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Missing - New spark, leads, coil, DFI - ideas?

Discussion in 'VY Holden Commodore (2002 - 2004)' started by Stramec, Feb 21, 2019.

  1. Stramec

    Stramec New Member

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    Hi All

    So my VY has decided to start missing and juddering. Assumed it was a dodgy spark plug, as they were due to be replaced, put in new sparks and new leads. Same problem.

    After reading this fine forum I tested the coils and found the 1 & 4 coil had no spark arching on it. So thought super easy quick replacement of coil. Same problem.

    Must be the DFI is shot. Just replaced that this morning, left the 1 & 4 leads off, and the coil sparked, put them back on, started the engine... Same problem.

    Took the leads off no spark arching on the 1 & 4 coil. As the problem is remaining constant either something is frazzling the DFI almost immediately, or it's being caused elsewhere.

    So now I'm at a bit of a loss. The engine starts ok, it judders a lot, especially under load. The other 4 cylinders seem to be working fine. So from my brief knowledge I don't think the CAS can be screwed.

    I have a Tech2 and that is showing no error codes, I'll try the paper clip test, just as a hail Mary.

    I cleaned the connector to the DFI, looks ok.

    The only other thing is intermittently I'll get a dashboard alert that there is a fuel gauge error and I should contact the dealer. - I don't see how this could be related to one coil not sparking, but it's there just in case.

    Would greatly appreciate some suggestions as to what to try next.
    Cheers
     
  2. _R_J_K_

    _R_J_K_ Well-Known Member

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    Did you chase the DFI loom back to see if any of it was freyed or damaged? Does the plug look in okay condition?

    I know you bought a new coil, but just to eliminate the new one being faulty too does the miss change cylinders if you swap the coils around?

    Also unlikely, but it might also be worth taking the rocker cover on that bank off to see if there's a cam issue (very unlikely as all other cylinders work) or anything wrong with the rockers, push rods, or valve springs. If you take all the spark plug out and turn it by hand it should be pretty obvious if anything's up.
     
    Last edited: Feb 21, 2019
  3. losh1971

    losh1971 Well-Known Member

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    Try replacing it with another coil pack
    Even if you just try switching around the coil packs.
     
  4. Stramec

    Stramec New Member

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    Hi - I tried that, the working coil fails in the 1&4 position, and the non working one fires in the 2&5, so I think the coil packs are ok, something further upstream, causing a rick.
     
  5. Stramec

    Stramec New Member

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    Thanks for the tip, will embrace that tomorrow, had a cursory glance at the loom, didn't seem too bad. Does each coil pack have it's own wire for a firing signal? That would certainly make sense as to why it's just that one position.

    Moved the coils about, the problem stayed in the same place, so think coils are fine. Can't believe I'd get two dud DFIs in the same spot, so going to guess that is ok. I'll try taking off the rocker and cranking it over without the sparks, if nothing obvious looks wrong with the loom.

    Cheers
     
  6. _R_J_K_

    _R_J_K_ Well-Known Member

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    Something to that effect, yes. Do the plugs end up getting covered in petrol? Just ruling out the injectors not firing.
     
  7. Stramec

    Stramec New Member

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    I think you are right, that it may be the injectors.
    I traced the wire loom nothing obviously out of place. Then I checked the injectors. The resistance across them all was the same, and the live current on the connector was steady, as was the pulse signal with the engine running on the earth wire. So I think the electrics to the injectors are all fine, however the two spark plugs from the misfiring coil, were bone dry.

    So I guess now my question is, is it feasible that a faulty injector would cause the ECU to shut off the associated coil?
     
  8. _R_J_K_

    _R_J_K_ Well-Known Member

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    Doubt it, plus if the ECU knew an injector was faulty it would probably throw a code.

    I don't really know what that means for you as it seems unlikely two injectors would die (but not impossible), but as a litmus test I would take all the leads off and crank it a few times and compare the plugs from the firing cylinders to the missing cylinders for petrol. If that gives you some info, I guess the next PITA step after that is to move the faulty injectors to different cylinders and see if they do it in different cylinders too (at least you don't have to put the upper manifold on to do this). That should be pretty conclusive.

    Nothing ended up being wrong under the rocker cover?
     
  9. Stramec

    Stramec New Member

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    Hi All
    Just for future reference, I fell foul of a 2nd DFI failing in exactly the same way as the first one! I dismissed it as being possible, can't say I even understand the underlying cause. But that is what happened.

    Initial DFI failed on one coil.
    Bought new DFI.
    Same coil still didn't fire.
    Went and bought another new DFI from Repco, slapped it in, and worked like a charm. (touch wood)

    Thanks to _R_J_K_ & losh1971 for taking the time to offer some help. Was greatly appreciated.
     
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  10. immortality

    immortality Home of the smoky breakfast Bacon! Staff Member

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    Been there...

    A faulty coil can kill the dfi (this happened to me).

    You can test the dfi module by removing all the coils and putting a test light across the 2 pins for each coil and cranking the motor.

    These days I only use genuine coils and dfi modules if at all possible.

    Good to hear you got it sorted and it's always good when the OP updates the thread with a positive outcome/solution :cool:
     
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  11. 87VLCALAIS

    87VLCALAIS Member

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    My VY S manual started missing just after I started it today. Middle of the day start, first start of the day, off to work. It misfired a couple of times then ran OK. I wondered what the cause might have been and dismissed it as perhaps a bit of water in the fuel. Less than 1 km later it stopped dead, rev counter showed zero. I rolled to a stop on the side of the road and tried to started it. The engine turned over OK but it wouldn't go.

    I rang the local mechanic and was told could be engine management computer, crank angle sensor, or the module below the coil packs, (I guess he was referring to the DFI). Nothing they could fix on the side of the road. I'd need to get it towed.

    I had a quick look under the bonnet in case I could see anything obvious. No such luck. I was about to arrange to get it towed and needed to move it a few feet to move away from a driveway I was close to. I was going to crank it on the starter to move it, to my surprise it started. I drove it back home, it didn't misfire once, but I wasn't risking it and was able to borrow a car to get to work.

    The car has done a bit over 380,000 km. I've had it since 20,000km. I've not replaced anything on the engine except plugs, leads, rocker cover gaskets, water pump, oil/air filters etc.

    I'm looking for hints on where to start, DFI? crank angle sensor? computer?

    To me the relevant bits of information are the misfire shortly before the complete failure, no rev counter, coming back to life after a short period. Which of the three items is likely to give those symptoms?

    Are there any simple tests I can do on any of the suspect items?

    Thanks in advance.
     
  12. losh1971

    losh1971 Well-Known Member

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    Scan for codes. Since it died, a code for either the DFI or CAS should be logged. Only issue you might have is the DFI code may come up as CAS. But yeah start with a scan.
     
  13. 87VLCALAIS

    87VLCALAIS Member

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    Thanks for the reply.

    I'm assuming a Tech 2 is needed for the scan. I don't have access to one of those. :(

    Then again it seems it may still give me a bum steer anyway (CAS fault code for DFI fault)
     
  14. losh1971

    losh1971 Well-Known Member

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    N
    It can but it may not. In reality to solve the problem a scan is needed. I believe some SCA stores scan PCMs for around 20 bucks. It will most likely be one or the other.

    Given the mileage on the vehicle and if neither of those parts have been replaced prior then probably start with the CAS as they are only about $55 at Repco, even cheaper on eBay. Just be sure to buy Delphi or Fuel Miser.
     
    Last edited: Apr 19, 2019
  15. 87VLCALAIS

    87VLCALAIS Member

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    Thanks for the help. Got SCA to run a scan. No fault codes came up. Beforehand I checked the plug connection of the DFI. Contacts were in good condition.

    So it's either wait till it faults again or start changing parts. On your recommendation I'll most likely start with the Crank Angle sensor. I'm not sure I have a breaker bar nor socket suitable to take off the harmonic balancer nor the tool for tightening it. Any trick or tips on that job. I may have to look at getting a mechanic to do it.
     
  16. losh1971

    losh1971 Well-Known Member

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    Its probably all of 40mins if that, if a mech does the the CAS. I need a crank seal replaced on my bus and don't have the puller so will probably just pay to have it done. Have a chat to your mech before you order parts he might have better advice. But given the mileage I would be surprised if the CAS is not going to fail at some point, not too far off regardless.
     

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