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The mkiv Supra Owners Club

Boosting, and the colder weather


DamanC

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Hello oh technical ones. Firstly i should say, i dont come here often, i simply dont fit in..........read as 'i dont know a great deal about the technowobble stuff'

 

A little background on my car;

 

96 JDM TT

Envy Double decat

Custom exhaust

Walbro fuel pump

IK 24's (i think, the bpu ones)

HKS pannel Filter

GReddy Profec B II Boost controller

Thor FCD

 

A kind member of the forum helped wire up my loverly BC, and help set it up. Upon using the same settings as him my boost levels were around 1.35 BAR, surfice to say i stayed off WOT until i could borrow him for another set up.

 

We set my 'gain' to 30% and my 'set gain' to 0.50. What this achieved was an initial boost to around 1.25 bar, and then after a second or so the boost would drop to about 1.18bar where it would remain whilst on WOT. Now is this normal for my car to boost that high and then settle down?

 

Secondly, now with the colder weather my initial boost reading peaks now at 1.28BAR, a slight increase. I have no idea what it settles down too as im too busy hanging on! Is this ok, or should i be winding my BC down a little?

 

A little advice as to why the peaking happens and if this is normal would be great fellas :)

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well I'm no expert but

 

boost will go up when the air is cooler, cooler air = denser air

 

approaching 1.3 bar is a bit high for j-specs, they may be fine or go pop, it is just an increased risk

 

but if it is just peaking at 1.28 and then settling down lower around 1.2 then that is probably ok

 

suprised about the overshoot though, I'm sure some BC experts will be along to tell you why this is happening. Have to tried adjusting the gain to see if it affects the overshoot?

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What boost does it actually make with the boost controller switched off (top left button for a few secs on the b spec II iirc)?

 

It sounds like the gain and set gain settings are too far apart, which can cause this kind of scenario.

 

There is also another setting, 'Set', on this controller - adjusted by the big turny nob. This is your settled boost level if you like, the other two are to do with spool up.

 

Cheers,

 

Brian.

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