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Discussion Starter #1
Got my FJO installed this weekend, went out to do some tuning runs on the expressway and found out that under low boost (~8 PSI) the car wants to run in the 13.5-14.0 A/F range while under normal boost (~18 PSI) it wants to run pig rich. The FJO display does not go below 10.0, I saw a lot of that under full boost. When I tried to lean it out, the low boost numbers got leaner but didn't affect the high boost enough to show up on the display. I found out the GCC can be used to tune based on boost and not RPM, but only when used with the F-Con (bastards!) so I can't use that trick

The HKS site was about as useful as a football bat when I tried to find out if there are alternative chips available for the VPC so can anyone point me in the right direction?

BTW, the car is an A/T with a small single turbo conversion and a rather large FMIC, stock fuel system except for the rewired pump

Rob_O
 
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Discussion Starter #3
To the best of my knowledge it is a chip for the stock twins. The previous owner went from sequential to TTC to a single and AFAIK he never changed chips in the VPC. I am sure he didn't give me any other VPC chips in the pile of misc. parts that came with the car

Rob_O
 

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IMO I would pop open the VPC and check the number on the chip. You can post the chip number and someone can tell you what chip that is. Also if you post the number on the chip and someone dosen't beat me to it I'll check the number, on the new chip I just purchased for the 720cc injectors.

94TT BPU+
11.62 @ 121.11
No NOS or VPC

In my garage gettind T78 and fuel.
 

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Formerly jza8shwoff
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All the chips are listed on the HKS USA site:

http://www.hksusa.com/products/?id=863

scroll to the bottom, you will see all 5 chips that are offered for the supra, as well as thier part #s and specs. Just click the "more" button and it will give you the detailed specs of each chips specific application.

The chip that you probably are looking for is the JZA8018B

Assuming that you have an AT, what you might have in the VPC now is a JZA8018AT.

Let me know if you need any other info.
 
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Ok, I figured out how to use the little arrows to scroll down on that page and no listing for single turbo/stock injectors. I guess at this point about all I can do is try whatever stock injector chip I don't have and hope it's better since the GCC will probably not have enough range to use the stock injectors with a 680 chip.

Anyone out there burning their own VPC chips?

Rob_O
 

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Rob_O

Werent you running a Lexus SC300 or a 2jz-ge motor? If that is the case i have been advised to use the MK3 chip for the 550cc injectors and i plan on running the 720cc injectors for mine. Then instead of a GCC you should use an S-AFC because of the greater versatility of tuning the fuel. If you are running a 2jz-ge that is what i was advised to do if not then disregard this.

Later
 

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Formerly jza8shwoff
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Ok, I figured out how to use the little arrows to scroll down on that page and no listing for single turbo/stock injectors.
Yes, there is no chip for single turbo with stock injectors. Ideally the single turbo upgrades are designed for the power out levels where upgraded injectors are needed. When my supra was to4r and stock injectors, I used the stock twin/stock injector chip with the upgraded fuel pump and gcc to fine tune it...ran fine under 1.0kg/cm2 of boost until I got all the parts ready for the injector upgrade.

I guess at this point about all I can do is try whatever stock injector chip I don't have and hope it's better since the GCC will probably not have enough range to use the stock injectors with a 680 chip
Im lost here...you have a 680chip? but no 680 injectors? or do you have a stock chip but have a single turbo?

Let me know...ill help how I can.
 
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Discussion Starter #9
Brett:
Plan "A" was to do a turbolexus. Lack of a suitable car for the swap, wierd timing and the general odd way the universe works put me behind the wheel of a TT supra. I'm not going to bitch about it

Will:
Stock injectors, small single turbo. I ripped open the VPC and found it was in fact the AT chip. Maybe I'll try the 5 speed chip to see if it works any better for me because as it is now the fuel curve kinda sucks

Rob_O
 

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Hey Rob

Yeah as soon as i posted that i scrolled up and red about the Twin Sequential and knew that you werent talking 2JZ-GE language hehe. But a TT is better anyway. Good luck with your tuning there i hope you find what you are looking for.

Later
 

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Formerly jza8shwoff
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Rob,

The 5spd chip is worth a try, it will work fine with an AT. What kind of issues are you having with the current fuel curve. You have a GCC?


My friend was going to do the turbo lexus too..got the 5spd SC300 and a supra front clip all together too! Ohwells
 
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Discussion Starter #12
Jza8shwoff said:
Rob,

What kind of issues are you having with the current fuel curve. You have a GCC?
To sum up...

8 PSI, car runs lean... This happens whether I am running on wastegate boost only (boost controller off) or when the turbo is starting to spool and the car hasn't reached that magical point where the world comes rushing at you

18 PSI, car runs way rich. The FJO display only goes as low as 10.0, that's where it stayed for most of my WOT runs. By cranking the GCC to full negative across the board I could get the wideband reading in the mid 10's but then my low boost numbers got even higher

This problem is related to boost pressure, not RPM. I *think* it's because the stock injector chip is dumping as much fuel at possible at high boost because it's expecting the stock turbos to be superheating the air and it's trying to keep the engine alive.

The simple solution for this is to put in the big injectors and use the right chip but that's not exactly a simple (or cheap) solution, is it?

Rob_O
 
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