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Boost/ pressure readings question.


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I am after a hopefully simple answer.

I have a thunder ecu and AEM cd7 dash.

The ecu is setup to read metric(PSI) and so is the dash, but my boost/intake manifold pressure is reading in positive reading while at idle( my case 9psi on idle).

Am i to understand its reading this number 9psi because atmospheric pressure = 14.7psi , so take away my vacum at idle ( in this case 5.7psi), and i end up with a 9psi reading at idle?

I mean the ecu does the same thing, to figure out my boost pressure, i have to always minus the 14.7psi of total.

Is there a simple way to delete the way the ecu see's this 14.7psi atmo? can it be setup to read in negative for vacum, and positive when under pressure? basically the same way a normal gauge would work if you hooked it up?

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It sounds like you are viewing the parameter MAP (Manifold Absolute Pressure) which means 0Psi is total vacuum, 14.7Psi is standard atmospheric pressure at sea level and boost would be some number larger than 14.7.  If you want to see -ve numbers below atmosphere (vacuum) and +ve above atmosphere (boost) then you want to use the parameter MGP (Manifold Gauge Pressure) instead.  Both options are available in the ECU software and both are transmitted to the dash.

BTW, you aussies must have a funny metric system with metric PSI's...

Edit, added later:

It looks like AEM call the channel you want to display "BoostPress"


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haha sorry, i realised PSI is not metric, but i hate KPA so i use the USA Imperial for pressure haha, the rest is metric like speedo etc :)

Yes, using MAP...Ok, ill try to see if i can find this MGP in there, thanks alot, i knew there must be something im doing wrong :)


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Ok, i found the MGP in the Links software, so i added it for logging wich will make it much easier for me when viewing logs...awesome.

However, i cant find MGP when im searching it in the AEM dash softwhere! to add it as a stream.

Theres intake manifold pressure (MAP)( wich ive been using )

And there Boost pressure, could this be the one thats MGP?

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