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1st 2jz 240 swap EVER
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237 Posts
Discussion Starter #1
hey guys im getttin frusterated by my boost cut and i wanted to do a bcc or the ol zenar diode, but because my motor is jap spec (map) i was a little worried about tricking the only sensor controlling my air/fuel mixture. any help appreciated

thanks Dane
 

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1st 2jz 240 swap EVER
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237 Posts
Discussion Starter #3
thanks man i apprciate it...i couldnt really find anything on that site in specific but if you have done it without any problems then ill trust you.
dane
 

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Do the JDM motors have a seperate MAP sensor or does it use the MAP sensor for both boost cut and load sensing? If it uses the same one then hell no don't do it.
 

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the greddy bcc is a great mod i have a j-spec supra and it is wonderful. but remeber the ceramic turbos will go fast. i blew mine out on saturday. so big single here i come
 

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Installation is on the same wire as the US spec.

Keep in mind what you are doing-- you are telling the ECU to calculate fuel and timing based on 1 or 1.2 bar or wherever it starts to hit boost cut, but boosting higher. You might be ok boosting just a little bit higher since the car runs rich from the factory, but I'd be careful, especially if you have a free flowing exhaust and definitely if you are running a bigger turbo. If you're at that stage it would be a great idea to get bigger injectors and a fuel controller.

Shiva
 

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1st 2jz 240 swap EVER
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237 Posts
Discussion Starter #7
the max i plan on runnin is 15-16psi....but id really like to know the only sensor used in the jap ecu for air/fuel is the turbo pressure sensor or if theres a seperate map for that...anyone know :dunno:
 

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1st 2jz 240 swap EVER
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237 Posts
Discussion Starter #10
moneymark that unit looks pretty sweet ill have to look into that when i come across a lil bit of loot.

thanks for the help...i tried the zener diode (4.3 and 1 amp) but had no luck i kinda bench tested it with 4 d-cell battery's and the voltage went to 4.56 (instead of 6.3) so i soldered it into the wires onthe harness. when i fired the car up it ran a little shitty i know the diode drops the voltage to begin with (with 1 d-cell it read 1.02 instead of 1.58 with the diode in line) so i figured it would take a little bit for the computer to get used to it...then i took it out for a drive put it in 6th let the boost come on up to 15 and bam good ol boost cut!? anyone have any ideas.

any help appreciated Dane
 

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1st 2jz 240 swap EVER
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237 Posts
Discussion Starter #11
ok well i just bought a turbo xs defender which has a safet feature that will allow me to hit boost cut at a level i can set i think im gonna set the safety at 18psi whats the word on running that high without a fuel controller...enough fuel inthe system or do i need a fuel controller to be safe?
 

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Supra Owner Since 1996
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I know my US bpu runs pig rich at 18 psi to redline on my 550cc injectors. Your 440's would be at the optimum a/f or lean. Might consider wideband, although I have no experience with the jdm motor. Until next month that is. Tokyo here I come.
 

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1st 2jz 240 swap EVER
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237 Posts
Discussion Starter #13
your goin to tokyo??..thats dope...ive heard that the 440cc high impedance injectors really flow close to the 550 low im pedance because of the on/off nature of the high impedance versus the sinusoidal wave on the low impedance. mainly because the amount of full open time the injectors have. anyone else hear about this...cmon i know theres some jap spec peeps on here :D
dane
 

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Umm, actually when driven by a proper P/H driver low impedance injectors snap open and closed more quickly. Not that the US market Supras got that proper drive <shrug> The sinusodal (sp?) wave you describe is how high impedance and resistor'ed low impedance injectors operate.

You guys do realize what you are doing here right? I've said it before but... You are about to BLIND the ECU from sensing the load on your motor by taking away it's load input. You will cap the load it sees while boost continues to climb. Ignition timing won't retard and fueling will NOT increase. If you use some sort of piggyback fuel thing on it then how will you tune it? Is it seeing it's own load signal? Sure hope so! What will you do about ignition BTW? Rely on the knock sensor to save your ass? Doing this kind of crap without a W/B is insane. Hell, the whole idea is stupid but hey go ahead and see what happens. Before doing so you might want to better understand what it is your doing to the ECU and how it works. If that single MAP sensor is it's only load input this idea is as insane as it gets...
 
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