RB25DET s2 cutting off rpm at 5k

[Lowkey_RB_Kouki]

If I get into boost sorta fast the engine will cut at 5k rpm. If I slowly get into it it'll let me pass 5k without cutting but won't go over 5psi and  also after 5k it'll die sometimes or bog. My shop has checked about everything and they can't find the problem. They told me the only thing I can do now is to run a standalone ECU. I'm fine with that but kinda worried about not being able to run a closed loop so it doesn't waste gas. Any input ? Very much appreciated 

 

[vxsr33]

How much boost are you running? Stock turbo?

[Ben C34]

Check for boost leaks..

Many Stand alone Ecu's can still run closed loop but that's not the be all and end all to get good economy anyway.

[admS15]

 

Added bonus, stand alone ECU's can do this.

 

You can also use it to run NOS, the good gas[emoji95]

 

[Lowkey_RB_Kouki]

I was running 8psi before the new RB25 swap. Stock turbo 

[Trex]

You can use closed loop on most aftermarket ecu's... 

 

There is a mechanical problem, you are only going to mask the issue with a tune, until that issue gets worse.

Take it to another workshop.

[vxsr33]

When did the problem start? Or has it been like that since the swap?
I would start cheap and easy. Such as check for boost leaks, clean coilpacks, new sparkplugs gapped to 0.8, change fuel filter.
The stock ecu should be fine at 8 psi, it shouldn't have any R&R issues. If you have a boost controller you could just quickly bypass it and run stock wastegate pressure to see if it fixes the problem at all.

[Lowkey_RB_Kouki]

Started since the swap was done. No boost leaks, coilpack has been checked/tested, new spark plugs and the plugs have been gapped 

[Trex]

What exactly has the workshop tried? Strange problem

[Ben C34]

 Pressure test to find boost  leaks.

 

What ecu?

[Lowkey_RB_Kouki]

It isn't a boost leak and it's a stock ecu at the moment. I've been told the only way to fix this problem is to get a standalone ECU. 

 

[Ben C34]

Fix what?

[Lowkey_RB_Kouki]

The engine is cutting at 5k rpm. If I slowly build the rpm's up it'll rev all the way up to 7k. If I build the rpm's up fast once it hits 5k rpm it'll cut and bog out 

[Ben C34]

They are the symptoms.

I doubt caused by the ecu. 

Have you pressure tested to check for boost leaks? Or just think there are none?

Check fuel pressure also 

[Lowkey_RB_Kouki]

I have a fuel pressure gauge 

[Trex]

sounds like boost cut to me, going off the info we have haha.

 

Put the vac line from the actuator to the intercooler and see what happens.

[Trex]

And obviously a small boost leak with a maf car.