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Rb25det always blowing black smoke at high boost/high revs

IM-32-FK

By IM-32-FK,
in Engines & Forced Induction

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IM-32-FK Mentor

IM-32-FK

Posted
Posted

Hey all,

since I bought my r34 way back in 2015 my car has always been running a rich.

It’s just an unopened 25det neo with the stock op6 turbo running just above 12psi , with a blitz front mount, turbo back exhaust with cat, apexi intake, oil cooler and a power fc tune.

the thing is the car runs without problems, but when you start revving it past 4500rpm hard and pretty much 12psi or close, it blows a lot of black smoke . So much so that I get soot everywhere on the back of my car and my bumper just above the exhaust is permanently stained .

I know running rich means it’s using more fuel then needed but is there more to it? I regularly service my car and change spark plugs every service too (bcpr6es -8). 

There isn’t anything wrong with how the car runs. It actually runs perfect. No idle issues, no boost cuts, no pinging, no stuttering when climbing revs etc

Is there anything I can do to reduce the black smoke? Or is it just the way it is?

IM-32-FK Mentor

IM-32-FK

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15 minutes ago, KiwiRS4T said:

What do your plugs look like when you change them?  Do you have a dyno chart of the afrs? Have you done a compression test?

The tips are always white, and the thread on the spark plug is black going down about 10mm. Don’t have the dyno sheet or compression test sheet. Never did it since I bought it. Also, the engine is at 246,000km

Ben C34 Grand Master

Ben C34

Posted
Posted

Reading plugs doesn't count for much unless you put fresh plugs in, do a wot pull and shut it down straight away.

I would put money on the tune is too rich in the boosted areas and lean/ok in the cruise areas

 

Get it tuned

IM-32-FK Mentor

IM-32-FK

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14 minutes ago, Ben C34 said:

Reading plugs doesn't count for much unless you put fresh plugs in, do a wot pull and shut it down straight away.

I would put money on the tune is too rich in the boosted areas and lean/ok in the cruise areas

 

Get it tuned

No point now. I’m gonna go max hp without unopened motor, for rb25 it’s about 450hp right?  New turbo with supporting mods such as fuel pump and reg, ffp, z32 afm injectors etc then I’ll even sack the power fc (because it has fuel cut) get it tuned with either a nistune or ems 6860 so I can get 2 step and anti lag.

GTSBoy Grand Master

GTSBoy

Posted
Posted
15 minutes ago, IM-32-FK said:

reg, ffp, z32 afm

All of this is wrong.

 

16 minutes ago, IM-32-FK said:

sack the power fc

This is OK, but unnecessary, because

 

16 minutes ago, IM-32-FK said:

because it has fuel cut

This is wrong

16 minutes ago, IM-32-FK said:

2 step and anti lag

Do you hate your driveline?

  • 2 weeks later...

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