i have a hallman pro rx mbc. i just got the car retuned and set the MBC to 21psi. 1st - 4th gear hit 21psi at most. the weird part is, in 5th gear, the boost goes past 23-24psi

is this a sign of a faulty mbc?

 

I think it's normal.
Higher gear means more load= higher boost.
If you're tuned, I wouldnt worry too much.
My car does the same thing.

 

thats weird - im running on 91 and cant afford hitting 23-24 psi. does this mean im gonna have to turn down the boost till it hits 21 psi max for 5th, and run alot lower in all the other gears?

 

Yup! Your max boost overall is your max boost reading in top gear. What year Evo do you drive? What are all of your mods? Do you have a stock turbo, with an unported 9.8 or 10.5 HS? If your hotside(turbine housing) is unported, then you may be experiencing boost creep caused by insufficient exhaust gas volume being bled off via the too small wastegate bypass port.

 

Best thing to do is call the shop that tuned your evo.

I had mine done at AMS and was told it is safe but I am running 93oct.

 

i have an 03 evo with a high flow cat, cat back, downpipe, k&n filter, o2 housing, dual port 10.5 hotside.

the tune was specifically for the addition of the o2 housing and hotside. had a walbro fuel pump installed too recently

before the hotside / o2 housing, i had an old tune that would hit 19 psi max in every gear.

i called the shop and the guys were saying it was the MBC. they dont trust the hallmans though because they've seen a couple customers have faulty ones while tryin to tune them..

is there anythin to change to fix this? or is it really normal and just back off on the boost?

 

I just recently installed the hallman to replace my forge. I like the forge much better. It definately was more consistant and held boost better on my car. My hallman spikes quickly to 22psi, sits at 20psi from 4000rpm to 5600rpm , then tapers off to 17psi by redline. If your hitting 21psi in 1st gear, you probably need to turn down the boost.

 

Higher boost in higher gears or higher loads is completely normal.

My boost climbs a bit in 4th and 5th. It still falls off up top but midrange does grow to 23psi at times.