Jump to content
SAU Community

Recommended Posts

Hi guys and girls,

I've recently bought a R32 GTS-4 with an RB20DET. I'm in the process of fixing it up and while I've read hundreds of pages on here and random Google pages i still have a problem with it not making full power.

So i'll start with a background:

RB20DET

RB25 turbo,

FMIC,

Brand new copper spark plugs 0.8mm (BCPR5ES)

ECU Diag came up 55, All ok.

(I think i did it right)- O2 sensor came up as the car running rich, LED didn't flash at all.

So, The car runs fine, it boosts to 10psi and its all happy days. However the power band is at like 3/4 throttle and it runs slower when you open the throttle full. Boost is still the same at 10psi.

The exhaust does "pop" every now and again and i'm pretty sure that's just because its running rich.. The car doesn't misfire as far as i can tell but it's not making much power even when gently getting it in that "sweet spot" it does about 16.5s down the drag strip with a 2.1s 0-60 time. so maybe 120awkw at best?

Is there something wrong with it or would a simple dyno tune fix it? I'm not too keen on going to the dyno just yet as i plan to get a 040 fuel pump + injectors and Z32 afm and do it all at once.

BTW, My name is Steve and i'm from west Brisbane, picked up the car recently and i love it! I get my open license at the end of the year so at the moment I'm just cleaning it up and getting some power out of the almighty RB20 for the occasional track day! I can see myself joining the SAUqld club too.. love these cars.

Link to comment
https://www.sau.com.au/forums/topic/336420-r32-power-drop-at-wot/
Share on other sites

The stock rb20 turbo was leaking so the previous owner just put in a RB25 turbo, no idea on its history... Anyway to check for steel wheel/highflow? Pulling the turbo completely out to check would be a pain.. and running high boost and blowing the probable ceramic wheel would be bad.

Also yeh i understand i need a new ECU or piggyback system for it. If it does need a tune, is the stock ECU tunable at all? or ONLY with an aftermarket solution?

Edited by sholm23

A hiflowed RB25 turbo will flow more air at 10psi, than a normal RB25.. and in turn a normal RB25 turbo will outflow a stock RB20 turbo at 10psi. What you're experiencing could be what we call R&R (rich & retard), which is a ECU safeguard to protect the engine as the stock ECU by itself isn't very good at supporting higher than stock power.

That makes sense, i took it for a quick drive and it pulls alot harder ar 5-6psi.. which i'm now assuming is the same amount of airflow the stock RB20 turbo was putting out at 10 psi. Now with a highflowed RB25 turbo at 10psi its putting out more air then the ECU can handle and now it needs a tune? Sounds pretty right to me but im still learning alot.

Heres a picture of the turbo as it sits in the car.. I highly doubt anyone can indentify a highflowed turbo by just the front but its worth a shot... I don't wan't to pull the turbo out of the car to check it because i'm not sure what im doing just yet lol. One thing i notice though is that the old RB20 turbo (i still have it) has double the amount of fins, like the normal 6 fins as shown below but with a sort of secondary fin just below the first, making 12 fins. Is there anyway at all to tell if it is? I really hope its the case but i don't want to push more psi then it can handle and blow it up if im wrong.

12092010441.jpg

Here's what a Hiflowed RB25 turbo looks like (notice how thin the housing has been machined back to): http://www.digi-hardware.com/images/r33PU/pufront.jpg

By the looks of it it's a ceramic wheel, but im not 100% sure.

Well so far i've found that its only the exhaust wheel that is ceramic. Only way to test for sure is to have a look at the exhaust wheel and see if the nut is a 6 point hex (steel) or 12 point hex (ceramic). I've looked at alot of pictures on here of my turbo and some people say its a nylon compressor wheel and others say its a metal one? either way if its a ceramic exhaust wheel the ceramic wheel will go first...

So assuming its a stock RB25 series 1 turbo, at 10psi i need an ECU remap to get full power at full throttle? Done.

Now i gotta figure out if i can run 14psi on stock fuel/ignition setup with an ECU remap...

standard rb20det ecus love 25 turbos . at 11.5 psi the injectors are pretty much maxed and afrs are safe itll be 195 kw at the hubs and run a 13.0 if its in a s13

you checked your fuel filter and pump ? that would do it . not enough fuel up top

i was thinking the same thing, bcpr 6 es.

like everyone has said, get a nistune fitted and tuned or any other aftermarket tuneable ecu, but call your tuner and find out what they like to tune before you go buy one,

Almost certainly just the stock tune giving you grief, although in case it is something like clogged injectors or the fuel pump get it on the dyno and make sure it is not leaning out as this will kill your motor.

Does it blow lots of black smoke when it starts to die? If so then a nistune and a proper dyno tune will almost certainly fix your problem. Don't need the Z32 afm unless you are aiming for 230kw+

Edited by Rolls

I'll change out the plugs tomorrow to a BCPR6ES maybe a 1.1 gap too. Will change out the fuel filter aswell. If i was to put in an aftermarket fuel pump, like a Bosch 040. I don't need a tune straight away do I? fuel pump wont affect anything unless i swap out injectors right? I might get one of those too, just to kill 2 birds with one stone.

I can't afford an Aftermarket ECU for while so i'll try all this stuff first before i get a tune. As long as im not running lean i'm more then happy with lost kw's until then if a tune is needed.

A new fuel pump won't affect the tune at all, the Fuel Pressure Regulator makes sure of that. Though it is highly recommended to change the pump on the safe side anyway, since they are 20 years old, it might be struggling now, so more power won't help it.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Hi guys . Can someone help me  I bought an Android screen for my Nissan fuga but it won't turn on   
    • My guesstimate, with no real numbers to back it up, is it won't effect it greatly at all.its not a huge change in position, and I can't see the air flow changing from in turbulence that much based on distance, and what's in front of it. Johnny and Brad may have some more numbers to share from experience though.
    • Which solenoid? Why was it changed? Again, why was this done? ...well, these wear..but ultimately, why was it changed? Did you reset the idle voltage level after fitment? I'm just a tad confused ~ the flash code doesn't allude to these items being faulty, so in my mind the only reason to change these things, would be some drive-ability issue....and if that's the case, what was the problem? Those questions aside, check if the dropping resistor is OK ...should be 11~14 ohms (TCU doesn't throw a flash code for this) ~ also, these TCU designs have full time power (to keep fault code RAM alive), and I think that'll throw a logic code (as opposed to the 10 hardware codes), if that power is missing (or the ram has gone bad in the TCU, which you can check..but that's another story here perhaps).
    • Question for people who "know stuff" I am looking at doing the new intake like the one in the picture (the pictured is designed for the OEM TB and intake plenum), this design has the filter behind the front bar, but, the filter sits where the OEM duct heads into the front bar, and the standard aperture when the OEM ducting is removed allows the filter to pulled back out of the front bar into the engine bay for servicing, a simple blanking plate is used to seal the aperture behind the filter This will require a 45° silicone hose from the TB, like the alloy pipe that is currently there, to another 45° silicone hose to get a straight run to the aperture in the front bar Question: how will it effect the tune if I move the MAF about 100-150mm forward, the red is around where my MAF is currently, and the green would be where it would end up Like this This is the hole the filter goes through  Ends up like this LOL..Cheers    
    • Despite the level up question, actually I do know what that is....it is a pressure sender wire.  So check out around the oil filter for an oil pressure sender, or maybe fuel pressure near the filter or on the engine. Possibly but less likely coolant pressure sensor because they tend to be combined temp/pressure senders if you have one. Could also be brake pressure (in a brake line somewhere pre ABS) but maybe I'm the only one that has that on a skyline.
×
×
  • Create New...