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De-cat & O2 sensor eliminator plugs: opinions please.!

Discussion in 'Norton Motorcycles (Modern)' started by Deano, Sep 16, 2019.

  1. Deano

    Deano

    Joined:
    Jul 24, 2019
    Hi all,

    I know from looking on the forum that the issue of a lumpy/erratic idle & snatchy low speed pick up etc is one that many 961 owners have experienced. I would like to improve this aspect on my own 2014 961 & am considering going down the de-cat route with O2 sensor eliminator plugs. I'm not bothered about gaining any extra power & don't want an ECU re-map, I'm just trying to get a smoother idle & better low speed running.

    Are there any owners out there who've just done the de-cat & eliminator plugs who can advise as to whether or not this would improve matters? Or is this a pointless exercise without going for a a re-map as well? I'm not expecting the bike to purr like a Honda VFR750 but just to idle & pick up like a well set up twin on carbs would do. I'm guessing that just making the mixture a tiny bit richer may help matters as it's clearly running lean at low revs.

    Thanks in advance... :)
     
  2. TonyA

    TonyA

    Joined:
    Jan 16, 2015
    With a Euro 3 bike you shouldn't have any problems with the O2 eliminators . The Euro 4 were having the problems when they tried them. What exhaust system is on it now and what map ?
     
  3. TonyA

    TonyA

    Joined:
    Jan 16, 2015
    Decats do make the exhaust a bit louder . On both the short and long Norton free flow mufflers. I have never tried this with the stock quiet system. But as I say it won’t hurt to try and see. The main reason we tried using the O2 eliminator resistors was for a lean spot during low rpm cruising. If we were on the throttle hard then you wouldn’t notice it. They work for this without doubt. Some of us swear by them , and they are easy to remove and go back . If you have a 2014 then that’s my year too.
     
  4. Deano

    Deano

    Joined:
    Jul 24, 2019
    Sorry, forgot to mention the bike has the long louder pipes fitted & although I haven’t owned it from new, I have no reason to believe that it’s ever been re-mapped. So I assume it’s as it left the factory.

    As well as improving the idle & low speed running, I’d like to be able to return it all to standard if required should emissions ever become testable n the UK, or when/if I decide to sell it one day. The cats & stock silencers would be stored up in the loft... ;)
     
  5. iwilson

    iwilson VIP MEMBER

    Joined:
    Nov 6, 2015
    This isn’t going to help much practically speaking. But anyway... I've been looking into this problem over the winter. There are a few factors combining to cause the idle problem.

    • Charge stealing caused by both throttle bodies sharing the same idle air supply leading to the ECU seeing one cylinder lean and the other rich.
    • The ECU (all ECU’s), use a PID controller to achieve a target air fuel ratio (AFR). This is a closed loop system that uses measurements from the o2 sensor to apply a change to the fuel injectors - the resultant change in AFR is signaled by the o2 sensor and the loop begins again. But... if the algorithm used to decide the amount and rate of change is not correct the AFR will swing wildly leading to an erratic idle.
    • Unfortunately for a catalytic converter to work correctly it needs the AFR to swing from rich to lean. This requires the PID controller to be programmed to allow the AFR to swing more than if it was only focused on achieving a very narrow AFR range.
    My bike has achieved idle nirvana, due to removing the entire idle air assembly and blocking the tube that connects both throttle bodies. I have also disabled the o2 sensors (I have a programable version of the stock SCS ECU).

    The downside to this is no idle air control. The plus side is you discover that despite the best efforts of the factory to f@#k up this engine there beats a heart of gold. Once you remove the veneer of an awful design decision with regard to the throttle bodies the engine suddenly shows it will happily start and idle from cold 400rpm below the factory setting! Meaning once it’s warmed up it sits at 1,200rpm. This is a great example of less being more!

    Here’s the prove (yes, I’ve posted it before). My bike with no idle air control and the shared idle air pipe blocked.



    Unfortunately if you keep the o2 sensors once they’ve warmed up and the ECU switches to closed loop using the PID controller and o2 sensors I start to see an erratic idle as the PID controller starts to lose control. I’m confident it’s just a matter of adjusting the PID settings to eliminate the wild swings. But the only point in doing it would be to prove I can. Since no one here would benefit and Norton have shown no interest in sorting out these issues (despite the relative simplicity and low cost in doing so). Despite the above I enjoy figuring out these problems and promise I will present the complete answer in the next few months.

    I’d be so bold as to say if all owners bikes idled as well as my bike and had the same crankcase breathing system aka no oil filling up air boxes or ugly boxes trying to catch it they would have sold a few more bikes (guess what Norton, many prospective owners are probably turned off when they find this forum)!

    I’ll be presenting all of the above in a lot more detail when I’ve finished testing and documenting. The bike will be going back on the dyno in a few weeks for its final mapping session.

    Bottom line is in the modern era you are at the mercy of the factory, unless you replace the ECU with a programmable version and have a good understanding of EFI engines. If they made a change to the throttle body design most of your problems would go away.
     
    pingu-nz likes this.
  6. Deano

    Deano

    Joined:
    Jul 24, 2019
    I agree that the system as factory fitted could be better in an ideal world. But, as I understand it in the UK at least, the lean(ish) mixture at idle & low speed is to satisfy emissions requirements, albeit to the detriment of smooth running. In this respect I believe the factory’s hands are somewhat tied. All I’m seeking to achieve here is a slightly richer mixture up to about 2000rpm or so to ease the intermittent stalling & snatchiness at low revs. Perfect running is not expected, I’d have bought a Japanese multi cylinder bike if that was a deal breaker. I’m just after an improvement... :(
     
    jan nelder likes this.
  7. ntst8

    ntst8 VIP MEMBER

    Joined:
    Feb 14, 2004
    Good to know that you are still beavering away there Ian.
     
  8. iwilson

    iwilson VIP MEMBER

    Joined:
    Nov 6, 2015
    Emissions has nothing to do with the problems. Just bad design of the throttle bodies. There is a long thread I started about this. Yes, the engine like ALL internal combustion engines needs to run rich when cold, but it should meet its target once warm. As I mentioned (and proved), once you remove the mechanical design deficiencies you have a different engine. Unfortunately most people assume the factory engineers must know best and leave it there. That’s why I’ve documented and spent a large amount of money on commercial grade diagnostic equipment to validate my observations. That video was one of many that has been shared here or in some cases with the factory.

    Personally I couldn’t care, I don’t buy and sell. I’ll never sell my Norton so it’s worth is irrelevant. So I don’t mind riding it or trying to improve it. Same goes for the other Brit in my garage a Lotus Elise S1 - its Rover engine (118hp) could not be saved/reliability improved, but transplanting a tuned Honda k20a (260hp) engine turned it into a 911 beater!



    Sorry for the novel/rant blame it on a couple of Negroni’s! https://en.m.wikipedia.org/wiki/Negroni

    Not a huge amount of progress since you visited, but the landscaping is done! Actually that’s a lie, have completed a number of courses with hpacadamy.com well worth it if you’re able to do anything with the knowledge i.e. get inside the ECU. Lotus Club btw is doing a run up the Awhitu peninsula on Sunday, I’m taking the Norton you’re welcome to tag along.
     
  9. 2cups

    2cups

    Joined:
    Feb 8, 2018
    Hi Ian does removing the idle set up also help with mid range fuelling (juddering) I have decat and pipes plus remap and also a power commander fitted. Love the bike and it goes well just a small amount of juddering at a couple of cruising speeds. Great work you’ve been doing
     
  10. nopdog

    nopdog VIP MEMBER

    Joined:
    Apr 24, 2017
    Deano
    DO IT!!!!!!!!
     
  11. Deano

    Deano

    Joined:
    Jul 24, 2019
    Ian, thanks for all the good info & I fully acknowledge your excellent efforts in getting to the heart of this issue.

    I still believe that the requirement to meet emissions does have a contributory effect on the poor low speed running, however. There may well be flaws in the fundamental design, as you suggest, which only compound the issue. But IMHO the bike is clearly running too lean at low steady state engine speeds & that’s a function of the O2 sensor adjusting the air/fuel ratio in a closed loop. A slightly richer mixture would make the bike run a bit better in the lower part of the rev range. It certainly has on other air cooled single & twin cylinder bikes I’ve owned, where it was a simple case of adjusting the idle air screw or slide cutaway on the carburettor.! The good old days...

    As I say though, that’s not to disagree with your general assessment of the EFi system shortcomings in any way, which I have no doubt is correct.

    Many thanks for your help... :)
     
  12. BritTwit

    BritTwit VIP MEMBER

    Joined:
    Aug 25, 2009
    Right you are.
    I bet the new V4 and 650s don't use Jenvey throttle bodies with single air tubes.;)
    If Norton decide to continue 961 production, perhaps the MK3 version will have a proper Keihin, Bosch, or Magneti Marelli EFI system.
    This will unfortunately reduce the percentage of British components in the 961, but will make the 961 much easier to live with, and more attractive to prospective buyers.
     
  13. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009

    Interesting link to hpacademy. Thanks. I'll be taking some of those courses too. I have a good collection now of books on engine management and tuning, but I also like the way hpa presents the material.

    Ken
     
  14. Britfan60

    Britfan60

    Joined:
    Jan 5, 2014
    I found no earth shattering difference. Also, it used to take one press to start, idled at 2200 and settle at 1200. With the eliminators, I get intermittent LOW idle, 800, hiccups and catches itself before stalling and 2 to 3 starting attempts. Still got the vibes at 3700 and my mileage dropped from 44 mpg average to 40. I don't get the 2400 rpm anymore though. That's a plus. Sometimes 1800 but that's the IAM flange coming loose. I'm just happy as a pig in shit that its running and I'm not getting stuck.
     
  15. iwilson

    iwilson VIP MEMBER

    Joined:
    Nov 6, 2015
    As far as I'm aware motorbikes do not get tested for emissions in the UK when undergoing an MOT. The factory only has to get a pass mark as part of the process in getting type approval to sell the bike. Which is why people often permanently remove their catalytic converter on a bike but if you own a car you have to refit it for every MOT as cars do get emission tested. I think they stuffed up the throttle body design, didn't realise it - struggled to tune around the problem to get the engine to pass the relevant emissions regime. The end result is the unstable idle we see today. If you don't believe they could make that mistake then look at the oil in the airbox issue. It took forever for them to work out what was going on and multiple attempts at fixing it. Lets face it the fix is a band-aid and the bikes still come out of the factory with a nappy on (the plastic oil collection bottle). I mean what manufacturer ships a modern engine with a nappy strapped to it!

    It's not Jenvey's fault, Norton owns the design. Bizarrely it would be relatively easy to change the design to fix the problem, but for some reason they either don't believe it's the cause of half the problems or perhaps they would need to re-certify the package if they made the change. I have spoken with both Jenvey and Norton about the issue...

    I find myself in a position where my engine is essentially sorted, but I'm kind of intrigued to better understand the root cause of the problems many other owners have especially at idle. But it takes a huge amount of time, trying different things both with the software and hardware to the point I haven't bothered much over the last month or two - but I'm feeling the urge to finish the job.

    I believe that's because you still have the charge stealing going on at low rpm. Since I don't have a stock ECU anymore can anyone tell me if the bike throws a wobbly if you pull the plug off the IAC valve? If it doesn't then the best thing you can do is remove the whole assembly and block the shared pipe between the throttle bodies. As you can see by my video the result is a very un-Norton like idle!

    Ken the courses at HPA are well worth the cost, the information is presented well and I have to say it's a real eye opener in terms of the amount of work the ECU is doing and it's ability to control processes I had no idea were occurring to begin with! Who knew that amount of time a fuel injector takes to open when commanded to do so could make up an entire lesson!
     
    pingu-nz likes this.
  16. richard-7

    richard-7

    Joined:
    Feb 24, 2014
    Ive done far too much to help on this subject directly to the question. However, at one time I eliminated IAM and since upgrading to the omex ecu I put back the IAM and my bike runs incredibly perfect. So for those eliminating the IAM. You can achieve the same results but with cold start not an issue by upgrading to omex. I have a thread in making a bracket for those with single seat machines.

    Keep in mind I have gapless rings, major engine mods, de cat pipe, one07 wires, bosch everything, omex ecu conversation using norton patch cable, iridium plugs, o2 resistance plugs. 2014 SE.
     
  17. iwilson

    iwilson VIP MEMBER

    Joined:
    Nov 6, 2015
    That's really interesting Richard. So just to be clear, you've reinstalled the IAM and have not modified the throttle bodies i.e. the idle air is using the stock shared pipe? If that's the case it certainly contradicts my experiences! But in saying that if everything else is perfect the engine is certainly capable of idling ok in the stock configuration. Particularly if it doesn't spend a lot of time at idle where the rich mixture can foul the plug.

    I have the OMEX ECU lying around somewhere, but I know when it was installed things didn't really improve (I had the SC ECU to start with and Norton replaced it with an OMEX ECU when the dealer damaged the case) - in fact I actually had the bike dynoed when they fitted it to see if the map was any better power wise (about the same if I remember rightly).

    Glad to see you're enjoying the fruits of your labour!
     
    richard-7 likes this.
  18. iwilson

    iwilson VIP MEMBER

    Joined:
    Nov 6, 2015
    I wouldn't think so, once the throttle butterflies start to open they flow way more air than through the IAC valve. Hard to say without being there, has Power Commander looked at it? If it occurs like clockwork I'd put it on a dyno, would be simple to identify and fix it.
     
  19. TonyA

    TonyA

    Joined:
    Jan 16, 2015
    When he says judder , does he mean an odd vibration ?
     
  20. skidmark

    skidmark

    Joined:
    Nov 6, 2014
    "Are there any owners out there who've just done the de-cat & eliminator plugs who can advise as to whether or not this would improve matters? "
    Going back to the original question, yes I have just done the temp speed sensor, head temp, bosch coils and leads and the O2 eliminators along with the factory decat. In that order. Of that lot the O2 made the most difference to tick over and clean running. It does smell more though. Decat is a bit louder but not offensive.
     

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