Plenum/coil pack earths

Discussion in 'Z32 Technical' started by waZed, May 17, 2018.

  1. waZed

    waZed Member

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    Hey guys, I know there has been a few threads on this before but unfortunately I can't seem to find my issue.

    Did a full plenum pull, rewired all coil packs, new battery harness, hard-wired s2 ptu, and relocated.

    Car started, but I forgot to put the earth's on the plenum back on, and popped the ptu! Dang it. Lost cylinders 1 and 2.


    Got another ptu, connected the grounds (cleaned threads and mounting points) checked that I had the right pins going to the right places, and tried again. This time I had cyls 1 2 and 3 out. Now I don't know if this s2 was a confirmed working one - I didn't meter it out beforehand. Wish I did.

    So I double checked I hadn't mixed cyl 1 ground and ptu, rechecked all the pins going between plugs and ptu connectors.

    Spent up big for a brand new s2. Now I don't want to blow this one..

    Measuring resistance for grounds is the only thing I can see weird.
    Every middle pin has 12v, every left pin goes to ptu and every right pin goes to ground.

    However cyls 1 2 and 3 have 8 ohms to ground, but 4 5 6 have 16 ohms to ground... Weird?

    I've checked the main earth cable, Def strapped to block, and top transmission bolt. The 3 separate earth cables I can find on the plenum are all clean and tight.

    However, as seen in this photo (will upload in a sec) , I have 2 earth cables doubled up x2, plus one fat earth. The two doubled up are on passenger side, by cyl6, and the fat one is above cyl 5.

    Bad connections between coil pack plug earth pin and these.

    Where do all the coil pack earth leads go? They are either soldered in the main harness somewhere or I have lost an earth cable...?

    I took a pic, I'll jump online and host it so I can share it


    If you have any ideas, Let me know! Really don't want to blow up the nice new ptu hah
     
  2. waZed

    waZed Member

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    Hope the attached file works..
     

    Attached Files:

  3. beaver

    beaver southern zeds

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    All those earths are engine earths, as apposed to body earths, I always attach the p/side earths to the bolt hole at the back edge of the upper intake plenum or any 10mm bolt that screws into the engine in that vicinity . The drivers side earth can be attached to any 10mm bolt that screws onto the engine in that are, theres a couple within reach. I also have a heaver gauge wire straight of the battery onto the block. See the manual EL 132.
     
  4. geron

    geron National Petroleum Equipm

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    The Coil pack connectors have two earths. One comes from the 'ignition coil relay' through the coil pack connectors and to the PTU and the other comes from the engine ground to the coil pack connectors and again to the PTU. All coil packs share the same earths in parallel.
    If you are worried about earthing, check the problem coil connector pins against the other good working coil pack connectors for earth continuity. You will soon find out which pins are earth and which have continuity or not. If on the problem cylinders you don't get earth continuity on two of the pins, there's a wiring issue.

    If you do get earth continuity on the connectors, then earthing is not the problem here.
    I'd be checking the rest of the wiring and if that's OK, then process of elimination says PTU.

    Please refer to diagram below, it will help you:
    upload_2018-5-17_21-55-27.png
     
  5. geron

    geron National Petroleum Equipm

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    Let me know if you need a copy of this wiring diagram and I will send it to you via PM. This is rather small to look at.
     
  6. East Coast Z

    East Coast Z Well-Known Member

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    Re: Earth wires.
    Disconnect all the coil pack connectors.
    Check the resistance between each earth pin in the six connectors & write down the resistance values.
    Check between No.1 & No.2, then No.1 & No.3 repeating through to No.6.
    Disconnect the earth wiring at the induction manifold & retest the resistance of each connector from No.1 through to No.6 to the ring terminal that bolts to the manifold.
     

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