R32 Gtr Not Making Full Boost, And Feels Very Sluggish

[black sky]

Hi People's

There's something wrong with my car. At the moment what happens is that when i put my foot down it gets up to about 5 psi fine and then just seems to stay there or even drop a little when it's on standard boost which is 7psi. When i put it on high boost which is 1 bar. It gets up to about 9 pound and is then very erratic and it's go up and then down a bit some times it rev's out and fine but feels very slow and other times up the top of the rev range it stutters a fair bit. when i turn the boost off it makes about 5-6 psi but the car just does not move. It revs out but just feels very very slow. When i give it rev's and drop the clutch (rear wheel drive) as soon as it hit's boost it just stutters). i looked at the power FC and everything looks fine and the injector duty cycle seems fine i can't see any leaks. and it ramps onto boost fine. All the interior guages seem fine. I have a metal cat but my car is just a street car could it be melted???

This Problem happened last night. I had it on high boost and was flooring it when at about 6000rpm it seemed to loose power and that problem has persisted to now.

The car's modified it has:

ACL Forged Pistons

ACL Piston Rings

ACL Big End Bearings

ACL Main Bearings

Ported and polished head

Stock polished crank and rods

Bored and honed Block

N1 Oil pump

N1 Water pump

Tomei Oil Gallery restrictor

Gates timing belt

New engine gaskets all round

New Thermostat

New NGK spark plugs

R34 GTR injectors

R34N1 turbos C106/GT25 A/R 0.60/0.64

New Rod bolts, welsh plugs

Fresh paint on rocker covers

3" Trust Front pipe and Power Extreme II Cat back Exhaust

3" Metal cat

Twin Apexi Pods

Apexi Power FC & Hand Controller

Greddy Profec B Spec II boost controller

Nismo fuel pump

i've changed spark plugs today checked for blow bye and everything seems fine. I really need some help.

Has any one had this problem before???

Edited March 24, 2008 by black sky

[baboo]

coil pack?

[black sky]

coil pack?

i doubt it's a coil pack because i got split fires not long ago. and some times it rev's out fine but it's just not making the right amount of boost and it feels really sluggish.

i just don't know what to do.

[GTR-32U]

done a compression test yet ? I would start here just to put your mind at ease that its not the engine itself...

[black sky]

done a compression test yet ? I would start here just to put your mind at ease that its not the engine itself...

do you really think it could be the engine?? it's not blowing smoke, it gets onto boost fine, and the engine's been rebuilt not long ago. Oh god please tell me it's not the engine.

[GTR-32U]

it could be a lot of things...but through the process of elimination you will narrow it down to certain areas..once you are 100% that the engine itself isnt the problem then you can attack other areas...Fuel or ignition..is where its most likely at....But first be sure that engine is perfect

[R.3.2.G.T.R]

cleaned your afm?

[black sky]

cleaned your afm?

How do i clean it???

[R.3.2.G.T.R]

buy contact cleaner from automotive store

[GeeTR]

Id check the device that dictates boost; your Greddy EBC. Maybe DC it, and run off the actuator (.5bar?) as a test.

[cefiro]

Hey mate check all your hoses and look for leaks in your intercooler piping BOV etc. I found I had a similar problem with the boost (not spluttering though) currently there is a leak from the gasket going into the last of the throttle bodies (to be fixed next week), worth a try. I made a very simple device from here ( http://www.vfaq.com/mods/ICtester.html ) and blew compressed air into the engine and found it. cost $7 to make and and all you need to do is take off your air box, block one of the hoses from the AFM and place this in the other. (dont need the hosing as on the website just get 65mm PVC end stop fit in nicely)

[Proximity Motorsport]

try your standard coilpacks. My brother bought some splitfire coils for his s14a and they f**ked up in 2000km

[japspec r33]

hey mate, i have the same problem i have nail polished the coil packs, gapped spark plugs but no good i can only get 7 psi to rev cleanly on boost any more than 7 and it is like the rev limiter comes on at 6000 rpm.

i am onto it, will diagnose problem soon and let u know ...

[Adriano]

Could be blocked cat

[Blue32]

My money is on a loose intercooler pipe - specifically the join where the Y pipe of the turbos goes through the front passengers side guard :-)

[Richieb]

Fuel Pump..!!!

[japspec r33]

geetr your the tool

Edited March 29, 2008 by japspec r33

[GeeTR]

hi, i just put a small vid on, this is what my car sounds like to 6000 rpm, quality of vid not too good

on the street

Congrats, your a tool

EDIT: Incriminating 'hooligan' link modified...

Thx

Edited March 30, 2008 by GeeTR

[black sky]

i don't think it's the intercooler piping as it comes on boost as normal and i don't think it's the splitfires because every now and then even on 14psi it revs out but just feels like crap.

but i am going to try that boost leak thing, it looks interesting.

but all indications make me think that it's a blocked CAT.

[black sky]

Ok guys here's an update

I checked the cat all is good i checked the BOV and the same problem is occuring

i disconnected the Boost controller and it's just boosting up to .7 bar and it's fine but it was alway's like that only when i put it onto high boost does it stutter. any ideas???