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Speed Cut And Boost Cut

WogsRus
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WogsRus Veteran

WogsRus

Posted
Posted

I know. before you say it, i have used the search.

What i need to know is if i cut sire #53 on the ecu, however i have heard that this disables your HICAS. Since i like HICAS how else can i remove it, or will cutting the #53 output fix this, Has anyone done this? If so does it work.

ALSO how do i remove the Boost cut and how does the boost cut work. I was going to get one off these, Gizzmo FCD,

http://www.nzperformance.co.nz/store/view_...hp?product=GFCD

But i have no idea where to get one here in OZ. Are these worth it, and do they work well.

How does the boost cut work and when does it come on or how is it determined by the ECU that it needs to be on.

OK thanks. This is a bit urgent, i need to get the car ready for track in two weeks.

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https://www.sau.com.au/forums/topic/129402-speed-cut-and-boost-cut/
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WogsRus Veteran

WogsRus

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I forgot to mention that it is a 95 R33 GTST.

I have a friend who is a wiz with electronics, so he can make something for me, just not sure how the boost and speed cut work?

Can somone clarify how the speed and boost cuts wort on a R33?

Wink Grand Master

Wink

Posted
Posted

Boost cut is the wrong term for it, as the 'cut' has nothing whatsoever to do with boost/pressure levels.

The right term is "Rich and Retard" - do searching in the forum on this term instead of "boost cut" and you may find better, more technical answers, especially from Sydneykid.

Basically when you turn up the boost on the RB25DET, your fuel/air mixtures will be very rich at the top end (down to AFR of 8-9). The ECU will then retard the engine as a reaction to overly rich fuel/air mixtures.

satanic Grand Master

satanic

Posted
Posted

The new Turbosmart FCD works a charm so I've heard; perhaps call them up and get some more details on it.

The Speed Cut can be removed by simply cutting the wire; look up the ECU pinout manual to find out which one.

WogsRus Veteran

WogsRus

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only problem is i have no money for a PFC, but enough left to get a SAFC II, plus sometimes these come up cheep.

UPPPSS i better tell my mate not to cut the wire, he was goign to do it, but has an auto.

Thanks mate.

Either way, would using a SAFC II to lean out the mixture, fix the boost cut retard?

mad082 Grand Master

mad082

Posted
Posted

a mate of mine cut a speed wire (don't know which 1) and it got rid of his speed cut.

as for rich and retard, a safc won't get rid of it. it has nothing to do with air/fuel mixtures. it is to do with the amount of air passing through the airflow meter at any given rpm. it isn't just when you get to a certain pressure it cuts out. the amount of airflow might be ok for 4000rpm, but its too much at 3000rpm, so the ecu kills the engine for a second to slow the turbo down. then the engine will kick back in and continue on as if nothing has happened. you don't lose power after it has happened, just for the time that it kills the motor. when mine would do it it would proceed to light the tyres up down the road when it kicked back in if i was in first or second gear.

mad082 Grand Master

mad082

Posted
Posted

i would also have to suggest the new turbosmart fcd over any of the others i have seen, as it has a set of instructions just for skylines.

but ultimately a full ecu, or a remapped ecu would be better. i picked up a remapped r33 ecu for $200. it was remapped in japan. it has no speed cut, higher rev limiter and no airflow protection.

WogsRus Veteran

WogsRus

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So the cut, feels like a missfire then, or what? The car will be in Tassie on Monday, and as soon as it comes in, it's getting a new IC, new exhaust, boost regulator, fuel pump. I am planing on running 10-12psi on the stock turbo for now.

What are my chances of incountering boost cut, and is there an easy way to get rid of it.?????????????????

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