PVCX with wideband | Victory Motorcycles: Motorcycle Forums

PVCX with wideband

Discussion in 'Victory Cross Country' started by IndyVictory, Jul 23, 2020.

  1. IndyVictory

    IndyVictory Active Member

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    Been running bunch of logs refining my old tune and getting tuned in areas I never would put into narrowband and all is going well.

    One thing that is a little concerning is that the front is consistently on the richer side and the rear is consistently lean. It varies of course how far they stray from target but I just found it odd that they are out of balance like that. Nothing extremely far off though.
     
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  2. Bikesofbrads

    Bikesofbrads Member

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    Keep plugging away so U can school the next person.
     
  3. IndyVictory

    IndyVictory Active Member

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    There is no schooling anyone. You can't buy a PVCX anymore. I just thought it odd the cylinders out of balance but I'll fix that soon. Checked and couldn't find any exhaust leak that was my first thought with the rear being on the lean side. Apparently Polaris just sucks at factory tuning. I can't see any reason for emissions to have cylinders out of balance.
     
  4. Bikesofbrads

    Bikesofbrads Member

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    Is beyond my scope of knowledge so I can’t offer any help @ all but I wish U the best of luck & am sure U WILL figure it out. Hopefully they’ll bring the pvcx for victory back, Is nice when has options for ecu tunings other than Maximus. Competition is always good esp when we R those 1’s that win. Good luck!!!!!
     
  5. md2420

    md2420 Well-Known Member

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    I don’t know anything, so consider this “asking for a friend”.

    Wouldn’t the rear jug naturally be hotter/leaner than the front jug since it doesn’t get as much air flow?

    when I had mine dynod (PCV), the tuner attacked each cylinder separately. Maps between front and rear jugs are different.
     
  6. IndyVictory

    IndyVictory Active Member

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    Well even at cold start the rear is leaner than the front. That is why I suspected possibly having an exhaust leak but I can't find any leak. Heat itself would not create a lean condition. Lean will run hotter though.
     
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  7. IndyVictory

    IndyVictory Active Member

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    Looking at another Victory tune someone sent me couple years ago. Same deal. Rear was running lean while front was just a little rich.
    Theirs was a 2016 Magnum and mine is a 2012 CCT. I guess stupid tuning didn't change over the years. At least now I know I'm not totally crazy. Stock tunes apparently set up to run lean on the rear and I still don't see any logic in doing that.
     
  8. Bikesofbrads

    Bikesofbrads Member

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    Yea that’s weird but I’m sure there is a logical explanation for it. I’m surprised this thread hasn’t gotten more attention, is tons of knowledgeable people around here.
     
  9. mande

    mande Member

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    @IndiVictory
    I observe the behaviour in a more differentiated way.

    I have (unfortunately) no wideband. I still have an autotune. Unfortunately it does not fit to the PVCX.

    Nevertheless. In my stockmap (Hammer 8-ball 2013) the Fuel Comp Front table is richer in the lowend areas than the Fuel Comp Rear. In the middle and upper ranges it is rather the other way round.

    All my tunefiles (total over 300) the behaviour is rather the other way round. But Fuel Comp Front and Rear are more balanced.

    With stockmaps and tunefiles from friends I see different behaviour.

    How does your bike behave when you talk about out of balance? How does the bike feel?
     
  10. IndyVictory

    IndyVictory Active Member

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    It rides fine. I'm looking at about 1.0 difference in AFR between front and rear. So say I'm targeting 13 front might be 12.5 with rear at 13.5. It's worst down low RPM where rear is supposed to be hitting 13 and it's closer to 15.

    The difference is not always that dramatic it's mainly under 3k RPM. I just find it weird.

    I was cruise control down interstate 75 MPH yesterday a did a short log of that and it's almost perfect both cylinders in sync hitting very close to target 13. Numbers nearly identical if I remember right both slightly rich like 13.2. It's like that for much of the upper RPM range both are well balanced on fuel.
     
  11. waterhog

    waterhog Well-Known Member

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    Based on your observations, O2 sensors don’t seem to be the problem but it may not hurt to switch the front/rear sensors and check that readings don’t change. O2 sensor calibration and accuracy is an issue unto its own although with new sensors it shouldn’t be a problem.
     
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  12. IndyVictory

    IndyVictory Active Member

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    That's a good idea. Easy enough to swap them around and see how it reads.
     
  13. TwoManyXS1Bs

    TwoManyXS1Bs Active Member

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    Been cogitatin' on your issue, and had an idea, until I read that you're reporting that the AFRs are different.

    So, this probably wouldn't apply, but I'll stick it in here anyway.

    If the AFRs front/rear match, but the fueling is different front/rear, it *could* indicate a mismatch in VEs.
    An intake leak could cause that, or misbalanced exhaust piping, or throttle plates out of sync.

    On vintage multi-cylinder bikes, carb synchronization is just as important and common as setting points timing, and changing oil.
    There's strong language in the Victory service manuals to *NOT* tamper with the throttle body setscrews.
    I can understand that for the master idle stop screw, not so sure about the rear cylinder synchronizing screw.

    Consider this pic of the throttle body right side, with its stop screws and interconnecting link.
    20200703-ThrottleBody02.jpg

    On older, high-mileage bikes, I can visualize the pivots of the interconnecting link getting worn, allowing the rear cylinder to slightly lag behind the front cylinder. Tuning on the Maximus, with equal target AFRs front/rear, the front cylinder would pull more air/fuel, and the fueling tables should reveal that. After about 10-15% throttle the differences would be negligible.

    Been studying this for awhile, as I can feel/hear a slight cylinder imbalance on my Vegas at light cruise, one cylinder pulling a little harder than the other, until about 20-25% throttle. I sense that I need to do a carb sync. But, I'm not seeing a significant pattern of fueling mismatch in my Maximus fueling tables. Nothing in the manual but warnings of severe bodily harm from some enforcing agency if those screws are tampered.

    I haven't found any threads/posts that touch on this "synchronizing" subject, and wonder if it could be a worthwhile pursuit.

    Continuing in contemplation...
     
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  14. IndyVictory

    IndyVictory Active Member

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    I looked at my old tune files with narrowband. Same thing. Rear was just a little lean with front little rich. As you say it's only at the lower range just like I'm seeing in mine. They run nearly identical above 3k. So maybe they just programmed them that way for reasons unbeknownst to us.
    I'm not too concerned about it I'm just fixing it and moving on.
    The overall engine temperature reported by ECU still runs about same but the exhaust temperature is notably cooler and so am I with the rear properly running the correct AFR.

    Now I do wonder if this imbalance exists on all models. Popular addition of timing wheel correcting possible power loss under 3k with slightly imbalanced fuel delivery.

    Timing will be my next experiment but not really sure what pinging sounds like. Careful experimentation with slight increases.
     
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  15. Bikesofbrads

    Bikesofbrads Member

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    Any news after switching the O2’s around?
     

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