Connect O2 sensor when using a Juicebox?

Discussion in 'Technical' started by skybluestu, Nov 2, 2011.

  1. Hello one and all,

    I've recently had a TwoBros Juicebox Pro fitted to my Ninja 650R, should the O2 sensor still be connected to the exhaust bung or would it override the Juicebox? I'm having an Arrow slip-on fitted tomorrow so wondering whether I should ask them to not connect the O2 sensor?

    Thanks in advance
  2. Ive never used the Juice Box Pro but imagine it should come with pretty clear installation instructions? Though if the Juice Box is designed for the US model Ninja 650R that bike does not have an O2 sensor, in which case the instructions might not be correct for your bike...
    I had the old Juice Box on my old ER6n and it did NOT require the removal of the exhaust sensor. I'm tempted to guess the same if true of the Juice Box Pro.
  3. How did the install go? Typically these "piggyback" FI modules work best with the stock O2 sensor removed/disconnected. If it is not, then the ECU will try to go into closed-loop mode at certain RPM/throttle openings and try to adjust the mix to its pre-programmed O2 % setpoint. Effectively nixing out your post-ECU map adjustment in the closed-loop ranges.

    I know my PowerCommander III for the FJR and the PCV for the FZ1 both came with an O2 sensor "fake out" plug so that the bike did not throw a CEL (Check Engine Light) error. So I don't think there is any danger in removing the O2 sensor as the ECU will just default into open loop and let the Juicebox do its thing without interference.
  4. After reading the advice from Tony and also on a few other forums I decided to keep the O2 sensor connected when I had the Arrow pipe installed. It does seem more responsive with a smoother flow all through the rev range but there is some slight popping/backfiring on deceleration, I thought the juicebox was supposed to prevent that?

    ***EDIT*** Just read about backfiring during deceleration and many bikes with the stock pipe removed do this and is nothing to worry about.
  5. True that it won't hurt anything, but it sure is irritating. The backfire is due to a few different things and a Juicebox or Powercommander alone typically will not fix it. Some people claim to have reduced it by adding fuel in the zero throttle column but I have my doubts. Mainly because the main culprit for the backfire is programmed into the factory ECU as an emissions requirement for cutting the fuel under certain throttle positions and RPM. This is a US Federal EPA and EU requirement and no modern ECU controlled bike is exempt. Adding fuel to a piggyback module will not work in this case because the fuel injection is TURNED OFF at the source. You could add 100% extra fuel to the map and it would do nothing.

    What happens is the fuel is cut at say 6000 RPM at zero throttle to reduce emissions and then the ECU turns it back on at 4500 RPM and "re-wets" the hot and dry combustion chambers with fuel. That's where you get the loud BANG on decel. The other way backfire or burbling happens is from the AIS (air injection system) that is supposed to assist in burning unburned fuel in the exhaust ports and assisting the catalyst in being more efficient. Not sure about the Ninja, but most bikes can have the system plugged at the airbox or have the entire system stripped off by installing AIS block-off plates on the heads or valve cover.
  6. Yes, what Feejer says is accurate. A properly tuned fuel injection module will help reduce, but will not eliminate after-fire.

    Plugging or removing the PAIR valve (also called Clean Air valve) will also help reduce afterfire.

    The PAIR valve is an emissions device designed to introduce air from the airbox into the exhaust manifold to increase the efficiency of the catalytic converter. It has no effect on performance.

    If stock exhaust has been replaced with aftermarket there is no longer a catalytic converter so the PAIR valve no longer serves any purpose. It will continue to put air into the exhaust which will increase the amount of afterfire. Afterfire will not damage engine or exhaust. (Well, I have seen some glass pack mufflers lose their packing as a result of excessive afterfire, but that's not an issue for most pipes).

    The pair valve is the same on Kawasaki EX650 (ER6n/Ninja 650R) and KLE650 Versys:

    PAIR valve plugged with silicone caps.

    Airbox breather outlet plugged.

    Exhaust intake plugged.

    A view from the airbox to the PAIR valve after plugging both and removing the hose.

    Ride On!

  7. Thanks guys, much appreciated!
  8. Hi sorry to revive an old thread but I'm having the same issue...I've recently installed a PCV and today received my yosh TRC-D slipon...I've disconnected the O2 sensor and would prefer not to have a bung welded on my flash looking new pipe...

    So can I run the bike with the sensor unplugged? I know it throws an FI light, but is that the extent of it? is it going to run in limp I need a sensor eliminator kit? If so where can I get one in Thailand...

    are there any DIY garage hacks I can perform such as jumping wires or such like?

    2013 versys
  9. Ebay 20 bucks.

    There are varying degrees of limp home mode & the two I have experienced are triggering the FI warning light by disconnecting the 02 sensor & removing the secondary throttle flap causing the secondary throttle position sensor to be out of alignment. Both these FI light violations cause the ignition timing map to freeze on idle, so no ignition advance. The bike feels flat & slightly underpowered by this least intrusive of the limp home modes.

    In my opinion you really need to fit an 02 sensor eliminator, this will trick your ecu into running it's richest map & a produce a consistent mapping curve for PCV to piggyback from. Your 02 sensor will fight your PCV & try and lean off any map that is to rich at certain rpm's to "pass emission testing".

    Block off your PAIR valve either with a block off plate on the cylinder or a marble or silicon in the hose stopping clean air from getting to the head which causes popping in the exhaust to burn unburnt fuel for emissions again.

    You should have zero decel popping om a well tuned efi bike with generously rich mapping! 90% of bikes round my way cough & pop all the time with only slip-on exhaust fitted & I instantly can hear they will run badly & will be easily beaten in a race.
  10. Thanks Joe...I did a lot of research last today I blocked the pair valve and did the vacuum line mod.

    I learned of a trick to make the ECU never run in "closed loop" mode...from what I understand the ECu will switch to Closed Loop mode whenever you are at constant throttle...such as when your cruising at a constant speed and I understand it this is the only time the o2 sensor is being used by the ECU then and at Idle(once it's warmed up) So the trick is to stop the ECU from switching to CL mode and only run in "Open Loop" mode as the american bikes without o2 sensors do...evidently the American bikes do not suffer the "surging" and jerky throttle at low rpm because of this.

    So the procedure is to turn on the key and let the fuel line prime...then turn off the key and hold the start button and then while holding the start button turn the key on...the bike fires up instantly and it creates an error in the ECU as it hasn't been allowed to run it's boot up diagnostics and reverts to the default this mode it will never switch to Closed loop mode thereby rendering the o2 sensor irrelevant.

    So I tried it today...I ran the bike normally and it seemed to run fine, but the FI light was on the whole time I ran it that way...then I stopped on the road and shut the bike off and performed the new start procedure and the FI light went off and didn't come back on again until I turned the bike off at home and restarted it normally again.

    So I think I've found the solution. I'm running the bike with the o2 sensor removed and unplugged and it's very nice...beautiful 1st gear power wheelies, the bike comes up smooth and predictable...I'm using the yosh slip on map from Dynojet and it feels real strong...just a couple of slight hesitations in the power band at around 8-9000 I'll experiment with a few maps and see what works best.

    thanks for your help.


    Wow what a difference a map I switched to the EU version GPR slip on with airbox snorkles removed and stock airfilter...

    wow what a now pulls strong right from 3000rpm all the way to dips, no hesitation and a vibration I had at 5000 is gone as well...what a map.

    just to let anyone reading this know...

    2013 versys
    Power commander 5
    Yoshimura TRC-D Carbon slip on
    secondary throttle butterflies removed
    pair valve blocked (with a cap from a whiteboard marker ;)
    airbox snorkles removed
    vacuum hose mod
    O2 sensor unplugged and removed( no FI light if you follow the start procedure above)

    What a's a whole new bike!!

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