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Rb25 Greddy Profec B Spec Ii

PANGES

By PANGES,
in Engines & Forced Induction

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PANGES Apprentice

PANGES

Posted
Posted

Well.. I wired and hooked everything up today... but for some reason, when i set it at 10 psi and floor it, my car would jump up to 10 psi for a split second, then drop off down to 5psi, then go up to 8psi, then down to 5psi, then back up to 8psi and it just keeps jumping back and forth... did I install something wrong or set the BC wrong? I tried every gain setting for 10 psi and it still ran like that each time... Anyone have a profec b with their RB and have this problem??? It almost seems like it gets up there at 10psi but then something opens or leaks or something and my boost goes away...

I tried all the different gain percentages (from 3% all the way up to 35%) and it still runs the same... Also, is there a reason why I can only go between 5% and 35%? I hear people put theirs at like 0% and stuff... I have an R34 RB25DET GT-T engine in my 240sx if that helps any...

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BHDave Grand Master

BHDave

Posted
Posted

Check what the boost cut is set at as a start and whether or not there is a duty reduction that is tripped when you hit the boost cut. It is probably worthwile to increase the boost cut well above the 10psi you want to run as a trial.

PANGES Apprentice

PANGES

Posted
  • Author
Posted
You could be bringing the turbo on too quick and its having a megga fit.

What are your settings on the profect?

Gain, set, & SetGain?

gain- 28

set- 100 (psi)

setgain- 42

with thesesettings, it boost to 10, then drops to 5, then up to 10 again and it stays ther... When i shift, the boost drops down to 5psi and then goes back up to 10 fairly slow and stays at 10

PANGES Apprentice

PANGES

Posted
  • Author
Posted (edited)

I now have:

Gain: 21%

Set: 70

SetGain: 49%

These settings gave me a very nice 10 PSI pull last night. It was boosting perfect last night. Holding very smooth and pulling hard. However, today when I drove around wtih the same settings, It spiked to 11.3 PSI and then it would bounce around between 9 psi and 11psi.... any thoughts?????

Thanks

Edited by PANGES
RedDrifter Experienced

RedDrifter

Posted
Posted

Ok this should help get rid of any confusion.

Set:- This is the max duty cycle the solenoid will run.

Think of it as how much air it will bleed off.

e.g. 20% will bleed of approx 20% of the pressureised air.

Gain:- This is how fast the boost controller will allow the solinoid to go from o% duty to the set duty cycle. This seting will bring the turbo on faster or slower etc.

SetGain:- The boost controller will bleed 100% air off till the set pressure and then just run the setting of set and gain (1st 2 points).

Ok The best way to set up the controller is to turn setgain to zero to start with.

Then adjust the set to your desired level of duty cycle. 20% should add approx 20% more boost than the set spring on your waste gate actuator.

Now start at 35% gain and go for a blat in third (on the highway). No all you need to do is keep dropping the gain till the boost stats to spike and back it off a little.

(too lower gain setting and the boost will spike, Too higher gain and the boost will come on to slow and/not reach the correct boost level.)

Once you get your boost comming on hard and staying constant just increase the setgain now untill it starts to spike and then just back it off.

Hope this helps and good luck.

Oh yeah, Also make sure your stock boost control solenoid is disconnected from the system.

V8eta Apprentice

V8eta

Posted
Posted

I have a Profec B spec 2 on my rb20det using a vg30 turbo with an rb20 actuator.

I have the gain set at 2% at the moment and the start gain setting at 0.87bar, this gives me a nice setting with minmal spike, holds around 1.15-1.2 bar like this.

From the experience i have had with the controller the less gain set the better.

RedDrifter Experienced

RedDrifter

Posted
Posted
What settings are your running on yours? just curious. I'm going to play with it tonight.

For 16PSI (Lowboost)

Set-->65

Gain-->19

SetGain--> 0

For 20psi (High Boost)

Set--> 75

Gain--> 12

SetGain--> 0

On a cold night you may need to increase the gain.

On a hot night you may need to decrese the gain.

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