High Rpm Misfire/spluttering

[Jarrrrrrrrrrod]

hey everyone.

I have a rb25det r31 and just need a bit of help diagnosing this problem.

in neutral and in gear: when on the gas it revs smoothly until it reaches 6000rpm then it looses power and it sounds as if its backfiring/misfiring/spluttering.

more info

.aftermarket turbo

.turbosmart boost t

.intercooler

.sard fuel pressure reg

removing the boost t made a difference from 5000 rpm misfire to what it is now at 6000rpm as well as changing the spark plugs and gapping them to .8 with feeler guages. original plugs where at 1.1 gap

any help is appreciated. thank you.

[Jarrrrrrrrrrod]

also, when I first bought it the previously owner had turned the fuel pressure right up and said he was running aftermarket injectors. he had removed the injectors and replaced them with the originals but didn't change the pressure. I have dropped the fuel pressure back to stock.

any help is really appreciated

[jjman]

if it has different injectors and turbo it will also have a different computer. Be good to know what that is.

otherwise, sounds like typical coilpack or maybe air flow meter (if the computer uses one)

[Jarrrrrrrrrrod]

thanks mate.

it has a r33 ecu. I'm looking at getting either the z32 or r32 ecu and going with the nistune chip once i get all the bugs sorted out. iv cleaned the airflow meter with a store bought spray. I hope it's not the coil pacs, there not cheap.

I have taken the fuel rain out and looked at the injectors, they are a dull purple and not much information stamped on then.

[jjman]

I can almost garuntee that it isnt a stock ecu if it is running different injectors. Stock ecu's cant do it.

to be honest id get that car in for a tune soon and attention from somebody that knows because if you are changing the fuel pressure over the shop you could really run into some trouble and damage the motor.

Be prepared to be throwing coilpacks and perhaps a z32 ecu and even some proper aftermarket injectors at it in order to get it running right, safe, and making some reasonable power if indeed it has an aftermarket turbo on it...

[Jarrrrrrrrrrod]

the turbo looks like it's from eBay. it's a gt35 pcp...? sounds nasty.

z32 ecus arnt the easiest to find. thanks for your help mate

[Jarrrrrrrrrrod]

well iv just blow the head gasket:( so that could be why it was loosing power at high rpm.. bad compression?

iv started ripping the motor apart to check what damage has been done, what else could I be replacing whilst its all apart??