R32 Power Drop At Wot.

[sholm23]

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.

[Moodles2]

It's possible the RB25 turbo might have been hiflowed and got a steel wheel too, could explain the laggyness.

[KiwiRS4T]

Z32 afm won't work with your ecu - you will have to get a Nistune chip and get it dynoed.

[sholm23]

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 September 11, 2010 by sholm23

[Moodles2]

Stock ECU tuneable yes, with a daughterboard. www.nistune.com

[Dobz]

If you're in melbourne dr drift can re-tune a stock rb20 ecu.

[sholm23]

Ok thanks for the info, Might look into a Nistune board sooner rather then later. Is the problem i have related to a bad tune only? Would bolting on a presumably stock RB25 turbo affect the car in this way? why?

[Moodles2]

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.

[kwickr33]

But doesn't stock ECU run less timing full throttle then partial throttle?

Edited September 11, 2010 by kwickr33

[sholm23]

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.

[Moodles2]

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.

[sholm23]

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...

[lachlanw]

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

[joeyjoejoejuniorshabadoo]

i'd also look at going up a heat range or 2 in your plugs

[DVS JEZ]

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,

[BenSm]

try changing your fuel pump. fuel pump might not be keeping up. had it with my car, couldnt hit over 10psi without it jumping up and down.

[Rolls]

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 September 14, 2010 by Rolls

[sholm23]

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.

[Rolls]

A nistune is only $300 and about $300 to touch up the standard setup, it doesn't need a full tune from scratch as you have stock turbs etc, best bang for buck out of all of those options.

[Moodles2]

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.