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Y7 To Y8 - How Do I Wire Vtec?

Discussion in 'ECU's, Electronics, and Tuning' started by foe-doe-ownin, Mar 1, 2003.

  1. foe-doe-ownin

    foe-doe-ownin Junior Member

    Likes Received:
    Mar 1, 2003
    I have 1997 Civic LX and i'm swapping a the Y7 head for Y8 head and i have it all put together but i cant figure out how to repin my Y7 harness for vtec.
    I also have the Y8 harness but i was told that i couldnt use it. Can i use the Y8 harness or do i have to repin my Y7 harness for the vtec solenoid, and the knock sensor?? Anybody have a diagram for this?? I will appreciate any help i can get, ive searched everywhere and it seems like no one has done this swap!!! :(
  2. pissedoffsol

    pissedoffsol RETIRED

    Likes Received:
    Sep 28, 2002
    Retirement Home
    this is an old write up from a mailing list i'm on- HTH

    below is the small writeup ive done for a mini-me swap...
    word of warning.. if the y8 head is a 96-98 and the y8 intake manifold is a 99 or 00 you will need to plug up the injector breather vents (i used permatex) or else you will have a major intake manifold leak.

    Here are the parts you will need:
    y8 head / intake manifold / throttle body / ecu etc.. basicly everything
    head up from the y8

    you will need to get a knock sensor since the y8 ecu expects a knock sensor
    and y7s didnt come with them, i would try to find one used since from honda
    they are around $150 new, there is a port this screws into on the back of
    the block right above the oil filter near the top of the block (its pre
    threaded). you will want to do this and run a wire for it before you put
    your y8 head/manifold on since its near impossible to get to.

    as far as wiring there are 6 wires to deal with:
    1 for knock sensor (1 pin, must be added see above)
    2 for vtec pressure switch (2 pins)
    1 for vtec solinoid (1 pin on usually green plug)
    2 for idle air control valve (canister hangs off back of y8 manifold near
    throttle body with 2 pins)

    you can either try to move the wires in your y7 harness or just run new ones
    (you can feed them through the boot under the battery holder), since I
    couldnt figure out how to remove the pins from the harness and relocate them
    without destroying the plug or pins i decided to just run new wires. this
    way you can just plug your y7 ecu back into the harness later on if needed
    without redoing the wiring again.

    4 wires will need to go inside of the car to the ecu, 2 are connected to
    things in the engine bay

    in engine bay wires:
    -one of the pins of the IAC valve, goes to the middle pin on the y7 iac
    valve connector, the y7 has a 3 pin connector the y8 has a 2 pin, the other
    pin from the y8 iac will run to the ecu (see below)
    -one of the pins of the vtec pressure switch needs to goto a good ground,
    the other pin runs to the ecu (see below)

    from what i can tell it doesnt mater which pin on those two connectors goes
    to the engine bay connection (above) or ecu connection (below)

    in ecu wires:
    here is the pinout for the 96-98 ecu's

    -the wire from the knock sensor will goto pin 6 (KS) on plug D/16p
    -the wire from the vtec pressure switch will goto pin 15 (VTM) on plug C/31p
    -the wire from the vtec solenoid will goto pin 8 (VTSOL) on plug A/32p
    -the wire from the iac valve will goto pin 12 (IACV) on plug A/32p

    i soldered the wires to the pin connections in the ecu (notched a hole in
    the ecu to run the wires into it)

    other than the wiring there isnt much to the swap, you just remove the y7
    head, put a new headgasket down then put on the y8 head. just make sure to
    follow the procedures in a maintenance book (haynes manual recommended).

    if you are going to use the y8 exhaust manifold/cat you will need to extend
    the wires on the second O2 sensor and then get your exhaust modified to mat
    up to the cat (dx exhaust at least on the sedans will go to far forward and
    about 10" needs to be cut off for the ex cat to fit under the car)
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