Mitsubishi Lancer Evolution Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
6,345 Posts
Discussion Starter #1 (Edited)
Hi guys,

Got myself GFB Deceptor Bov - the older version, and overall it's great - recovers boost quickly, can be adjusted as needed, etc.

My only problem is in certain driving conditions it doesn't open and causes the following:

Let's assume the following accelerator pedal input in 4th or 5th gear. BOV is adjusted to softest possible setting.

Scenario 1: Stumbling and Violent Shaking
t = 0
Accelerator Input: 40%
Boost: 1 PSI

t = 1 second
Accelerator Input: smoothly down to 20% over 1 second period
Boost: unknown, but definitely not -21 inHg
CONDITION HERE: Car is shaking and stumbling violently as if it's just lost 2 cylinders. Very lean condition and BOV does not vent.

Scenario 2: Proper Operation
t = 0
Accelerator Input: 40%
Boost: 1 PSI

t = 1 second
Accelerator Input: abrupt drop to 0%
Boost: -21 inHg
All smooth - BOV opens and vents as expected.

I suspect that during the surge, MAF is being hit with reverse or stopped airflow and this screws up the fuel injection routine. Since I am at 20% throttle still however, all this mess is translated into car buckling, sputtering and shaking violently until turbo surge goes away.

Similar CAN be replicated with stock BOV but only in 5th gear in dangerously low RPM uphill, which is not a problem since if one is doing this, it's bad to begin with.

With GFB however, I have this in 4th and 5th and it's quite anoying when you try to drive smoothly without dropping throttle after every somewhat sizable speed adjustment.

You know I want to go 20% -> 40% -> 20% throttle... but what I get is 20% -> 40% -> ^[email protected]#&^*&^^&@ -> 20%.

Obvious issue - not enough vacuum from the engine to open the BOV, but what is a solution? Larger vacuum line? Different BOV placement? I am using stock vacuum line that connects to stock location.
 

·
Registered
Joined
·
6,345 Posts
Discussion Starter #2
From GFB website:
Another very important reason for having a diverter valve is for the benefit of the engine management system. Compressor surge in modern cars can have the potential to cause drivability issues such as jerking or “bucking” during a partial throttle lift, most commonly affected cars are late-model Mitsubishi EVOs. Whilst the factory valve is designed to eliminate this issue, it also prevents higher boost pressures being used and doesn’t offer the maximum possible throttle response, opening the door for a well designed aftermarket diverter valve.


But it's on softest set up right now... or am I doing something wrong here?
 

·
Registered
Joined
·
6,345 Posts
Discussion Starter #3
Bump
 

·
Registered
Joined
·
57 Posts
Did you get anywhere with this? I’m running into a similar issue.
 
1 - 4 of 4 Posts
Top