Apexi PFC and Boost Controller reading different boost levels?

[Kash_]

Hi guys,

Just a quick question, I noticed that my Apexi PFC has a different boost reading then my boost controller and boost gauge, usually PFC is lower. Which one of these should I use to find out the REAL boost reading?

Thanks :wave

[ro284]

Hi Kash,
 mines the same,  my  main mod is Efini Y pipe, and intake, with the standard ecu the boost flies up yo over 1 ba on the gauge, since i fitted the Y pipe, after fitting the Apexi the maximum is 0.84 which i guess relates to the settings on the commander, mines yet to be mapped, guess it\'s all in the settings which i hesitate to start altering them,
Bob

[BlitzBoy]

the setting you see on the commader is what the MAP sensor sees, I tend to find my MAP sensor reads lower then my boost controller and my boost controller read lower then my gauge, work that one out

[Kash_]

lol.... so which one is the more true reading out of the three?

[BlitzBoy]

haha who knows lol, the more expensive the Gauge or measuring equipment the better, well I will find out which is the more accrate when the car goes on the dyno as they plug in to get a boost reading so will go by their reading

[Carl]

The most likely reason for the different readings is simple.
They are measuring the boost in different places.
The ecu detects boost after the intercooler in the map sensor,which has a feed from the plenum,and the boost controller is likely to be setup to detect boost before the intercooler.
Before the intercooler the boost will be higher.
The engine sees the lower of the 2 boost pressures,so in reality is actually running that boost.
The intercooler creates a pressure drop on any car.
Alot of people think they are running higher boost than the engine is actually seeing,often 1.2 bar pre intercooler can be only 0.9 bar at the engine.
Regards
Carl

[BlitzBoy]

my feed for my gauge and controller takes a feed of the Plenum in my setup

[Grizzly]

It would be intresting to hook eack one upto say a Mitivac and see if they are all acurate, i know i had a Boost gauge a few years ago that was nearly 2 psi out (but that was in the Ford Days:2Rolleyes so it needed all the help it could get to look good)