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Boost Cut

are33

By are33,
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are33 Proficient

are33

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Hey guys i was wondering if someone could give me a brief yet descriptive explanation for boost cut.. My mates skyline gets it and he wants to know how to go about getting rid of it... Just want to know what exactly causes it, What it does and how it can be fixed.

Thanks

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MBS206 Grand Master

MBS206

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Boost cut...

Caused when the turbo supplies too much boost for the stock ECU to handle.

Well, not so much handle, but for the ECU to scream "I WON'T LET YOU HURT THE MOTOR!"

Basically, to avoid it, turn the boost down a touch.

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are33 Proficient

are33

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Boost cut...

Caused when the turbo supplies too much boost for the stock ECU to handle.

Well, not so much handle, but for the ECU to scream "I WON'T LET YOU HURT THE MOTOR!"

Basically, to avoid it, turn the boost down a touch.

Oh ok thanks for that... As soon as he buys a new boost controller ill do that.. (screen broken)

Bloody boy racers :)

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The Dan Grand Master

The Dan

Posted
Posted
Hey guys i was wondering if someone could give me a brief yet descriptive explanation for boost cut.. My mates skyline gets it and he wants to know how to go about getting rid of it... Just want to know what exactly causes it, What it does and how it can be fixed.

Thanks

R33 RB25DET boost cut is around 12psi, R32 RB20DET boost cut is about 21psi.

Are you sure it is boost cut?

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are33 Proficient

are33

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R33 RB25DET boost cut is around 12psi, R32 RB20DET boost cut is about 21psi.

Are you sure it is boost cut?

21 psi on a stock ceramic turbo and stock ecu?

wtfark.

I think it is?

When he gets up it a bit the BOV goes off like a slart and and the car jerks and shudders and it feels like the turbo actually is cutting in and out.. he is running around 14 psi. All he has is pod filter, FMIC, Exhaust system and a bov. not sure of the brands.

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R31Nismoid Grand Master

R31Nismoid

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R33 RB25DET boost cut is around 12psi, R32 RB20DET boost cut is about 21psi.

Are you sure it is boost cut?

There is no such thing as boost cut

The ECU goes into Rich & Retard mapping, it has to do with airflow, not a specific level of boost as such.

OBNXSH - what you are describing sounds to me like its due to the BOV, its ATMO venting correct?

If your mate puts the stock BOV back on there, that will fix the problem for free.

Oh, and 14 isnt safe... the turbo might live, it might not

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are33 Proficient

are33

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There is no such thing as boost cut

The ECU goes into Rich & Retard mapping, it has to do with airflow, not a specific level of boost as such.

OBNXSH - what you are describing sounds to me like its due to the BOV, its ATMO venting correct?

If your mate puts the stock BOV back on there, that will fix the problem for free.

Oh, and 14 isnt safe... the turbo might live, it might not

I see.. Alright ill see how that goes.. Its just weird because my parents used to own a 33 gtst on 14 pounds on the stock turbo, stock ECU with a 60- 40% plumb back BOV the GFB hybrid one, And the same thing happened with that... The mechanic which worked on it (owners of the old hardcore racing in brisbane) said that it was boost cut :S

Weird. maybe its just a nickname or something.

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R31Nismoid Grand Master

R31Nismoid

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Well if its doing it under load, then its Rich 7 Retard

If its playing up when he backs off? Ie, the BOV going off, is he backing off, or is that under full load?

If its under load, then thats Rich & Retard. Backing off the boost will reduce the airflow and make the ECU happy.

A PowerFC or any other ECU will stop that from happening if you wanted to get rid of the problem altogether

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are33 Proficient

are33

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It happens around 4 1/2 - 5k revs, it stops when you back off. it just jerks the car around, its like it cuts out and the car jerks forward then it kicks back in and take off and then stops again and jerks the whole car forward and the only way is to back off the accel all together... its pretty scary when it happens when you dont expect it.. on the odd occasion it happened when the turbo was just spooling (in my parents 33)

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R31Nismoid Grand Master

R31Nismoid

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Just drop the boost till it stops, could be 12psi, could be 10psi.

Only way to know is to knock it down bit by bit.

But it will fix it.

If it doesnt, could well be a coil pack/ignition issue then.

But back the boost off first

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The Dan Grand Master

The Dan

Posted
Posted
There is no such thing as boost cut

The ECU goes into Rich & Retard mapping, it has to do with airflow, not a specific level of boost as such.

OBNXSH - what you are describing sounds to me like its due to the BOV, its ATMO venting correct?

If your mate puts the stock BOV back on there, that will fix the problem for free.

Oh, and 14 isnt safe... the turbo might live, it might not

In two of the stock ECU 32's I did it on, it actually cut ignition at 21psi boost.

The 33's I meant boost limit. (Via solenoid)

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