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L322 2002 v8 misfire

Discussion in 'Range Rover' started by Ruby Range, Jan 18, 2021.

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  1. Ruby Range

    Ruby Range Well-Known Member

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    Hi all I have a slight missfire on my 2002 v8 which i cannot seem to track down. Checked all coils and all ok. Cannot find a vacuum leak and checked pressure for pcv ( taking oil filler cap off) all good. Took the rear plug out on drivers side and found piñon the tip!!. Cleaned off as thought I may have dipped it somehow when putting in but still a problem. Runs fine on cold start and when above 1000rpm but still have bad fuel consumption. Beginning to suspect a bloody head gasket!! Any other ideas!! No management light on or code!!
     
  2. kermit_rr

    kermit_rr Green Member Full Member

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    Have you checked the O2 sensors are working? What about the MAF?
     
  3. Henry_b

    Henry_b Penguin

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    O2 sensors not switching, Maf sensor buggered.

    the M62 is a fussy unit, and likes everything perfect.
     
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  4. Ruby Range

    Ruby Range Well-Known Member

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    Maf sensor I believe is good as all gear changes are good and I know that the maf also causes this issue but will have a code reader done on Wednesday and someone has mentioned the o2 sensor. My biggest fear is the oil returning on the plug when I remove it again
     
  5. Mark Piercy

    Mark Piercy Well fumbled member.... Full Member

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    A compression test if in doubt of the gasket/rings or cylinders.
    While on live data and engine running, watch the o2 sensor and spray a tiny amount of butane or a similar gas and watch the o2 sensors behavior change.
    O2 sensor 1 bank 1 or bank 2. This determines the engines fuel mixture. O2 sensor 2 bank 1 bank 2 watches the cats behavior.
    If you introduce a separate fuel through the air intake it'll change the behavior of the o2 sensors and they will react by adjusting the fuel intake.
    If they don't react one or both are duff.
    The black plug could be a valve stem, valve seal or rings on that particular cylinder (internal oil leak).
    If the whole bank of plugs are black, say Bank 1,it could be down to an o2 or maf sensor.
    Just because a sensor gives feed back it could still be under performing and having manufacturers specs can help to varify that.
     
  6. kermit_rr

    kermit_rr Green Member Full Member

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    this gives you an idea what a bad/failing o2 sensor looks like, slow/weak response...
     
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  7. biketeacherdave

    biketeacherdave Well-Known Member

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    Are you saying you have oil on the plug electrode?? Or just oil on the plug ?? If your cam cover oil seals is leaking they fill the plug holes up with oil and cause a miss fire
     
  8. myfirstl322

    myfirstl322 Well-Known Member Full Member

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    I had a misfire after doing the cam cover gaskets, turned out to be a bent fuel injector electrical pin.

    Not helped by the proper instruction of yanking the injector bank OFF and also the hefty pushing back ON.

    (Oil in plug wells is common, fixable with new inner and outer cam cover gaskets, AND a functioning PCV valve)

    Oh boy, the flashbacks.:eek:
     
    Last edited: Jan 19, 2021
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  9. Ruby Range

    Ruby Range Well-Known Member

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    thanks for the reply I am going to check the O2 sensors once I’ve changed the plugs and checked that the one plug that was oiled up is now dry
     
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  10. Ruby Range

    Ruby Range Well-Known Member

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    Ok so new plugs in no oil on top so all good. New plugs in and still a misfire. Plugged in my snap on diagnostics and came up with tank vent valve and p0443. Cleared all faults. and spent an hour pulling vent lines and things I have no idea about !!!. Start car up and ran ok for about 2 mins and now although a miss fire nothing as bad as before and now no faults just the tank vent. 2 questions really. Firstly could this actually cause a misfire and secondly where the hell is it !!!
     
  11. Mark Piercy

    Mark Piercy Well fumbled member.... Full Member

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    Who's fuel are you using @Ruby Range? Intermarche and eleclerc is not the best and do you do a lot of shorty journey's?
     
  12. Ruby Range

    Ruby Range Well-Known Member

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    Yes quite a few short journeys but every third fill up I use premium fuel like texaco super. Will do a 30 mile round trip tomorrow and then see what faults it throws up. Anyone tell me where the fuel vent valve and purge valve are !!!
     
  13. Mark Piercy

    Mark Piercy Well fumbled member.... Full Member

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  14. JUKE179r

    JUKE179r Well-Known Member Full Member

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    Got any fault codes?
     
  15. dubbleRR

    dubbleRR Well-Known Member

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    DOO ..on here had a misfire ,he striped the wiring loom to the changed ,maf cps coils leads ,then it started using water :eek:,,,,it was a head gasket in the end :( ,Have you tried a compression test ,are you losing water .any back pressure in header tank ...Hope its a simple fix...
     
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