MAP sensor calibration

[bballer182]

I would think that PSIA and PSIG would be the same in this case.

I thought PSIA = PSIG + BARO


anywhere where BARO is zero will allow PSIA to equal PSIG.

Boy i was tired when i posted that... Duh PSIG = PSIA - BARO

note to self... don't post when you wake up

[bballer182]

I would think that PSIA and PSIG would be the same in this case.

I was questioning bballer and affirming your reference to space (PSIA = PSIG = BARO = 0).



PSIA and PSIG are generally defined to be related by PSIA = PSIG + BARO

(nevermind me, I'm just sweeping thru all the threads)

So has anyone explained why MAP isn't equal to BARO at sea level (I'm curious to know)...?

Isn't MAP (Manifold Absolute Pressure) supposed to be the same as BARO with zero boost and then as boost rises it reads PSIA? PSIG+BARO??

[JoshH]

Isn't MAP (Manifold Absolute Pressure) supposed to be the same as BARO with zero boost and then as boost rises it reads PSIA? PSIG+BARO??

Yes it is. I haven't played with the MAP PID much, but I know the Boost2_DMA PID matches.

[joecar]

See post #1:

Has anyone else an opinion on what the problem is here?

At or near seal level, MAP and Baro should be equal. I have noticed idle (no boost) MAP is around 12.0 psi, instead of the expected 14.x psi. Location error, or calibration issue?

This has been observed on multiple LMM's.

[bballer182]

I was just saying that no matter what altitude MAP should equal BARO

[L31Sleeper]

See post #1:

Has anyone else an opinion on what the problem is here?

At or near seal level, MAP and Baro should be equal. I have noticed idle (no boost) MAP is around 12.0 psi, instead of the expected 14.x psi. Location error, or calibration issue?

This has been observed on multiple LMM's.

It's simple there is a vacuum for some reason I don't know.

[bballer182]

could it be that the intake butterfly is closed during this anomaly?