Boost Problems

[Gold Rays]

Hi all,

At the moment I'm only running 8psi on my 95 S1 R33 and when I hit boost in 4th gear the boost spikes and the engine seems to cough and splatter.... its weird. It never used to happen before I put my hybrid front mount on and put a T piece in. Its not hitting the rev limiter, seems more like fuel cut or something, it couldn't be boost cut althou it does spike up to 14psi some times if I give it heaps. A list of what mods I've done are below. Any help or knowledge on how to fix the problem would be great.

Cheers

[jmp]

Not sure if it's related but with my Turbofart bleed valve I find that my boost spikes quite a bit on the higher gears (4-6th) on my S15..

May be the same thing and it's spiking enough to hit cut or something?

I'm interested to find out if it is or not .. ho hum

cheers, josh

[BOOSTD]

Could be plug gaps or boost cut.

Boost cut is a A/F versus time versus rpm calculation not boost level, which means It might not cut at a certain boost level all the time ,but, just when loaded up. Be carefull with fuel cut defenders as they are easily set to low causing lean mixtures and detenation. hope that helps

plug gap should be ~.7mm

[2BNVS]

yer it could be fuel cut out, i was having the same problem at bout 4500-5000 rpm... but mainly when i gave it in 3rd gear...

ben...

[muffas 180]

There is no such thing as boost cut. It is fuel cut. Standard ecu dont read boost pressures. They read the mass of air traveling through the AFM.

As BOOSTD said it is probably plug gaps. RB25DET's are very sensitive to plug gaps being bigger than .8mm when running more than standard boost levels. I recommend .7mm too.

Michael..

[Gold Rays]

Cheers guys

So what plugs do you recomend? I already have NGK platnum plugs but I'm not to sure of the gap.

I thought the GTSTs ran rich so even if u wind the boost up a little eg to 12psi, the engine shouldn't detonate.

I think it could be the crap turboX bleed valve causing most of the problems... Its could be time for an AVC-R

[nitemare5]

Sounds to me like fuel cut from what you have described, though is from personal experience in a mates r33.

[GTR-80Y]

Turn down the boost or get a better boost controller. Happens to me sumtimes on a cold nite in 4th gear. Higher A/f in 4th according to the safc so should be boost cut as stated by boostd.

[muffas 180]

What is boost cut? Is this where the computer stops the turbo boosting?

Or does it cut fuel delivery to the eng.

Michael...

[BOOSTD]

What is boost cut? Is this where the computer stops the turbo boosting?

Or does it cut fuel delivery to the eng.

Michael...

Shuts the injectors down.

[RbHed]

could b d i/c piping... maybe loose

look around n just tighten everything up