Cor…inexcusable, totally gratuitous. and unnecessary nonsense but what V pins!
Yes, I meant if you wanted it to run in closed loop, but if you unplug the lambda sensor, it will force open loop mode.
Running the sensors disconnected won’t do them any good as they need the heater elements to prevent damage from hot gases. Hence complete removal in my case.
No, the lambda sensor doesn’t work until it’s hot enough, the electrical heater is to heat it up to working temp as quick as possible during the first few minutes after a cold start, so the ECU can start running closed loop as soon as possible, thereafter, the exhaust gas is hot enough to heat it. So can’t see how leaving it in will cause any damage.
I’ll be removing them as they are in a hot corrosive fluid outwith designed parameters whilst not wired and operational. Possibly over rich causing carbon fouling of interstices. In a box they are less likely to suffer mech damage. Replacement value of £100 each is another reason to replace with £5 caps.
Edit: twa nuts in a baggie arrived today…
OK I’m butting out, but will still be following I want to know how this turns out.
Velly intleresting, but not stoopid.
From the logic the lamda sensor is only there because legislation says so, and no other reason.
That’s the case for every modern vehicle!!
Bottom line, anyway ~ but, at the same time can run open-loop, which is what happens if lambda sensor goes AWOL.
Nobody’s mentioned the cat yet, does this bike have a cat?
Yup. However its not fitted permanently.
Brodie & V7.jpg
Of course removing and blanking doesn’t get to the nub of the thread - why does the V7 exhibit this stalling in the closed loop area intermittently?
only issue with all this is that the latest mot regs say that the emissions control system must be present and correctly working. At the moment bikes are not subject to emissions testing but it may come at some point
I shall worry about that when it happens.
Me too.
Ah!!
Last week I managed, through a gouty haze of pain, to get the V7 outside and cobbled together the GuzziDiag system. Appears to maybe indicate some thing inconclusive is possibly wrong with the right hand lambda sensor. Once a bit more mobile I will take it to a chasp who tests these things and find out if its OK or not. Might try a reset on two parts of the system whose names skip my mind at the moment or maybe not. It all depends on something I vaguely have in mind.
Gout, yikes …
Yes, apols if I have been somewhat brusque but was fair rattling with chemicals of late…seems sorted now. Me and my Allopurinol.
I was wondering that too. I’ve had a good look round underneath and I can’t see it unless it is integral to the silencer (unlikely). Does anybody know if these bikes have them and if so where it is please?
Been reading this thread with interest…
I have a V7 II brand spanking new, and it runs perfectly EXCEPT for part-throttle cruising between 2k-4k RPM, where it hunts and hesitates like it’s running too lean. Shame, because it spoils what is otherwise a very sweet running engine.
I’m keen to fix this problem. Even worse it’s downright dangerous if I transition from closed (or almost closed) throttle to part open during a manoeuvre, as the engine bogs down then suddenly snaps into life - this happens no matter how gentle you are with the throttle application.
Cruising gently through towns with a gentle throttle opening is almost impossible - Sometimes I have to alternate between throttle on/throttle off, because a constant fractional opening just makes it hunt.
From what I’ve read and learnt, the ECU modulates the AFR and looks for a corresponding rich/lean indication from the O2 sensors. The idea is the average AFR is correct, which means part of the time it’s running too rich/too lean, which I presume is the cause of the hunting. I’ve also read the ECU goes into open loop mode above 4k RPM, so the problem only occurs in the low rev range.
My bike’s under warranty so I have to be careful, and I’ll mention this issue at the 1st service, but I’m interested to hear whether the ECU would complain if the Lambda sensors are disconnected/removed.
I’d like to hope the default fuelling with sensors disconnected errs towards rich, which would make the bike much more drivable.
I’d really appreciate if anyone’s able to confirm:
a) Would the MIL light come on, or would a DTC be raised if I disconnect the lambda sensors?
b) Has anyone measured the AFR with lambdas disconnected, to confirm it’s within acceptable limits?
Yours hopefully…
Pete.
I’ve been running with them disconnected for about 1500 miles now with no ill effects apart from slightly lumpy low rev running, but still driveable around town. My mpg figures have not changed (about 60 mpg), so I assume the mixture setting is about right… Starting cold and hot is fine. Mine is coming up three years old, so out of warranty, but as yours is in warranty I’d suggest not waiting for the first service and get it sorted now. My symptoms were slightly different to yours (read the thread for details) but have cleared up since running with disconnected lambda sensors. On this thread we’ve come to the conclusion that the lambda sensors are the problem since running disconnected makes the problem go away, but it might be more nuanced than that - maybe an interaction between the ecu and the sensors for instance. I don’t live anywhere near a dealer and don’t want to pay dealer rates for them to investigate, but if yours is a similar problem and it is under warranty you can get it fixed for free. It would then be useful to report back to the forum as to how the dealer fixed it.
Good Luck!
This is called ‘closed-loop’ and my understanding of it is to lean off the fuel as much as possible without leaving any oxygen in the exhaust, which means too lean. In this context ‘too lean’ means combustion chamber will be very hot with possible damage to piston crowns etc. This is why it has to be a computer monitored feedback system (hence ‘closed-loop’).
The basic AFR is done by the fuelling map.
The hunting is simply due to it running lean, not so much to damage components by overheating but still makes it run like crap. Like it’s about to run out of petrol.
Disabling the O2 sensor (lambda sensor) forces open-loop fuelling which is by fuelling map only.
I was sure cats for motorbikes are indeed inside the silencers, 'least I’m pretty sure my Piaggio has one like that, it’s a bluddy big silencer and weighs a ton, just for a ‘poxy’ little 330cc single cylinder!
Thanks for the replies Peter and Mike H, it seems we all have the same basic problem. I’m pretty sure it’s not a fault with my bike, just a “characteristic” caused by excessive emissions control (thanks, EU!).
Talking to friends with other modern bikes, they all seem to have similar problems to varying degrees - even on quite expensive bikes.
And I notice other forums report very similar symptoms with the V7, even to the extent of stalling until thoroughly warmed up (mine’s OK if you’re gentle with the throttle when cold).
The good news appears to be that:
a) The ECU only operates in closed loop mode at light throttle settings and moderate engine revs. That’s the only time I experience any problems, so fiddling with the control loop could bring worthwhile improvements.
b) It’d be relatively easy to modify the signal fed back by the O2 sensors to fool the ECU into thinking the mixture is weaker than it actually is, thereby stopping it leaning out quite so much.
I see such devices are available (e.g. FatDuc O2 manipulator), but since electronics is my game I’m inclined to make a few measurements on the standard set-up and then devise a circuit to shift the operating point of the sensors. I’m hoping this will be enough to stop the ECU leaning out to the point where the engine falters and rattles the backlash in the transmission.
Now I know why dealers have suggested slipping the clutch at low speeds… But surely one thing a big old V twin should be good at is low speed running?!
I’ll report back any findings when I get around to tinkering.
BTW Mike: Yes the V7 silencers do contain a catalyst, which is why it’d be preferable to allow the ECU to run closed loop if possible.
Pete.
The Finebau Forge gizmo does the ‘tweaking’ of the O2 signal, http://finebauforge.com/