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VR v6 all 6 spark plugs carboned

Discussion in 'VR - VS Holden Commodore (1993 - 1997)' started by pete30nz, Apr 21, 2020.

  1. pete30nz

    pete30nz Active Member

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    Hi people

    Spare cas, spare dfi and coil packs set replaced. New spark leads. Spark plugs and oxygen sensor replaced new about 1000kms or less ago.

    Was doing some work on the car, had the car running for short times and a couple of road tests for no further than 1km.

    Car was at home and started running on less cylinders. I checked and cleaned spark plugs and the oxygen sensor which were all black.
    I do have new valley gaskets to replace in the next few days if all goes well. Would valley gaskets be a symptom?

    What else should i check people?

    Pete
     
  2. losh1971

    losh1971 Well-Known Member

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    Might be a faulty O2 sensor. I had a brand new one that was faulty from factory.
     
  3. pete30nz

    pete30nz Active Member

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    Cheers for your reply losh1971, I guess I'll Google how to check oxygen sensor with multi meter?

    Pete
     
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  4. losh1971

    losh1971 Well-Known Member

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    I think you hit them with a map torch and test the resistance with different heats applied.
     
  5. _R_J_K_

    _R_J_K_ Well-Known Member

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    While they still shouldn't foul up too noticeably, short tests while the car is cold aren't a real good indicator as the ECU will be dumping more fuel than usual into the engine to get it to temp. You really need to look at them after a drive where the car has been at operating temp for (IDK) like 10 or 15 minutes at a minimum maybe.

    Does it run right now? The missing is likely to have caused them to foul up if it's injecting fuel and not combusting, then it intermittently combusts when there's heaps of fuel in the chamber which means the mix is rich fouling the plugs. What's the part number on the spark plugs?
     
    Last edited: Apr 22, 2020
  6. pete30nz

    pete30nz Active Member

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    Hi rjk,

    The plug part number is ngkr bpr6efs 15
    I'll clean the plugs and the oxygen sensor again shortly and take it for a drive.
    I'm guessing it's the fouling that's making the car start missing /running rough.
    I'm sure if I went to start it now that itit will run, but it would be running rough

    Pete
     
    Last edited: Apr 22, 2020
  7. _R_J_K_

    _R_J_K_ Well-Known Member

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    A lot of the time it's a bit of viscous a cycle. The plugs foul for some reason (leaky injector, combustion issues, misfire), then in turn the fouing makes the initial problem worse via more misfire or whatever.

    In response to your initial post, valley typically gaskets won't do this, usually they just leak oil into the coolant when they go. Are all the plugs fouled or just one side? VN-VR all use bank injection so if the plugs are all fouled on one side it's kind of telling. Other places I'd start looking are around injectors and the fuel pressure regulator, possibly the map sensor, also busted coolant temp sensor is one that would cause a lot of issues like this..
     
    Last edited: Apr 22, 2020
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  8. pete30nz

    pete30nz Active Member

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    It's all 6 spark plugs. I'll take a photo of the plugs soon when I get to them.
    I could try another spare set of injectors.
    How to clean the map sensor?
    I have a recollection that my iat sensor could be faulty maybe?
    I'll check the ECU temp sensor under the alternator also, I think I have a spare some where.

    Pete
     
  9. _R_J_K_

    _R_J_K_ Well-Known Member

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    Given it's all 6 plugs, super unlikely to be injectors themselves. Trace the wiring loom for them back and see if they're frayed anywhere though. MAP is usually just a total replacement, you can't really clean them like you can with a MAF (MAP isn't a really common failure though, just something to be aware of).

    Have you pulled any codes from the car?
     
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  10. pete30nz

    pete30nz Active Member

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    Hey,
    I bridged the pins and only get code 12 which is a pass.
    About to go pull the plugs shortly and check the oxy sensor
     
  11. pete30nz

    pete30nz Active Member

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    Here are the spark plugs I just pulled, smells a bit gassy or oily - can't decide.
    Will do oxy sensor tomorrow
     

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    Last edited: Apr 22, 2020
  12. pete30nz

    pete30nz Active Member

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    Hey, I found this in another thread, not to sure if its my cause, but some thing to check the seals of.

    : if there is oil on the threads , may be rocker covers leaking a bit of oil and leaking into the recess in cylinder head where the spark plugs screw in . if the threads are dry and the tips of the plugs are oily , then you may have mechanical problems , worn piston rings , valve stem seals , too much oil in sump .....etc .

    Any other input welcome

    Pete
     
  13. vc commodore

    vc commodore Well-Known Member

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    With oil on the thread...If it's leaking from the rocker cover, you can generally see a line of oil, running from the base of the rocker cover to the spark plug hole....If you can't see this line, the issue is internal....worn valve stem seals (which is generally the issue) or worn piston rings...
     
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  14. pete30nz

    pete30nz Active Member

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    Hi VC, thanks for the reply.
    So I'm guessing all the valve stem seals wear down at the same time.
    What would I need to do to replace these.
    Edit: I found out how to just now

    Cheers Pete
     
    Last edited: Apr 23, 2020
  15. losh1971

    losh1971 Well-Known Member

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    Sometimes the guides wear, which doesn't help either. Some cars don't always have valve stem seals if the guides are still nice and tight. I rebuilt an old 75 engine years ago and it never had seals. The guides were pretty fucked though and it burnt oil even after rings and a hone. But I didn't want to spend money on a Repco change over head, so slapped it back on.

    Glazed bores will cause oil burn as well.
     
    Last edited: Apr 23, 2020
  16. pete30nz

    pete30nz Active Member

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    I'm hoping its some thing small like valve stem seals. Do these engines have valve guides as well. I'm eager to learn, have pulled my old VR v6 engine down, but all I've done internal work wise is valleys, balance shaft and hydraulic lifters.

    Pete
     
  17. losh1971

    losh1971 Well-Known Member

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    Eco is pretty similar in a lot of ways to the Buick. It will have guides. The valves wouldn't stay in place otherwise. I'm pretty sure you can change the valve stem seals without removing the heads. You might be able to check the guides at the same time, but it's heads off to replace them.
     
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  18. pete30nz

    pete30nz Active Member

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    Yes they look similar. But still haven't done any internals on any engine apart from the VR engine
     
  19. losh1971

    losh1971 Well-Known Member

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    Internals are reasonably similar. They improved some aspects of the V6 when they went to the Eco.
     
  20. losh1971

    losh1971 Well-Known Member

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    I have an idea that the Buick heads will actually bolt on to an Eco but that would be as far as you would get.
     

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