Skylines Downunder NZ Car Club

General Automotive => General Skyline Discussion => Topic started by: Beached on October 29, 2018, 10:03:14 PM

Title: R34 GTT Boost Issues
Post by: Beached on October 29, 2018, 10:03:14 PM
OK so early this month I went to get my r34 tuned from a reputable tuner.
The tune was going well until we ran into a problem. We couldn't make anymore boost than what the wastegate actuator was set to (10psi).
We tested out a different EBC and still had the same problem so we thought that the problem was the wastegate actuator.
We tested a boost tap and got 22psi so we ruled out the actuator so we thought it was the boost solenoid valve.

The next day I bought a brand new mac 3 port boost valve and put tested it out on my car. I also raised the preload on my wastegate spring.
Drove down the street and got up to 18psi so I thought the problem was fixed and booked another date for my car at the tuners.
While I waited for my tune I turned my EBC off in hopes that I wouldn't over boost although I was still making upwards of 17PSI even though I was "never" using WOT.

Then I bring my car back to get tuned thinking that the problem had been fixed but on the first run its stuck on 11psi.
We tried changing relevant vac lines with new hoses.
We made sure that the new boost solenoid is operational.
We put pressure onto the internal gate via a compressor to make sure it wasn't flapping open prematurely.
But we couldn't figure it out so I ended up leaving gaining 1 pound of boost..

On the drive home I went to a long straight private road and in fourth gear with the EBC off I made 16psi @ 5500 rpm..

Any clue as to why my car wont make boost on the dyno but it will on the road?

My mods are as follows..
Pod Filter W/ 3" intake pipe
Highflowed OP6 Holset recore w/ R32 GTST 10PSI actuator
Deatchwerks 320lph Fuel Pump
Sard FPR
650CC FIC Injectors
Greddy PRofec B-spec II EBC
Splitfire coils
3" exhaust
Nistune type 4 daughter board

Any help would be much appreciated! next step will be changing the actuator to 18psi and removing the EBC..
Title: Re: R34 GTT Boost Issues
Post by: Looney_Head on November 02, 2018, 08:26:28 AM
what are your gain and duration set to, do you have pictures of how the lines are routed, and how its wired in?

its been many years since i have played with a profec b but i remember them being a pain to get working properly
Title: Re: R34 GTT Boost Issues
Post by: Beached on November 03, 2018, 11:32:58 AM
My tuner has the same EBC on his GTR and he has confirmed that it is wired correctly. We even replaced all of the silicon hoses with rubber hoses and ran them out of the bonnet and through the window (instead of through the firewall) to avoid crimping.
We tried countless settings on the EBC and nothing would change boost levels. We even tried another Greddy spec II EBC that we knew was working and still had the same problem.
My tuner is leaning towards an earthing issue so when I get some free time I'll go over all my earthing points to make sure they have a solid connection.

Thank you for your reply. Any help is hugely appreciated!
Title: Re: R34 GTT Boost Issues
Post by: Looney_Head on November 12, 2018, 08:34:48 AM
Hi, Did you get anywhere with this, i would have said it was either a check valve, lines or the boost controller being the issue
Title: Re: R34 GTT Boost Issues
Post by: Beached on November 20, 2018, 10:48:49 PM
The problem doesn't seem to exist unless it's on the dyno and I ended up buying a few more parts so I'll wait till they're on the car until I book my next dyno session.
I've cleaned up all the earthing points and added a couple more so if it was an earthing issue I'm hoping that it's gone.
I also found about 10meters of cable under my carpet that was for an old TV system which was still getting power and the earth was connected to the plastic dash..

I'm almost certain that it isn't a fault in the controller since we tried a different control unit, solenoid and new vacuum lines at different points in the intake manifold.

I've just had a v-band flange welded to my stock manifold and got a 38mm external gate so no room for failure next time! Although I do like having the option to use low boost.