R33 Gtst Boost Issues 0.5 Bar Cut

[Travis Trayhern]

Having a few issues with the the car when on the road in any gear if it hits .5 bar the engine cuts very smooth cut, no struggling no missing just bam that it nothing. untill your fully off the accelerator then it comes back to life, you can have the throttle 3/4 open and will rev to limiter.

history of things i have tried,

removed all turbo side replaced all gaskets lines that looked bad and clamps.

replaced TPS and AFM

removed factory boost solinoid and run manifold pressure to wastgate

removed all cooler piping and replaced some clamps all ok

changed plugs gap .8

running out of ideas?

[Travis Trayhern]

r33 gtst ser1

bought the car with this issue

[scotty nm35]

It sounds like some kind of boost cut, are you running the stock ecu or is it tuned? What gauge are you using to test the boost pressure?

[Travis Trayhern]

stock ecu on it, have an apexi boost gauge i have just connected for testing. makes boost ok but at about 6k its creeps up slowly from .45 bar and when it hits the .5 it cuts.

That was my first thoughts it was hitting the boost cut but my understanding thats at 1.2bar?

[Travis Trayhern]

any implications having the factory boost solinoid totaly removed?

[Sinista32]

.5 bar is 7.25 psi - whats stock on a 33 Series 1 ?

I thought it WAS 7 PSI

1.2 is 17 PSI - doubt that is stock

Has this got a restrictor that can be removed to get to 10+ PSI ?

[GTSBoy]

There is no "boost cut" on Nissan ECUs (alright, on the Neo, which actually has a MAP sensor connected to the ECU, there is a boost cut). But certainly not a boost cut on R33 ECUs.

What you DO have is a load based cut. When the ECU calculates a TP value (based pretty much just on AFM reading) which is too high, you get a cut. This can actually happen at a whole different range of boost levels, depending on how much other modification the car has (exhaust, bigger cooler, etc) and the weather, etc.

What I would suspect is that the boost gauge you are using might not be accurate, and somehow you have more boost than you think you do. Consider this one unlikely. Or you have a big boost leak that you haven't found, leading to high air flow at the correct boost in plenum. Or you have a faulty AFM.

[Travis Trayhern]

Ok changed a few bits has made it abit better.

Timing was set on 0deg so set cas to 15deg.

Factory boost gauge sensor was missing so grabbed one of another wreak out back now factory cluster works only goes halfway up won't go to the 7, which should be correct for 7psi.

Have connected factory boost solinoid.

Seems to get to 6500rpm now then cut.

Can't be afm as I have changed that.

But have noticed there is a beep from the ecu when it hits the cut?

[GTSBoy]

R33 rev limit is 6500? I know on R34 it is variously 6300 - 6500.

[Moodles2]

The stock cluster isn't in PSI, it's in mmHg. +7 mmHg is approx 13.2psi.

[GTSBoy]

The stock cluster isn't in PSI, it's in mmHg. +7 mmHg is approx 13.2psi.

Yuh, but I think what he was saying is that it only goes halfway up to the 7 (which is actually 700, not just 7), and that therefore he has about 7 psi.

[Travis Trayhern]

limiter is at 7200

And I know the factory gauge 7 on it is about 14psi that what I said it only goes to half which would mean its running 7pis = .5 bar or there abouts.