R33 Top end power problem

[JULZA]

I've got a R33 GTST running a R34 turbo. The car is pretty much stock other than the cheap mods.

Has anyone had a problem when the trubo spools up to full boost that the car gives a struggling sound and can even shudder a bit?

This problem has only started now and happens even on stock boost levels.

My initial thought is that it's leaning out, but I've got a GTR fuel pump so I'm not sure.

Any help would be much appreciated..

[cameron]

If you have front mount cooler/Dumpipe/Exhaust done, it should be breathing fully and not strugling uptop.

Leaning out won't make it struggle - as you said you have a bigger fuel pump and with stock R34 turbo - it should'nt lean out.

What boost are you running & what else is done to the car ?

Jun

[JULZA]

I was initally running about pound but since the problem started I've kept it at about 5-6 pound. both of which are pretty conservative levels.

other mods are pretty basic; exhaust, BOV, boost controller, intake etc.

[cameron]

Do the dumpipe from the turbo to cat.

&

Front Mount Intercooler.

Maby try changing you'r spark plugs aswel.

This should help.

Jun

[tang0]

Do the dumpipe from the turbo to cat.

 

&

 

Front Mount Intercooler.

 

Maby try changing you'r spark plugs aswel.

 

This should help.

 

Jun

theres a grand easily !!!

might just be worth changing the fuel filter ... often overlooked, but can often be a cheap quick fix as well if the current one is full of cr@p

[cameron]

Yeh True

JULZA,

describe the sound more, is it a missfire or a knocking sound ? I'v never herd struggling or shudder. - what rpm is this happening ?

[JULZA]

The spark plugs were just changed, the platinum kind which cost a packet!

The Fuel filter sounds like a possibility cause I dunno when it was changed last.

The rpm doesn't show any signs of struggling when the problem occurs, the other thing is that if I put my foot down and bring the boost just a little shy of full boost it's fine.

So it only happens when I floor the car. The car doesn't really shudder as such it's more of a audible issue and power drop out (from the turbo). When at full boost it's as if it is being floored then eased off then floored, so it cuts in and out of sounding like normal.

It's bloody hard to describe but it's never happened before and annoying.

I'll test the fuel pump flow and check out the fuel filter and let you know.

[JULZA]

Cam,

in regards to your comments, the dumpipe does go from the turbo right back (3")

and I've had the cat knocked out, so I doubt its an exhaust flow issue.

[Sydneykid]

The spark plugs were just changed, the platinum kind which cost a packet!

What gap?

[joh21m]

sounds a lot like the problem i have now with my rb20det...when i hit 5500rpm, power drops from 122rwkw to about 80rwkw, mechanic has suggested new coil packs which i ordered about 5 weeks ago and still havent arrived. I dont think its gonna fix the prob but i will let you know how it goes...

maybe you should put it on a dyno aswell...i found my car is running super rich as SK pointed out, im looking at an safc to correct this...

i'll let you know how it all goes...

Joh

[fresh]

too much boost on the stock ecu, it'll pull the timing and and dump in fuel like a bitch, dunno your problem might be worse then that but the stock ecu don't like much more then 10psi, maybe its time for an aftermarket ecu, u seem to have done everything else

[shif_tea]

dirty afm??

[JULZA]

yeah,

I've thought about grabbing an apexi AFC but cost is an issue.

The reason that I don't want to go down the computer path is because it was running high levels of boost with no problems for ages, and now on stock boost it does it so it can't be the stock ecu struggling.

[600hp]

i've had the same problem with an audi

we were having probs at higher boost but when we wound it back down the problem was still there, and we traced it back to faulty coils, thanks to the computer telling us which coil was stuffed.

[tang0]

tried resetting the ecu and making it relearn all the stuff

[ricknismo]

Fixed??