Some Tuning Problems

[checkmate!!!]

Hi guys,

I'm in need of some advice and help.

I have a 32 GTR which had the following mods:

Kakimoto GT1 OZ Racing Exhaust

Vortex front pipe

R34 N1 Turbos

Apexi Hybrid Intercooler

Forged Pistons

Nitto Oil Pump

Tomei Cam Gears (dialled in, cant remember though)

Some Japanese chipped ECU

boost tap (like a boost tee)

When these mods were on, the car made about 260kw on the rears.

It would peak at 20psi and taper off to 18psi.

I had it dynoed at at different tuners about 4 months later and it put out 235kw ( this is not the main point though)

These were both on Dyno Dynamics Dynos.

However about 3 months later, one of the intercooler pipes started to leak and hence I did these mods to it:

JJR hard pipe kit

Z32 AFM

Blitz Dual Solenoid Boost controller

Sard 700cc injectors

New NGK iridium spark plugs (correct gapping and stuff)

Tomei Type A camshafts

NISTUNE ECU

When it was getting tuned, the stock BOV's couldn't take anymore than 15psi and as a result was forced to use 2 HKS SSQV's i had lying around.

The power curve was like a wave up top. The BOV would just open, close, open ,close until red line.

The SSQV's didnt fair any better and only held 16psi. with the same waving problem.

This time it was tuned on a Mainline Dyno and pulled 260kw on the SSQVs.

I am however very annoyed at those BOVs and want to go back to stock ones.

However cannot understand why the stock BOVs handled 20 psi if not 18psi with no problems on the previous setup but cannot handle the boost now.

I plan on upgrading the puel pump next, but i dont want to take it to the tuners, pay for it and get the same result.

I want to break 300kw and im very confident that it should, with an upgraded puel pump.

Right now the car doesn't feel as alive as it did when it had less mods.

Any ideas?

Thanks in advance for help.

Edited March 27, 2012 by checkmate!!!

[R.3.2.G.T.R]

try blanking the bovs off and try again to see if it holds up top

[JonnoHR31]

Stupid question, but were the BOV's vac lines hooked up properly?

[checkmate!!!]

Hi,

Stupid question, but were the BOV's vac lines hooked up properly?

The vac were prettly much all re-done.

try blanking the bovs off and try again to see if it holds up top

I thought that blockiong the BOVs completly would destroy the turbos very quickly. In which, I don't really wanna travel down this path.

Thank you for the suggestion though.

[GTSBoy]

Well, it won't. So try it.

[DVS JEZ]

If its the saw tooth up the top, alot of GTR's have had this issue, is it a 4wd dyno?

Is it only the power graph that does it or can u see the boost line oscillate up and down?

Please post up ur dyno sheet with boost graph.

Have u tried running it on the dyno in 2wdrive?

[checkmate!!!]

The Dyno is a 2WD one.

Did what most people would with a 32 and just pulled out the fuse in the engine bay.

[DVS JEZ]

The boost is oscillating which is normally caused by too much gain in the boost controller

[Brezza]

The boost is oscillating which is normally caused by too much gain in the boost controller

byt gain, do you mean sensitivity setting or the gate pressure setting?

on my boost controller there are 3 things that you set for each boost level.

Set Point, Gate Pressure & Sensitivity

my car has the problem of oscilating boost at 24psi. but at 20psi it is fine.

we tried turning sensitivity right down and it still doesnt help.

the only thing i noticed were different were the gate pressure settings, for each settings were that the gate pressure is different

on one it is 0.8 (24psi setting) and the other is 0.5 (20psi setting)

i think these measurements are in BAR so 0.8 would be 11.6psi and 0.5 would be 7.25

the actuator is a 14 or 15psi actuator.

here is my dyno graph.

Dyno Results - (360rwkw) @ 20psi (Power vs Boost).pdf

Boost Controller Instructions.docx

[R.3.2.G.T.R]

did u get this sorted, perhaps the different gate pressure up high is leading to the oscillation, how did u check this, with air comp?

[FordyR31]

If it isnt sorted is there a way to check the springs or diaphrams in the actuators? May be a possibility thats over looked. If one or both aren't working properly could that be causing the boost to do what its doing?

[SargeRX8]

I don't think it has anything to do with the BOV's. I had the exact same problem with my old car. Boost would come on then flop then on then flop and you can hear it, the turbo sucking hard then backing off then sucking hard. Took it and shoved it on a dyno. It displayed pretty much what your boost plot shows, an oscillating line. In my car it was my boost controller setup incorrectly. It would come onto boost, hit the warning and because the warning(max boost) wasn't set right, it would open the gate and I would lose all pressure and turbine movement. It would then shut the actuator and do it all over again. Few moments of fiddling with the controller, we got a dead straight line. If you've got pod filters, you should be able to tell by the sound if it is your BOV's venting. If it just sounds like suction on, suction off, suction on, i'd say its your boost controller. Quick method to test it out is run actuator pressure and bypass the boost controller. If they don't hold enough boost to test properly, get a bleed valve and just set it up($25 just to set it out with) to what ever psi you want then see how it goes.

Its really unlikely to have failing GTR BOV's, let alone SSQV's doing the same thing. I run 19psi through a stock GTST BOV...

[STATUS]

too much gain not enough set or the boost cut on the sbc was set too low.