Jump to content
SAU Community

Recommended Posts

Hey guys,

Started my car today and realised the (HI) symbol on the top left corner of my profec b was flashing.

Thought this was unusual as that normals stays permanently on, it does not flash,

I then go into (LO) mode and that's doing the same thing too, flashes constantly...

Even tried turning the unit Off and back on, still the same thing

Can anyone help me? Why all of a sudden the hi and lo symbols started flashing?

Link to comment
https://www.sau.com.au/forums/topic/357598-greddy-profec-b-spec-2/
Share on other sites

yeah i've had 4 or so in various cars of mine and never had a real problem with one. I found on GTRs with small twins that ramp up really hard onto boost they can't bypass enough air immediately and get a tiny spike but apart from that they are great. spike only lasts for a 10th of a second if that so it's not really an issue. when set up right they hold very stable boost.

alil off topic, but the 2 hoses that go from the wastegates then into a t-section that join to the boost control solenoid, is it recommended that both wastegates hoses be of equal length? my solenoid is mounted under the air pods, so naturaly the front turbos wastegate hose is shorter then the rear

would having equal length hoses make a difference in say holding/controlling boost/spool time etc?

cheers for the replys

close to equal is a good idea. doesn't have to be exactly perfect but if there is a big difference it can have an effect. overall you want the lines as short as possible. unfortunately most people re-use the factor GTR set-up which has the solenoid a LONG way from the turbos (usually mounted on driver side near strut tower). mainly because it's easy to put there with the factory vacuum hoses and it's easy to get the wiring through the bung there into the cabin.

Yea i browsed through the manual and didnt see anything

I had my solenoid by the brake booster and used to get a little spike on gear changes so i relocated it to the passenger side by the strut tower and made all the lines as short as possible with equal lenghts to the actuators etc.etc. and did get a decrease in spike

As baron said with the quick ramp into boost a small spike is almost inevitable but they hold boost pretty good otherwise

One other thing i have to try is taking the pressure source from the twin turbo pipe but just hasnt gotten around to drilling and tapping it to take a nipple.....

in my new car (32 GTR with jun 2.7, 230s, cams, motec) it has a profec b II that was set-up in japan. one interesting thing about this one is the profec B II is set-up with no 'start boost' setting. it just has the % number in (gives the boost level) and the gain number. surprisingly it still ramps up super hard. personally I always use the start boost to get the thing spooled up to near the target boost as quick as possible but it seems to work fine as is.

if you are having a play with yours try setting the start boost down to zero and see how it performs. it may cure any spiking problem and in my experience doesn't really increase lag at all.

with mine running at 18psi i have the start boost on 125 (12.5) and only seems to spike very little. some people say to run the start boost as close as the boost presure ur running or usualy around 3 or so psi less. mine spiked when the start was that close.

interesting to hear ur start boost was on zero? then again maybe running a 2.7L has something to do with it still been able to boost hard and quick?

in my new car (32 GTR with jun 2.7, 230s, cams, motec) it has a profec b II that was set-up in japan. one interesting thing about this one is the profec B II is set-up with no 'start boost' setting. it just has the % number in (gives the boost level) and the gain number. surprisingly it still ramps up super hard. personally I always use the start boost to get the thing spooled up to near the target boost as quick as possible but it seems to work fine as is.

if you are having a play with yours try setting the start boost down to zero and see how it performs. it may cure any spiking problem and in my experience doesn't really increase lag at all.

Yea i'm sure engine mods/displacement had alot to do with that plus i assume its 2530s with the upgraded hks actuators?

I guess i use the same method as you as I have my start boost just a few psi lower than the target boost and gain all the way down to lessen the spike but the spike is very small and quick so it doesnt bother me to tell you the truth and boost creeps just a few points of a psi as rpm increases

I'll experiment with that setting you mentioned above tho as i dont think i ever tried it that way and its been a while since i even touched that controller

yeah sirRB, you're right, it's not always possible to have the start boost that close to target boost without spiking. especially with stock, or small twins like GTSS etc. mine would spike if i had start boost too close. it's just a matter of adjusting it down a bit or lowering the gain helps too.

yeah the 2.7 definitely makes it torqier off boost and yes it does have 2530s with HKS actuators (not sure what pressure they are set to). it may be that they set the actuators to crack at like 1 or 1.2 bar so there's no need for the start boost setting.

  • 1 month later...

So the "set gain" basically tells the actuators when to start opening? So the longer you can keep them shut, the harder the car will come onto boost?

But possible spiking may result if too close ?

I didn't know running a high gain will cause spikes too, I'm currently (with the cold weather) getting massive spikes when giving it full stick ! I tried lowering the set gain even down to 10 and even 5 but didn't get rid of the problem completely...will have to turn the gain down afew notches and see it goes

In regards to the flashing if its similar to the blitz its means its in edit mode and you can alter the settings if its not flashing means its in set mode. Personally I dont like playing with the boost controller myself and mucking around with the settings as its hard to get WOT in 4th on the road to test out what its going to boost to and if it spikes like you can on a dyno so I like to keep it as it is when it was tuned.

So the "set gain" basically tells the actuators when to start opening? So the longer you can keep them shut, the harder the car will come onto boost?

But possible spiking may result if too close ?

I didn't know running a high gain will cause spikes too, I'm currently (with the cold weather) getting massive spikes when giving it full stick ! I tried lowering the set gain even down to 10 and even 5 but didn't get rid of the problem completely...will have to turn the gain down afew notches and see it goes

exactly mate. the set gain is set so that the controller will keep the wastegates shut up till the set gain point is reached, then it will start bleeding air to smoothly reach your target boost. if set gain is too high there is not enough time for the controller to start bleeding off air and stop the boost curve climbing before it reaches (and goes past) your target boost level.

try setting set gain to zero. do a full throttle run. adjust the gain setting until you still have a nice fast boost climb but no spiking. once you've got that sorted then re-introduce the set gain. if your target is say 1bar you generally can't have set gain any higher than about .7bar or so.

Cheers beer baron.

Target boost is 18ish psi with -7's

So far seems to be good, holding boost and not getting big spikes

Boost% 50%

gain 17

Set gain 125 (12.5psi)

Drops about one psi at high rpm, 6000rpm +

not bad so far.

Also wen u say put ur set gain to 0, wouldn't that mean max boost would come late and more smoother?

yeah 1psi drop across the rev range from 18 to 17psi is pretty good.

yeah theoretically setting set gain to 0 means no pressure keeping the gates closed. didn't make much difference on my car as it has HKS actuators that hold closed a lot longer than stock anyway.

ok had a run on the dyno yeterday @ V&E Rigoli dyno day...boost hit 19.5psi then tapers off to about 17.8psi by redline

so still not holding steady boost, its still dropping almost 2% ish, is this normal behavour for a profec b controlling 2 small turbos?

if i turn the Gain up further, i get mad boost spikes...

gain is at 17%

start boost is at 90 (9 psi)

Edited by SiR_RB

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
×
×
  • Create New...