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VPC Questions

1000 Views 13 Replies 5 Participants Last post by  vntperformance
I recently installed the HKS VPC and Apex'i AFC combo into my car and I need to clear up some questions. The VPC came with the harness, in order to put in the AFC, I cut the YELLOW wire that went from the VPC and into the harness, then I put the AFC wires in between. Is that right, or was I supposed to cut the blue wire? Second, everytime I turn the steering wheel, my boost gauge shows vacuum going up towards -2 psi. Is that normal because the vacuum hoses are now tapped off to the same outlet? And will that affect my boost controller? Thanks for any replies.
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i have the same question, i have a vpc with apex afc, i dont know where to hook the airflow/pressure wire to. cutting the yellow wire comming out of the vpc is it right? i need to know. because my car wont run right , it studder bad with just the vpc only. yours do any studdering after the vpc is installed?
Here's the wiring setup for VPC + AFC.. Good Luck!

--------------------------------------------------------------------------------
ECU/stock wiring harness wires:

RPM wire (green, pin 58)
power (red, 31)
MAF signal (yellow, 66)
ground (black, 69)
throttle (grey, 43)

VPC wires:

MAF signal out (yellow)
Power (red)
Ground (black)
RPM signal in (white)

S-AFC wires:

RPM in (green)
Throttle in (grey)
MAF out (yellow)
MAF in (white)
Ground1 (brown)
Ground2 (black)
Power (red)

You splice the VPC and S-AFC ground and power wires
in the stock harness ground and power.

You splice the VPC and S-AFC RPM wires into the
stock harness RPM wire.

You splice the S-AFC throttle wire into the stock
harness throttle wire.

You connect the VPC MAF out wire to the S-AFC MAF in
wire.

You CUT the stock harness MAF wire and connect the
S-AFC MAF out wire to the side leading TO the ECU. Leave the other end insulated w/ black tape.
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thanks Aaron hope my car will be running good after i do this. do you have and studdering problem with the vpc when you install it? mine dont want to rev up missing bad, hope this will fix it .thanks again....sonny
From your description it sounds like you have the wires messed up for the "MAF" signal that the VPC/AFC sends to the ECU. Does it idle real rough, and blow a lot of black smoke? Thats what mine did when i had the wire wrong..

Now that i have it wired right, when i first start it after an ECU reset (unplug battery) it idles perfectly fine, but it does have a bad hesitation, until i drive it around for a little while, and the ECU learns how to work the with the VPC/AFC combo..
Aaron i got my car stright last night, start up and drive good, with a little hasitation when i try to get on it. my check engine came on though, i check it and code 31 (turbo pressure signal something like that) doid you have that problem?
No, i dont have any check engine lights..

What year is your car? OBDI or OBDII?
my car is a 94 obd 1, ive check it, its code 31
G
Mine hesitated for a little while till the comp learned/ i also moved the response know 2 clicks to to right clock wise and that seemed to help.... anyone know if you have to use the capacitor on the maf plug.. my check engine is already 0n so im not worried about it.... thanx KEvin..
nautica2o3,
Can't help you with the VPC, but in your first post you mentioned that your boost pressure changes when you turn the steering wheel. This happened with my car because I tee'd the vacuum source from the intake manifold where the power steering line hooks up. Try teeing off from a different vaccuum line.

Alan
If you are asking about the resistor, yes you need to use a 1200 ohm resistor in the MAF plug, or in the ECU harness..



Kevin Hornsby said:
Mine hesitated for a little while till the comp learned/ i also moved the response know 2 clicks to to right clock wise and that seemed to help.... anyone know if you have to use the capacitor on the maf plug.. my check engine is already 0n so im not worried about it.... thanx KEvin..
Aaron;

i know this is an old post, but the MAF Plug has several pins, which pins do we put the 1200 Resistor in?

thanks.
valT.
laurel,md
G
Hey rush racer I have the same Engie check light... I thought it might be my TPS sensor, but since it came on after installig VPC i thought i might hvae somethign to do with it...

did you find the fix??
vntperformance said:
Aaron;

i know this is an old post, but the MAF Plug has several pins, which pins do we put the 1200 Resistor in?

thanks.
valT.
laurel,md
Aaron,
i have the same exact problem as you had on yours, and originally mine was wired up the wrong way, and i rewired it according to your specs and the car is still doing the same thing......belching out black smoke, and running/idling like shit.

we swapped out the chips, and the actual pressure sensor, and the actual vpc unit..but the problem still persists.. Do you think it might be a stuck injector?

thanks.
val T.
laurel,md
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