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Rb25det Full Throtle Problem

z-monster

By z-monster,
in Engines & Forced Induction

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z-monster Rookie

z-monster

Posted
Posted

hey guys,

i have a serious problem with my rb25det as i have recently installed a greddy type intake manifold and a HKS exhaust manifold where the turbo mounts at the bottom of the extractor. With these new installements into my engine, i have maintained my standard turbo and an external wastegate which is fine so far. my problem occures at cruizing speed in fifth gear. i'll have my rpm below 3000 and as i gradually lean deeper into the accelerator till full throtle and the rpm is building fast towards 6000 and i'm pushing full boost of 0.9 bar, i will suddenly have a power cut from the engine. there will be a 2 second wait till my engine actually decides to start pulling with power again... what could this be???

i suspect that the air fuel mixture is not right maybe i leaned out too much or could it my ECU (standard by the way) going into limp mode as i detects some error? is it a fuel cut or is my fuel pressure not enough? i'm currently pushing 60 psi of fuel though my sard fuel press regulator. i'm also running a 280lph fuel pump and an external wastegate with a HKS pod filter. standard injectors, ecu, cams, and cam pulley, standard rb25det throttle body as well. i have gone mad trying to figure out what the problem is and i have exhausted all possible suspects short of getting my car on a dyno and upgrading my ECU. so i hope someone in this forum could come to my aid.

i have not experienced this problem in any other gears accept maybe once in forth but it always happens in fifth gear.

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https://www.sau.com.au/forums/topic/140003-rb25det-full-throtle-problem/
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blind_elk Grand Master

blind_elk

Posted
Posted

60 psi is a bit too much - standard is around 37 psi, rising to perhaps 50 on full boost.

So, the engine will be running richer than normal, and I've heard recently that too rich can also cause knock.

Try backing off the fuel pressure a bit.

bazr33 Mentor

bazr33

Posted
Posted

seems to sound like what yours is doin, happened to me

i changed to a pod air filter, and cause it wasnt tuned for it, as i gradually put my foot down in fifth, as boost came on , it starting hesitating.

Have ya tried doin it putting down your foot in fifth with just standard boost (6psi). And see what it does.

But i think ya pretty much right, after changing ya intake manifold, there would be a different flow of air changing your air/fuel mixtures.

And the standard ECU doesnt recognise it.

Would like to know what it is

If i was in your position i would be savin for a PFC, and a tune.

If you are located in Brisbane i know the best place to go.

Abo Bob Grand Master

Abo Bob

Posted
Posted
5th gear, approaching 6000rpm.

Standard ecu.

This would be at speeds right around 180km/h wouldn't it?

It might be the 180km/h cut out you're experiencing?

Then again, I might be totally wrong...

-Insu

That's what I was thinking.

Where are you doing 6k in 5th?

z-monster Rookie

z-monster

Posted
  • Author
Posted (edited)
Yeah I was thinking it was a bit high, but he does say 'approaching' 6k.

So yeah, just a thought.

.

oh ya guys.. i have to tell yall i have gone to 250kmh on my car with standard boost before... i have a speed cut chip already installed. :laugh: sorry to have left that out :no:

one more thing is that i have started to notice the problem presisting on 3rd, 4th and 5th gears now that i have lowered my fuel press to 55 psi. the possibility of having turbo overboost keeps coming up as suggested by mechanics as i explain my problem to them... what the hell is turbo over boost??? i am only boosing a max of 0.9 bar on my rb25det stock turbine...

Edited by z-monster

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