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Wheel Whore
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2,317 Posts
Discussion Starter #1
My car is running pretty lean. I have yet to buy a wideband as I had just got the car back together from a buildup. It is currently running bone stock fuel with no by-pass mods (will do asap), and no 12v mod. I was advised not to do the 12v mod for some reason.

The turbo on the car is an sp63 .81 on an HKS header. And I am running the 1 bar spring out of the GT gate with no boost controller. I cannot boost past 1 bar.

I thought this would be safe, and my vpc settings, and gcc settings are set to zero as well.

When I checked my plugs they are black around the ring and pure white on the tip. Sp I am running lean as hell right now.

I turned up the gcc settings up all the way across the board, run the car and check the plugs and they are still white. So I play with the gain knob and turn it to +9, I am still getting pure white on my tips. Even driving it for 10 miles on zero boost I still have the same white results.

My questions are, is 1, I do not have my 2nd O2 hooked up. It is completely disconnected. Will this cause my car to lean out this bad? What else could it be? I am currently putting together a fuel system but I'm just annoyed because its only at 1 bar. Any input would greatly be appreciated thanks.
 

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Professional OT Bum
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654 Posts
I would not drive it until I figured out what was wroung, why blow a motor when half assing a job? get the fuel pump and play it safe
 

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1,421 Posts
I could be wrong, but I don't think you're supposed to touch anything on the VPC, and only 4K and above on the GCC. If you try to mess w/ the closed loop settings, the computer will compensate across the board, and you will be lean, IIRC.
 

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And I hate to say it, but do a search and you'll come up w/ something. I recall reading a long thread about this. You should also get a wideband to tune, using the trial and error method is risky on a turbo car, especially these cars. You won't blow a head gasket, you'll hurt a piston. Good luck
 

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Boost Junkie
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12,616 Posts
Get a wideband. If you are OBD1 you have the dreaded lean problem that many of us have had. Try an OBDII computer or a fuel system. You can also get an aftermarket regulator and turn up the pressure.

Steve K.
 

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Wheel Whore
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2,317 Posts
Discussion Starter #7
I don't think turning the knobs up will make any differences. For now I will try the bypass line, new filter, and dual pumps just to keep it safe. For now I am happy with one bar and at the time I didn't think I wouldn't have leaning issues on low boost. But maybe the flow numbers on an sp63 on 1 bar might be like running stock twins on high boost? Anyways thanks for replys good or bad.
 
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