What's wrong with this cylinder? pic of spark plug | FerrariChat
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What's wrong with this cylinder? pic of spark plug

Discussion in 'Technical Q&A' started by luckydynes, Jun 30, 2007.

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  1. luckydynes

    luckydynes F1 Rookie

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    #1 luckydynes, Jun 30, 2007
    Last edited by a moderator: Sep 7, 2017
  2. luckydynes

    luckydynes F1 Rookie

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    #2 luckydynes, Jun 30, 2007
    Is it lean perhaps . . . dirty injector?

    I'm using an aftermarket efi with direct fire waste spark ignition . . . the other cylinder in the pair is the plug that's in the pic.

    I cleaned and swapped the plug with another hole yesterday and checked after a short test drive and it didn't look much different.

    It's got about 2-3 hours on it now.

    Thanks,

    Sean
     
  3. Steve King

    Steve King F1 Rookie

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    #3 Steve King, Jun 30, 2007
    Looks like it is running to lean.
     
  4. spiderseeker

    spiderseeker Formula 3

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    #4 spiderseeker, Jun 30, 2007
    Yes, looks like a little lean to me too. Keep an eye on that cylinder and you might try adding some good quality injector cleaner(Techron) in the tank . If it still has the old injectors, it might be time for a change. (to the improved brass style)
     
  5. luckydynes

    luckydynes F1 Rookie

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    #5 luckydynes, Jun 30, 2007
    Last edited by a moderator: Sep 7, 2017
    Thanks for the input.

    Looks like there's a lot less carbon on the piston in that cylinder also . . . looks like it got a little warm in there . . . plug from this hole did not look this way about 10 engine hours ago. About 20 engine hours ago I got the direct fire ignition working and dialed in more advance . .. checked the plugs back then and thought it was all okay. It's been a little warm out lately and I've been heavy with the right foot. It's number 1 cylinder on a 308 FYI.

    Checked engine compression and that was okay.

    So if it is lean on the one cylinder I'll probably swap the injector and check for any vacum leaks. It's also the last injector on the rail on that side and I just turned the rev limiter up to 8200 rpm . . . could be starving for fuel I guess . . . if swapping the injector doesn't do anything and I don't find any vacum leaks I'll look there also.

    Thanks,

    Sean
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  6. luckydynes

    luckydynes F1 Rookie

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    #6 luckydynes, Jun 30, 2007
    Thanks for the input . . . another vote for lean.

    They were brand new Ford motorsport injectors when I installed them during my efi conversion. Put about 40 hours on my old motor and about 170 hours on the new motor to date.

    I replaced the fuel filters 12 years ago when I first bought the car also . . . just continuing my thought about loosing fuel pressure causing lean condition.

    I have a wideband 02 sensor on that bank and it's not been showing anything weird but I don't know how the other 3 cylinders mask 1 if it's lean.

    Thanks,
     
  7. PAP 348

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    #7 PAP 348, Jun 30, 2007
    +1, I agree also, only a few days ago my brother and I serviced his work car and we found 1 plug in similar condition, we took the injectors to my mate who tested them and found one has a poor spray pattern indicating a restriction, we replaced the filters in the all injectors and them rested them, spray pattern was excellent, refitted them and replaced the plugs with new ones :)
     
  8. Spencer89

    Spencer89 Karting

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    #8 Spencer89, Jun 30, 2007
    As a rule, when the top of a pistion is cleaner than the others, it usually means that coolant is getting into that cylinder. Your spark plug in the photo also looks slightly cleaner and to have corrossion on the threads. A simple cooling system chemical block test would be a good thing to have done, to see if any exhaust gases showup in the coolant. A lean cylinder with advanced timing under hard acceleration will usually ping like crazy.
    Regards, Rick
     
  9. ferrariblue

    ferrariblue Formula Junior

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    #9 ferrariblue, Jun 30, 2007
    I've seen worse plugs under a lean condition. You said you dialed in more advance? Try retarding the ignition a bit. When engines get hot they don't like too much advance - have you noticed any pinging? When it is winter time you can program more advance to the ignition, without too many ill effects.

    CP
     
  10. mk e

    mk e F1 World Champ

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    #10 mk e, Jun 30, 2007
    It's a bit leaner than the others, but absolutely nothing to be concerned about. Just cruising about they should all be almost completely clean, I run mine quite a bit leaner than it looks like you are....it looks like you are around 13.5 or maybe 14, 14.7 at cruise and idle (if it will run smooth) is what your after. At low power, any imbalance anywhere can cause slight variations plug to plug.

    The real test is under power. Find a big hill, run up at WOT and at the top or redline, kill the ignition (still at WOT) and push the clutch. Now pull a few (or all) plugs and see what you have, they should be much dark tan. If you have a white one after that, you have a problem.
     
  11. luckydynes

    luckydynes F1 Rookie

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    #11 luckydynes, Jun 30, 2007
    Thanks all for the input.
     
  12. tatcat

    tatcat F1 World Champ
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    #12 tatcat, Jun 30, 2007
    have you checked your plug extender? a cracked extender may cause the spark to arc increaseing the resistence and making it burn hotter.
     
  13. No Doubt

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    #13 No Doubt, Jul 1, 2007
  14. luckydynes

    luckydynes F1 Rookie

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    #14 luckydynes, Jul 1, 2007
    Someone mentioned this too me also . . . I'm hoping it's not coolant related. If it is coolant I guess best case is it's leaking thru the intake manifold . . . I would think if it was the head gasket she'd be running hotter.

    I heard some pinging once or twice so maybe I'm a little close to the edge timing wise or the injector is inconsistent causing an intermittent lean condition and the pinging . . . at WOT my wideband shows around 12:1 but like I posted before I don't know if the other three cylinders would mask the lean one.

    Thanks,

    Sean
     
  15. luckydynes

    luckydynes F1 Rookie

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    #15 luckydynes, Jul 1, 2007
    Thanks, it's been hot lately so this might have something to do with it.
     
  16. luckydynes

    luckydynes F1 Rookie

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    #16 luckydynes, Jul 1, 2007
    Thanks for the reply Mark . . . I'd feel a lot better knowing the plug is getting like this NOT under full power.
     
  17. luckydynes

    luckydynes F1 Rookie

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    #17 luckydynes, Jul 1, 2007
    no plug extenders . . . got the motorcycle coil-on-plugs working :)
     
  18. luckydynes

    luckydynes F1 Rookie

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    #18 luckydynes, Jul 1, 2007
    Thanks and I reviewed that thread also.

    Another observation which you can't see on the plug but I hope is consistent with being lean: up inside the plug . .. on the I.D. of the metal portion it looked kind of "ashy" like it does on the end of the ring . . . consistent with lean or a little too much heat from too much timing?

    I'm running around 10.5:1 compression and have taken the timing all the way back up to 36 degrees . . . this might be too much now we're into the summer heat.

    It sounds like for the most part it's a minor problem if a problem at all . . . something must have changed though however minor because I'd been checking my plugs pretty frequently and they looked so consistent between cylinders . . . maybe the hot weather and too much advance creating the perfect storm in that cylinder.

    Thanks so much for all the feedback . . . will report back my findings.

    Sean
     
  19. eulk328

    eulk328 F1 Rookie

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    #19 eulk328, Jul 2, 2007
    If a plug extender has a crack which causes arcing you will not get a spark at the spark plug electrode and therefore it cannot burn hotter.

    Erich

     
  20. oss117

    oss117 F1 Rookie

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    #20 oss117, Jul 2, 2007
    Careful, because it is not only lean: it is also hotter.
    Also, 2 to 3 hours of use may not be enough to change the appearance of the plug enough to understand if the changes have been effective.
     
  21. mk e

    mk e F1 World Champ

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    #21 mk e, Jul 2, 2007
    12 is pretty rich for naturally aspirated, 13.2 is where peak hp should be...although if you are on the edge with compression, the extra fuel will generally let you run the timing higher and could make more hp....only the dyno will know for certain.

    and yes, the A/F you're seeing is an average...there is no substitute for doing a proper plug read, it never lies.
     
  22. luckydynes

    luckydynes F1 Rookie

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    #22 luckydynes, Jul 3, 2007
    I did I leak down with the engine cold . . . 7%

    did a leak down with the engine warm (oil 165 deg) . . . 4%

    did a leak down with the engine HOT (oil 210 deg) . . . 7% and bubbling thru the expansion tank.

    Fortunately it's the rear head . . . have it off in a bit.

    Sean
     
  23. mk e

    mk e F1 World Champ

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    #23 mk e, Jul 3, 2007

    I'm surprised. I have heard on some of the f-cars, a simple retorque works wonders, it might be worth a try.
     
  24. luckydynes

    luckydynes F1 Rookie

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    #24 luckydynes, Jul 3, 2007
    Last edited by a moderator: Sep 7, 2017

    I retorqued the heads at about 1000 miles/30 hours when the engine was hot and the nuts didn't move.

    I checked them this morning cold before pulling the head off and they didn't move. Was hoping I caught it soon enough so there's no metal loss in the area . . . . looks okay in pic . . . the leak was on the exhaust valve side of the combustion chamber . . . are the white chunks in the combustion chamber by-products of the temporary water injection or detonation that might of made the gasket go?

    You running stock head gaskets on your motor?

    Thanks,

    Sean
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  25. mk e

    mk e F1 World Champ

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    #25 mk e, Jul 3, 2007
    I think the chuncks are from the water....detonation almost always puts specks of metal on the spark plug.

    Yes, I'm running stock head gaskets on my engine, mines a QV though...I think the gasket is slightly different.
     

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