Boost Issue ?

[Lrs94]

So I recently bought an old r32, when I got the car it was running fine at 14 psi, but the turbo seals where gone on turbo and used to blow a little smoke under load, so I swapped it with and rb25 turbo, and this is where my trouble begins, if I run the factory 7 psi the car runs perfect all the way up to redline, but I want a bit more than 7 psi, so I put the old 14 psi actuator on the new turbo, and soon as it goes above 7ps in any gear the wholes car just kind of, shakes/stutters/hesitates quiet violently back and forth.

I disconnected the line to the actuator, so now the only thing controlling the boost should be my foot on the throttle, but same thing happens, soon as I go over 7 psi the whole car, shakes/stutters, and you cant get past this point, ie, can rev any higher/gain speed, until you change gear.

things I have tried.

-different actuators

-different turbo

- gapped plugs

-checked coil packs (they look fine to me, but might try tape them)

-changed fuel filter

-check led on ecu no fault codes

-cleaned afm with contact cleaner

checked for boost/vacuum leaks (I am sure there is no boost leaks as I can see boost from about 2.2k rpm

should be getting a consult cable this week so hopefully that will shed some light, just want some more ideas on where to look, what to look for, what would limit boost ?

[scotty nm35]

So you stuck a much larger turbo on, untuned, and you wonder why the ecu is trying to protect itself?

Perhaps it should just let you melt the pistons...

[1400r]

fuel pump?

and run less boost like 10psi and go from there

[Blackkers]

you're essentially using an aftermarket turbo. it will flow more air for the same boost level seeing as it is 'bigger'. to get the car able to drive well you need aftermarket tuning.

now you can probably get away with most of the factory bits already on your car but for peace of mind I'd install a fuel pump, Walbro GSS341 ($100) and go for a nistune ECU and tune (roughly $1,200 all up).

This will allow you to boost up to around 15 or so psi on the RB25 turbo and the car will run nicely.

The cheaper option is to install another RB20 turbo and go back to where you started.

[Blackkers]

Also about boost leaks. If a leak only occurs at 5psi or so it won't be evident until then. so just because it produces boost at 2.2k doesn't mean it's not leaking

[Lrs94]

So you stuck a much larger turbo on, untuned, and you wonder why the ecu is trying to protect itself?

Perhaps it should just let you melt the pistons...

Both turbos are rb25, same turbo it ran 14 psi perfectly fine before, it has nistune type 2 board, which has be tuned not long ago.

[GTSBoy]

Should have said at the beginning. So many threads go this way.

[Ben C34]

Pressure test.

Only way to be sure of leaks