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Rb25 Turbo On My 20 But Now Fuel And Cat Problems Help

335

By 335,
in Engines & Forced Induction

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335 Rising Star

335

Posted
Posted (edited)

Hello

I put a RB25 turbo on my RB20 and it works good, but now I have a lean problem. People smelled the cars lean smell(huh??) but apparently my car is running lean. I had my O2 sensor checked at Nissan(I live in Japan) and the results came back that the sensor is good.

I took off my cat today and someone checked it for me, and I had a look too. There is a 1inch-1 1/2 inch diameter visible space from one end of the cat to the other. Mechanic said that my cat is badly clogged and I need to replace it. He said I can still drive and boost but don't race anyone and don't try to hit high boost. The mechanic also suggested that I should get a bigger fuel pump to allow the car to have more fuel since I have a bigger turbo on there and my car is running lean. I smell it too

The mechanic knows his stuff, so I am wondering how long should I run with a dirty and clogged cat and whats the longest I should wait until upgrading the fuel pump?

Help

Edited by 335
rsx84 Veteran

rsx84

Posted
Posted

quick fix for your cat is take it off and take all the stuff in the middle out then put the cat back in onto the exhaust.... it will stop any issues you are having till you can get a new hi flow one.

fuel pump - just get one from an r33 turbo model should cost you next to nothing..

335 Rising Star

335

Posted
  • Author
Posted

So I do need to replace the fuel pump with a higher flowing one? So the 33's fuel pump is bigger? My friend has a R33 that he is junking, he was trying to take out the fuel pump, but we couldn't figure out how to take the assembly out to get to the pump.

I am tempted to get a Nismo 555cc fuel pump. Over kill?

Help

bubba Grand Master

bubba

Posted
Posted

Bosch 044 pump, mine cost ~$200 and the same again to have a pro fit it and rewire.

Fix the cat pretty soon mate, with a blockage like that your turbine housing will be getting pretty damn hot (I had a blocked cat ages ago and it was making my exhaust housing glow white hot pretty quickly) and ceramic turbines don't like excessive heat :)

nizmonut Community Regular

nizmonut

Posted
Posted

it shouldnt matter what turbo you have on there, due to the fact it is the AFM that measures the air flow and inputs the correct duration the injectors are open for.

just because you have changed turbo's doesnt mean it will run more boost than your old one did...unless you make it ofcourse......i.e.....waste gate actuator.....

factory ecu will boost cut at 16 psi on a rb20det, the fuel pump can handle that, really all you need to do is get a better fuel pressure regulator so it isnt really the issue here,

take the cat off and smash the center out of it, and put it back on, i think you may find that is the issue.

especially if you had to change your turbo cause the old one was shagged.

bubba Grand Master

bubba

Posted
Posted (edited)

Factory ECU will NOT boost cut at any particular boost level.

It is an AFM over-voltage cut and for me on my RB30 (w/ 25 turbo) on standard RB20 ECU that was 12psi with anymore than 3500rpm or 10% throttle.

Fuel Pressure Reg. is BS. Put a decent fuel pump in there and it will be fine.

Edited by bubba
FATAZZ Grand Master

FATAZZ

Posted
Posted
factory ecu will boost cut at 16 psi on a rb20det,

factory ecu,rb25 turbo(stock) 3" turbo back zorst i seen it hit 24psi before it blew

an intercooler pipe off.So i find the above statement incorrect.

bubba Grand Master

bubba

Posted
Posted

^^ agreed.

And I'm sure a GOOD CONDITION stock pump would be fine but these things are 18+ years old and the pumps are getting pretty tired.

Put a Bosch 040 or 044 (preferably) in the tank and rewire it, you'll be laughing.

335 Rising Star

335

Posted
  • Author
Posted

So I need the fuel pump for sure, this pump is from another junk car when mine died last year. So that means this pump will go any minute?

So new cat, new pump and I should be good?

If I am lean why did my 02 sensor test come back good? It did read lean on one of the catergories but the final result said working fine.

What is the longest time I should wait to replace the pump and cat? Which needs to be changed first? Is the X-Force High Flow Stainless Cat any good?

Thanks

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