Just Installed A Rb25det Turbo On A Rb20det Engine, Having Problems! Help!

[bax_nz]

hey dudes

i have rb20det

full inch exhast

600x300x76 intercooler + piping

pod filter

gtr fuel pump

ecu (mines chip)

and just installed new rebuilt rb25det turbo (by steve murch, new bearings still the same wheels)

now before i installed the rb25det the original rb20det turbo was boosting 12psi (about 0.9 bar)

i ran the car for the first time tonight with the rb25det turbo on and the cars power feels the same but its only boosting 0.55 bar???

Should i be buying a boost tap and cranking this to 1 bar (14.7psi)?? and getting what this turbo can really achieve?

have i done something wrong?

if i need a boost tap wat would be the cheapest recommendation???

any help would be great thx

[Birnie]

If you didn't swap the wastgate actuators over, that could be it.

and your settings were different bi 0.35bar which is right on 5psi

R32 standard actuator is set to 10psi.

R33 standard actuator is set to 5psi (....i think with the R33 boost solenoid tweaking it to 7psi over 4500)

If that the case (which it looks like it is), spend 20mins swaping the old actuator back in

[InterCooL]

  Birnie said:

If that the case (which it looks like it is), spend 20mins swaping the old actuator back in

^^ what he said

[MANWHORE]

spot on the money birnie.

Since he won't have the 2 stage solenoid, with just an r33 actuator, it runs about 4.5 psi. since he's got a few mods like ic, exhaust etc, it'll run a bit more - that's the 5.5 psi.

pop the 32 actuator in and i won't be suprised with your extra mods if you get 11-12 psi. she'll rip really hard.

[bax_nz]

  MANWHORE said:

spot on the money birnie.

Since he won't have the 2 stage solenoid, with just an r33 actuator, it runs about 4.5 psi. since he's got a few mods like ic, exhaust etc, it'll run a bit more - that's the 5.5 psi.

pop the 32 actuator in and i won't be suprised with your extra mods if you get 11-12 psi. she'll rip really hard.

is it pretty hard to do???

i know how to take pipes off the car and unbolt stuff but do i need to set anything?

cheers

[bax_nz]

  bax_nz said:

is it pretty hard to do???

i know how to take pipes off the car and unbolt stuff but do i need to set anything?

do i need to take the whole turbo off or can i do it with the turbo still in the car?

cheers

[Birnie]

2 bolts to undo on the actuator side, and a 'C' clip on the end where it attatches to the gate.

Put on the R32 one in reverse order and that's it. It should be a straight swap out.

No settings unless you have a boost controller or something to play with

[bax_nz]

hey dudes

i changed the unit over

and i reset the ecu

boost is now around 10 - 12 psi

but im now loosing power and the engine is slightly popping at 4500 - 5500 rpm

do i need to replace the injectors or fuel regulator or a retune or something?

cheers

[MZTRBO]

FYI,

The spring in the rb25det acuator is 7psi rated. Which is 0.55bar i think?

The 5psi is controlled by the ecu then after 4500rpm it grounds the black wire coming from the elec boost tap deivce and runs 7psi from the actuator.

I ran a rb20 actuator on an r33 turbo and it would run 5psi then after 4500rpm 10-11psi...I cut the black wire going to the ecu and then it never ran 5psi anymore..

Cheers

[MZTRBO]

could possibly be R&R not to sure with an rb20ecu...the computer seems to be running it rich then retarding the ignition to prevent it from leaning out.

[MANWHORE]

fyi mzturbo, it is not set at 7 psi. well, not on the stock turbo anyways. With just my stock turbo, I connectected the stock solenoid system up. Because I had exhaust and cooler, I was getting 9psi.

with just the actuator, I was getting 5 psi.

The solenoid is a bleeder. The actuator is 5 psi, it bleeds a little air above 4500 rpm, so it gets a few more psi. not the other way round.

Edited May 11, 2007 by MANWHORE

[MZTRBO]

You may be right

[MZTRBO]

I am a little confused now.

[MZTRBO]

Doesnt matter now as im running an rb20det actuator haha...

it was a great improvement..

nyway

bax nz go for tune and it'll fix your issues.

[InterCooL]

  bax_nz said:

boost is now around 10 - 12 psi

but im now loosing power and the engine is slightly popping at 4500 - 5500 rpm

do i need to replace the injectors or fuel regulator or a retune or something?

cheers

the joys of a misfiring skyline

there a billions of threads on misfire

increased boost = harder for spark to jump on plugs = misfiring

solutions? bringing down gaps on plugs = cheapsolution, you still have a weak ignition system

spitfire coil packs = $560 from sliding, it'll fix it

or you could do your own wiring up of igniter's and leads for $100-300, lots more work, theres a few threads about it here and on other sites

[MZTRBO]

intercool is right,

my car done the same thing when is was in R&R mode as it did when it was misfiring.

I had 1.1mm plugs regapped them to 0.6 and the misfiring went completely..

the R&R a tune sorted that out..

[bax_nz]

i have gtr injectors sitting next to me

would u recommend putting these in with a new fuel regulator or something too?

what type of spark plugs and what gap am i aiming for? 0.8mm? ngk or something?

cheers

[BHDave]

ngk bcpr6es which are a .8 gap. It should help with the mis fire unless your coils are absolutely rooted. If it doesn't then either new coils or one of the many fixes that are posted in the maintainence sticky thread.

Dont worry about injectors and regs for now. fix the miss first.

[dangerous_daveo]

Dude its just a standard RB25 turbo. You really shouldnt need to do much. Just keep gapping the plugs down until it stops miss firing, assuming that sovles the problem. If it does it still means your ignition isnt up to sratch (which is expected as the car is a good 15+yo). You could maybe just put the fuel reg on to be a little safter.

[Links]

On a side note did you say that the exhaust wheel is still the ceramic one? I would be cautious as to how much boost you run through it e.g. no more than 12psi..