Manifold pressure problem

[Drachonyx]

When boost goes over 21.4 psi on my scan gauge (bought in January from xtconcepts, version 1.4 I think), I get negative readings like -29.6 or -26.x. Looks weird. Anyone got the same problem?

[catlin987987]

hmm .

[forcefedjunkie]

Quote: Originally Posted by Drachonyx

When boost goes over 21.4 psi on my scan gauge (bought in January from xtconcepts, version 1.4 I think), I get negative readings like -29.6 or -26.x. Looks weird. Anyone got the same problem?

The stock MAP sensor will only read up to around 18 psi, a 3 bar (Stage 3) can read up to 29 but the PCM will not send a valid response above around 22 psi. To learn more do a search in this forum, there have been other in depth discussions.

The easy way around this is to connect an external 3 bar MAP to an analog input, then you can read boost up to 29 psi. If you want to go higher than that, we also have 7 bar MAP sensors.

Todd

[Drachonyx]

Quote: Originally Posted by catlin987987

its called vacuum

Did you notice that I said "When boost goes over 21.4 psi" in my first post?

Quote: Originally Posted by forcefedjunkie

The stock MAP sensor will only read up to around 22 psi, anything higher and the PCM does not send a valid response. To learn more do a search in this forum, there have been other in depth discussions.

The easy way around this is to connect an external 3 bar MAP to an analog input, then you can read boost up to 29 psi. If you want to go higher than that, we also have 7 bar MAP sensors.

Todd

I got Mopar Stage 3 on my car, so the MAP sensor should be 3 bar, that's why I thought it was weird not to get the good reading.

*EDIT*: Okay, I just read that it is caused by the PCM -> OBD2 port -> gauge communication. I suppose that I could splice the output wire from the S3 MAP sensor and plug it to one of the analog inputs of the gauge. Anyway, I'll get a 30 psi gauge soon, so that won't be an issue anymore. Thanks forcefedjunkie!