Profec B Spec2 On Rb26

[Don Dada]

Hey guys.

Recently installed a ProfecB spec2 on the 26 and no matter how i tune it i cant get rid of the spiking.

I took the pressure source from the original nipple at the back of the plenum, to the solenoid mounted by the brake booster, and then to the solid line that goes around the back of the engine to the actuators. This was the shortest possible run i could of gotten.

The source for the unit is taken from the nipple that goes to the oem boost gauge.

If seen a few ppl still get spike using the same said controller on the 26.

My question is.....

Has anyone tried taking a pressure source from the pipe that comes directly off the turbos and mounting the solenoid on the turbo side of the engine thus keeping the run of the hoses as short as possible?!?

My settings are:

LO boost- 12 psi

Gain- 5% (lowest)

Start Gain -8 psi

Warning - 14 psi

Limiter - 15%

HI boost- 14 psi

Gain -5% (lowest)

Start Gain - 9 psi

Warning - 15psi

Limiter - 15%

Stock turbos, 3" no cat exhaust.

As u can see the gain is on the lowest setting, and even though i turn down the "Start boost" setting it still spikes, so i dont think there is anything i can do again in terms of tuning the controller.

Thanks.

[bubba]

Is it actually spiking? (if so, to what?)

Or, is the boost falling off?

What does it do with no % increase?

[Don Dada]

on low boost set at 12ish psi it would spike to about 13-13.5 psi on gear changes

on high boost set at 14ish psi it would spike to about 15-15.5 psi on gear changes

Boost does not fall off

With no % increase, wouldn't this be the same as if the controller was off?

If so it runs 8-9psi with verrry little spiking

[Don Dada]

Do u guys with other other brands of EBC (HKS,Blitz,Apexi etc.) experience this same problem?

It holds boost fairly constant, it's just the spiking on gear changes i'd like to iron out.

[zebra]

what do you mean spiking on gear changes? Like when you snap the throttle shut it spikes?? that happens because the turbos are going flat out and when you close the throttle plates the boost backs up. No BOV is going to be able to expell that much air instantly, hence the small spike

[MrStabby]

what do you mean spiking on gear changes? Like when you snap the throttle shut it spikes?? that happens because the turbos are going flat out and when you close the throttle plates the boost backs up. No BOV is going to be able to expell that much air instantly, hence the small spike

+1. Fast moving air has a lot of momentum. Also remember that the boost will spike on the turbo side of the throttle, not the engine side so the engine wont see it and you have no problem. If it spikes in gear then different story.

[Don Dada]

When i change the gear and stamp the throttle open, it goes up over the preset boost value for a second, and then drops back to where it supposed to be.

[zebra]

There will be no pressure in the actuator lines to open the wastegates,

So as you suggested, try making the lines as short as possible and try not to have any other things running off those line, i.e boost gauge, pressure reg etc

Edit - Also try disconecting the factory boost guage line and run just the line to solenoid / wastegates as it maybe leaking

[KR4-GTR]

I just bought one of these but havent installed it yet.

Does anyone else have the same problem as 'smell'? its the first i have heard of it?

[bubba]

When i change the gear and stamp the throttle open, it goes up over the preset boost value for a second, and then drops back to where it supposed to be.

Sounds like your SETGAIN value is too high, what's it like rolling on in gear?

[GT-RZ]

Bigger and better flowing wastegate is the best way to fix this.

With an actuator it gradually begins to open up and is fully open when boost has hit the actuators rated pressure. Problem with this is that you loose pressure inside the turbine which leads to slower spool up and less response.

All a EBC does is control a one way pneumatic pressure valve (mechanical ones work fine too ). This way you set the pressure for the valve to open not the actuator (must obviously be >=as the actuator pressure). When the pressure reaches the valves release threshold it flies open instantly and immediately opens the wastegate when it hits the actuator.

If the wastegate is too small/crap flow there is the potential for the turbo to not rid enough gas quick enough and a short spike in boost as it all tries to run through the same door.

True fix is a larger more flowing wastegate. easy. but really 1-1.5psi spike is nothing i wouldn't worry about it.

That being said as others have mentioned it is also important that there is no restriction/loss of pressure to the actuator.

[bubba]

Guys, by the sounds of it it doesn't happen with the ebc turned off so I don't think it has anything to do with the mechanical setup.

To me, it sounds like poor ebc setup.

I run two of these ebc's with no dramas but if they aren't set up correctly then it can be very discouraging.

Basically, you use the SETGAIN value to bring the boost on earlier. Each individual (mechanical) setup will determine how close you can have your SETGAIN value to your SET value (target boost). For example, my skyline with underturbo'd RB30DET (25 turbo so comes on boost really hard and fast) has a fair difference between the SET and SETGAIN values. My stagea with a stock neo engine and hiflow'd turbo is much lazier coming on boost so I am able to bring the SETGAIN value up closer to the SET value.

Read the manual, the GAIN value can be used to smooth out spiking OR tapering.

First step, is back off the SETGAIN value (even back it off completely) and see if it still spikes after changes.

[Don Dada]

Like i said in my first post, gain is set to its LOWEST. and even with the set gain(start gain) set at 0 psi also, it still spikes.

[bubba]

Like I said in my previous post, the GAIN setting can be used to fix boost SPIKES or tapering. Read the bloody manual.

Start by increasing the GAIN 2 points at a time until instead of "spiking" it goes to that boost level and holds there (reduce your SET value some as both SET and GAIN affect overall boost).

What you will effectively be doing is using the GAIN function to bring the boost curve up level with the spike so it is no longer a "spike".

I don't know how much clearer I can make it.

[Beer Baron]

i've had great success with the profec B IIs. I've had a few of them. ran one on my old GTR set-up 5 years ago and it was good, ran one on the GTR I had built in japan with HKS turbos, cams, built motor etc. and it worked well too. and am running one on the new set-up too. in fact it seemed to work better than the profec E-01 in my silvia which was $1000 when new!

this is the kind of boost curve you should be aiming for.

[Don Dada]

Quote from the manual...

"When boost spike occurs,lower the GAIN adjustment 2 increments at a time until it stabilizes."

and

"Adjusting the START BOOST too close to the SET boost pressure,it will cause boost spike"

So yes i can read AND follow instructions

Don't know which part in the manual u saw to raise gain 2 points at a time to get rid of spike

[Don Dada]

i've had great success with the profec B IIs. I've had a few of them. ran one on my old GTR set-up 5 years ago and it was good, ran one on the GTR I had built in japan with HKS turbos, cams, built motor etc. and it worked well too. and am running one on the new set-up too. in fact it seemed to work better than the profec E-01 in my silvia which was $1000 when new!

this is the kind of boost curve you should be aiming for.

I remember reading some where u too also had some spiking on gear changes?!?

Curve looks sweet, but that is from low rpm in 4th i assume? If i do the same on the street i do not get any spike.... only on high rpm gear changes other wise it's smooth to redline.

[bubba]

Can't be bothered with people that don't bother to read. Good luck.

Edited July 14, 2009 by bubba

[Beer Baron]

with small turbos that ramp onto boost very hard you will occasionally have trouble controlling them as they ramp up. if you are at boost producing rpm. say 4500. at part throttle. and you stamp on it. they turbos spool up to target boost faster than the solenoid can bypass enough air to stabilise the wastegate. it should not be a big spike but yes you can get a small spike under conditions like that. it's not a big deal if it's only 1psi or so which is all it should be. you really need to replicate it on the dyno with proper logging of the boost curve. as sometimes the controller might beep or display a high peak that it's hitting for a nano-second as it swings into action to stabilise your boost. it can be such a brief occurrence that it's not worth worrying about.

[RBwhatever]

with small turbos that ramp onto boost very hard you will occasionally have trouble controlling them as they ramp up. if you are at boost producing rpm. say 4500. at part throttle. and you stamp on it. they turbos spool up to target boost faster than the solenoid can bypass enough air to stabilise the wastegate. it should not be a big spike but yes you can get a small spike under conditions like that. it's not a big deal if it's only 1psi or so which is all it should be. you really need to replicate it on the dyno with proper logging of the boost curve. as sometimes the controller might beep or display a high peak that it's hitting for a nano-second as it swings into action to stabilise your boost. it can be such a brief occurrence that it's not worth worrying about.

This exactly what mine does also.

Stamp on the throttle through the gears and it'll spike up to 2.5psi over the set value as it quickly boosts up, but its there for like a half second then it drops back and holds perfect.

Slowly boost up under load in a higher gear and it holds boost dead still with out spikes.

As far as I can see it's exactly a beer baron explained and nothing to worry about.