give the impression that the pressure is going positive when in fact its just the movement from one state to another.
Kerry.

kerry,
i could very well be wrong, but i'm gonna add this little bit anyway. i believe the RED senx sensor that is hooked into the fuel rail works the way you described. it shows a positive pulse for a pressure drop, and a negative pulse for a pressure rise. this is going off of memory, so please forgive me if i'm wrong .

Exactly, Kerry. And the amount of the FLS voltage deflection is dependent on the amount of pressure change and the rate of change.