For the record i have an up pipe, and a full turbo back exhaust.

I just installed a MBC and went out to tune it. Upped the boost untill i went a little too far and hit 19.2psi Thing is my fuel cut never came on.

1-By disconnecting my factory boost solenoid did i eliminate fuel cut or does that come from somwhere else?

2-If not maybe my boost guage is reading wrong? Before the MBC i had hit an indicated 15.5psi which seems a little high for stock to me. My boost guage is hooked up to the output side of the turbo, should i move it to the intake manifold or somewhere else?

Thanks for any help

 

I hope you don't blow up your car....MBC's and the '04 ECU don't get along well....I think you may have just found out one of the reasons.
Get a reflash and be happy...keep using the MBC and you may blow your motor real quick.

Your boost gauge should be tapped off the by-pass valve vacum line.

 

19.2psi for a second is no big deal. it's a one-time spike and i seriously doubt the charge was hot enough to cause any detonation and/or engine damage.

fuel cut needs the pressure to remain above the threshold for some period of time... longer than your boost spike lasted. thus no fuel cut and no cel.

this is to avoid uncessary f/c and cels from boost spikes!

the f/c is initiated by the ecu and is dependent on a) the MAP sensor and b) some finite amount of time to pass above the threshold. the factory BCS does not need to be plumbed in for it to occur.

with the boost gauge there you are measuring compressor output pressure, NOT manifold pressure. you want to know manifold pressure, since a) this is the pressure of the charge entering your cylinders, and b) this is pressure read by the MAP sensor.

the boost indicated at your tapping point will be higher than that in the manifold. how much higher depends on total airflow. high airflow volume = high pressure drop from compressor to manifold.

as scotty said, a common place to tap in for a boost gauge is the BPV line, which is a manifold pressure source.

incidentally, does your boost gauge ever show vacuum?

hth
ken

 

ride5000
thank you for clearing up my questions, i'll move my boost guage line to the point you suggested.
and no, im not getting a vacuum reading