AEM Tru Boost Vacuum Line

[Phoenix_gts86]

Hey I have finished installing my Aem Tru Boost gauge into my Turbocharged 2013 Gts86, everything is connected, if it wasn’t the gauge would be showing Error.

I have tapped the vacuum line from the gauge into the brake booster and the gauge is reading double the amount of psi the car is running, my oft reads the correct amount and the gauge is reading double that amount. Where the oftv2 will read about 9/10, the gauge will read -18/-19

Where about can I tap the vacuum line from the boost gauge?I’ve attached the bov vacuum line into the 4 piece connector with the boost gauge.

Thanks a bunch!

[tomm.brz]

with oft you mean "boost" value?
boost value is a relative pressure measurement, on brake boost line is manifold absolute pressure, ergo boost + atmospheric pressure

[Fred E]

Originally Posted by Phoenix_gts86

Hey I have finished installing my Aem Tru Boost gauge into my Turbocharged 2013 Gts86, everything is connected, if it wasn’t the gauge would be showing Error.

I have tapped the vacuum line from the gauge into the brake booster and the gauge is reading double the amount of psi the car is running, my oft reads the correct amount and the gauge is reading double that amount. Where the oftv2 will read about 9/10, the gauge will read -18/-19

Where about can I tap the vacuum line from the boost gauge?I’ve attached the bov vacuum line into the 4 piece connector with the boost gauge.

Thanks a bunch!

This might be because the OFT is reading PSI when in vacuum, while the gauge is reading inHg. The conversion factor from PSI to inHg is 2.036 (i.e. inHg = PSI x 2.036). When you go into positive pressure, the gauge should switch to PSI automatically, and then back to inHg when in vacuum.

Edit: main point being that there is no concern with your routing and you can go enjoy the boost.

[Phoenix_gts86]

Originally Posted by tomm.brz

with oft you mean "boost" value?
boost value is a relative pressure measurement, on brake boost line is manifold absolute pressure, ergo boost + atmospheric pressure

Yeah with oft I meant boost value, I just would have thought it should be reading the same as the oft but then again the oft doesn’t have a vacuum line being tapped into the brake booster line

[Phoenix_gts86]

Originally Posted by Fred E

This might be because the OFT is reading PSI when in vacuum, while the gauge is reading inHg. The conversion factor from PSI to inHg is 2.036 (i.e. inHg = PSI x 2.036). When you go into positive pressure, the gauge should switch to PSI automatically, and then back to inHg when in vacuum.

Edit: main point being that there is no concern with your routing and you can go enjoy the boost.

Oh okay that’s something to learn from, as said in previous reply to Tom.brz “Yeah with oft I meant boost value, I just would have thought it should be reading the same as the oft but then again the oft doesn’t have a vacuum line being tapped into the brake booster line”

Looks weird when it’s -18/-19 then goes positive when hitting boost while the oft displays -10 and reaches positive boost “naturally”