Dead Cyl(No.5)?

Discussion in 'Technical' started by CHILI, May 25, 2014.

  1. CHILI

    CHILI Indestructable Target

    I am currently unable to diagnose the loss of Cylinder 5(Drivers side rear).
    I have followed all of the step-by-step Fault-finding processes without a clear indication of the root cause.
    All Coil Packs replaced,
    New spark plugs,
    new Injector Plugs.
    All plugs firing outside of engine, Injectors(other than No.5) "clicking" when CAS spun by hand.
    All this leads me to suspect the Wiring Harness to No.5 and/or the No.5 Injector.
    Alzheimer's/stupidity/advancing senility has me unsure exactly how the CAS triggers BOTH the Plugs/Ignition AND the Injectors(all attempts to decipher the Factory W/Shop Manual Wiring Diagram has left me borderline suicidal).
    Does the single "click", when manually spinning the CAS Shaft, switch power to BOTH Plug Coil & Injector of a specific Cylinder?
    Any understandable information will be greatly received as I am not able to isolate whether the issue is a dead injector or a dead Ignition Lead(or both).
    P.S.
    I'm scheduled to commit Harri-Kiri sometime later this weekend(so an early response would be welcome).:confused::eek::zlove:
     
  2. Shane001

    Shane001 Well-Known Member

    Check the easiest option first, test the wiring from the no 5 injector connector back to the ecu for continuity.
     
  3. 90TTZ

    90TTZ Back From The Dead

    Hey Mate,
    The order of the coil and the injector doing their thing will not happen at the same time, hence the 4 cycles of the engine (Otto Thermodynamic cycle).

    You have mentioned below that #5 injector is not clicking so to me that is where the problem lies. Disconnecting all other injector connectors then verifying if it is working is the sure way of doing it. Unless you can get your hands on a Noid Light, then put a multimeter onto both pins of the injector connector and spin the CAS and you should see the voltage move a bit. If not then the issue is between the connector and the ECU or the ECU itself. If you are getting a voltage when you spin the CAS then likely the injector has failed. You can verify this by placing #5 injector connector on the next nearest injector and repeating the process.

    Unfortunately #5 is the PITA of all of them to diagnose being under the fuel pulsation dampner.

     
  4. CHILI

    CHILI Indestructable Target

    Thanks guys(I had reached that point where I was "second-guessing" myself into a state of utter confusion).
    I have just lengthened the injector lead on No.5, so as to be able to reach a couple of other injectors. I am yet to summon enough energy/conviction to give it a further test.
    Will the ECU Harness Connectors still be the same as the WSM Wiring diagram(given that I am running a Microtech LT4S)?
    I didn't take part in the installation, so I'm not certain.
     
  5. SuperZ

    SuperZ Resident Z lunatic

    There are air connections near no5 that if are loose will emulate the cylinder not firing regardless of all tests that confirm you have spark, injectors and fuel working correctly

    Happened to me once before, so just check you have no air leaks before you strip everything and then question everything and go completely insane.

    Good luck
    JC
     
  6. syntax_X

    syntax_X Zed Head

    Well your almost there.

    Definitely get your hands on a Noid, and not the kind that steals pizzas!

    If its not working steal a ground from another injector and try again.
    Still not lighting the noid? Get a multimeter and check continuity on no.5 signal wire,from injector connector to ecu with ecu unplugged.
    Also check sig is isolated from ground while your there

    Does the problem injector click when you have a known working plug on it. Ie plug 3 on injector 5.
     
  7. BLACK BEAST

    BLACK BEAST SLICKTOP TT R-SPEC

    I had this problem on the NA ,Couldn't diagnose it
    turned out to be the PTU


    .
     
  8. sandeep

    sandeep Active Member

    measure resistance of the injector on #5 using a multimeter. I think you are looking for somewhere around the 12-14ohm across the two pins for a healthy injector.
     
  9. tassuperkart

    tassuperkart Its a lie I tell you!

    PTU is on the ignition side. his issue is an injector not firing.
    I use a 12v supply on one side of the injector pins and quickly ground the other. If the injector clicks, the issue is in the wiring.
    Do it very briefly. The injector will still have some fuel pressure against it and holding the injector open will just flood that cylinder with fuel. I just flick the wire over the pin. it wont hurt the injector.

    Next, disconnect the ECU plugs. All of them.

    Ignition ON and check +ive side wiring to the injector. Test light is best. Multimeters can lie with dodgey connections.
    You should have +12 on one pin and light the test light. Other pin goes back to ECU.

    If you have +12v present at the injector plug then jump between the pins on the injector plug, paper clip/ bit of wire.. whatever works, check the injector wire for that cylinder at the ecu plug with a test light.

    You can do a final sanity check by reconnecting the injector plug, and quickly grounding the #5 injector wire at the ECU plug. The injector should click.

    E
     
  10. michaelZ

    michaelZ New Member

    The FSM has all details for checking injector Circuit.

    See page EF & EC-141 in the FSM for all details to assist in checking the Injector circuit.

    The ECU fires each injector by grounding one terminal of the injector. The other injector terminal is permanently connected to the positive of the battery. As I and others found out the 12V is always on one of the injector connector terminals regardless of the ignition switch position.

    The ECU also fires the coil packs but via the PTU. Two separate circuits.

    Good luck

    MichaelZ
     
  11. stumagoo

    stumagoo Active Member

    Just to add another method to check your injector (because three are plenty above) I personally take the plug off a known working injector hook it to the fauly one and spin the cas, if the injector clicks then chances are its the wiring (or even the ecu driver) you can take the wiring from the faulty injector and test it on another working injector as well to verify
     
  12. CHILI

    CHILI Indestructable Target

    Thanks guys.
    Your numerous suggestions and advice are extremely appreciated.
    After a good nights sleep and time to re-think, I feel I am in the right frame of mind to attack this again(hopefully with better results this time).
    I'll let you all know what finally occurs in this ongoing saga.:zlove:
     
  13. jamersss

    jamersss Member

    I had the same problem on my NA except it was cylinder 4.
    Combination of a bad wiring loom and bad ECU.

    Try switching the injector connector from another cylinder to cylinder 5 and see if it fires.
     
  14. CHILI

    CHILI Indestructable Target

    After further swearing & cursing, it would seem that the Wiring Loom is the culprit.
    Not being an Auto Electrician, I am open to some suggestions(of an Electrical nature, of course).
    How would you electrical guru's run new wiring to this cylinder/injector?
     
  15. SuperZ

    SuperZ Resident Z lunatic

    Are you able to test it at various points to narrow down where the problem is - it may be easier to replace the culprit section than running a whole new wire throughout the loom as that is a massive job and there is no easy way (as you probably already know or suspect)

    Have you touched the ECU or PTU recently - sometimes the connector can not fix all the pins properly and may need reseating (it can also help to use a electrical contact cleaner when reseating the connectors) They are also a good place to start testing line integrity

    Glad you narrowed it down - keep your sanity in the meantime!

    JC
     
  16. Shane001

    Shane001 Well-Known Member

    I wouldn't even attempt to repair the loom. The wiring on these 20yr old cars is near falling apart lol.

    I'd either replace the loom with a new loom, or just cut out the existing faulty wires at the ecu connector (allow at least 10cm from the actual connector) and the injector connector, and run two new wires separately and connect them up. Not ideal but with a bit of thought could be done neatly. Use some shrink wrap to keep the two wires together along the length and find a grommet on the firewall behind the engine to pass them through.
     
  17. SuperZ

    SuperZ Resident Z lunatic


    True - but even replacing the loom is a big job (and expensive) - there is no easy solution here - regardless he needs to confirm where the culprit section is first though before repairing
     
  18. Vader

    Vader Just another guy

    You won't be able to heat shrink the new wires to your existing loom. Go to Bunnings and buy the smallest cable ties they have. Then go to the auto store and buy high temperature electrical tape (in black).

    What you do is use Heatshrink to hold the 2 new wires together. If the new wires are 2 metres long, you won't need two metres, maybe about 20cm's. What you do is cut about a dozen pieces (or more) of appropriately sized heatshrink into pieces about 2mm wide. Thread your wires through these little loops and space them evenly along your 2 lengths. Then shrink them down to hold them together.

    Use the aforementioned cable ties to hold your two new wires to the existing loom at main junctures (basically just to stop it looping and to keep it running exactly parallel to the normal wiring).

    Alternatively, you could use short pieces of electrical tape every so often - the choice is yours.

    Use the tape to wrap your 2 new wires onto the existing loom so that you don't see any new wires. You don't absolutely need the cable ties/short tape pieces, but if you do, you will make the job easier.

    You will get a very professional looking finish if you follow these steps.
     
  19. Mitch

    Mitch Has one gear: GO

    I killed 5 PTU's costing between $50 and $250 a pop before I traced my electrical issue.
    My PTU's would last max 100km before getting too hot, melting or rendering themselves inoperable. So expense is not really a concern if reliability is desired.

    I replaced everything from the spark plugs to the ECU... including the loom. I believe the root cause was a bad coil pack in my case (although they all checked out OK with the resistance check).

    While a loom is a pain to install, DIY is relatively easy- the hardest part is removing the dash (which for those seasoned professionals amongst us, is not that difficult).
    The way i see a new (or near new) loom, is that it's cheap insurance for long term electrical issues. The loom I pulled off the car was well and truly cooked- the wiring can go hard and brittle after 20 years in a hot engine bay.
     
  20. zx299

    zx299 Well-Known Member

    Been there, done that.......

    I've had intermittent electrical problems 'up the whazoo' on the zeds and they are an absolute PITA to isolate.

    You appear to have narrowed it down to #5 injector and/or harness, so that makes life a bit easier........ unplug your injector connector and you should have 12v @ one of your injector connector terminals, replace the connector on the injector and you should also have 12v @ terminal 105 on your oem ecu connector (I'm assuming your a/m ecu piggybacks the oem connector).

    If you have continuity up to this point, you need to check the wire between the piggyback on terminal 105 and your a/m ecu. If everything checks out to here, your probable fault is with the grounding trigger in your a/m ecu.

    If you get here without isolating a fault, drop me a PM and I'll see what I can do to save you from "doing your head in" :eek:
     

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