S2R 1000 hunting at constant trottle - Ducati Monster Forums: Ducati Monster Motorcycle Forum

harrievr · 07-10-2006, 10:15 AM

I have a problem with the ignition of my S2R 1000. When I try to drive at a constant speed and keep the trottle steady, for example at around 4000 rpm, the engine is hunting. It is only a very subtle hunt, but it is noticable that the rpm's go up and down very slightly every few seconds. This makes the ride restless and I find this very annoying. The funny thing is that when I unplug the O2 sensor, the problem is gone completely and the rpm is rock solid with a steady trottle.

Any suggestions on cause and solution? I would like to use the O2 sensor, but not if this is the consequence of it.

BryanS · 07-10-2006, 10:59 AM

I don't know that this is your problem, but I had that issue and my dealer diagnosed it as a bad TPS. Once it was replaced and the bike was tuned up it ran like a champ.

mflas · 07-10-2006, 08:08 PM

Same thing happens with my bike...I hate it. I already had the tps changed, because it shorted out. The bike still surges (hunts as you put it) at 4000 rpm with constant throttle in 1st, 2nd, and a little in 3rd. At higher gears it doesn't surge.

tpark · 07-10-2006, 08:22 PM

Me three.

800ducs · 07-10-2006, 09:53 PM

Me Five

I'm installing an Arrows full system shortly and hope it will sort it out.

TurboTim · 07-10-2006, 11:48 PM

Well if ya unplug the O2 and it runs good I think your on to something. What it sounds like is a lazy O2. Its taking to long for the O2 sensor to switch from rich to lean so the ECU is allways playing catch up. If you want me to explain in greater detail I would be glad too.

tpark · 07-11-2006, 12:56 AM

Please do explain. I've read elsewhere that the O2 sensor only comes in to play at low rpm's or when the engine's cold or something like that. Is that not the case?

opwierde · 07-11-2006, 01:51 AM

Quote:

Originally Posted by TurboTim

If you want me to explain in greater detail I would be glad too.

Yes please!

hiero · 07-11-2006, 08:09 AM

just fyi, brad black posted this yesterday about the closed loop system and operation (can be found here: http://www.ducatimonster.org/smf/ind...c,53079.0.html):

Quote:

Originally Posted by brad black

the closed loop bikes - s2r1000, 695, s4rs, sport classics, st3 - don't have the normal idle trimmer adjustment facility. you can try to adjust it, but it makes no difference. the closed loop system works up to 5 or 6,000 rpm and up to about 15 degree throttle i think. anything over that is open loop, so you can tune that area just as before.

if you try to tune the closed loop area the bike will 'retune' itself using the o2 sensor output to get back to where it wants to be. it retunes itself by looking at how much it has to richen or lean the mixture to get back to the desired switching rich/lean situation it aims for. it then stores that info in an adaption table, and uses that in conjunction with the fuel map for future reference. it's a constantly updated procedure whenever the bike is running closed loop. there are limits to how much it can go richer or leaner, and if it reaches the end of its allowed travel one way it will log a fault.

so the options are some sort of aftermarket add on box (pc3, dobeck, dimsport), a replacement dp ecu or a replacement aftermarket ecu, such as the u59.

so you can:

fit an add on box and not tune the closed loop area (pretty easy) or tune it and let the ecu retune itself as it wants too. i have run a dobeck on a sport 1000, using only the yellow pot and leaving the green zero.

fit an add on box and disconnect the o2 sensor and tune it as desired and don't worry about the closed loop thing at all. in this case you'd want to disconnect the battery for a few minutes to clear the adaption table before you tuned it.

run the u59 ecu, which ignores the o2 sensor and works as normal in open loop.

the dp ecu are also intended to be open loop i believe, but you actually have to disconnect the o2 sensor to stop the ecu getting stressed.

that's the tuning options as i understand it.

the new gen3 dobeck box has a closed loop manipulation function, but i haven't used that. the pc3 from any m1000 should work just fine, dynojet are just wacky about things they haven't tuned themselves. dynojet sell a pc3 for bmw that has a wide band sensor input that runs closed loop up to about 80% throttle or something like that. never tried one, but that may be available for ducatis in the future.

harrievr · 07-11-2006, 08:14 AM

TurboTim,

I am very interested in your explaination.

One additional point of info: I already have the O2 sensor changed for a new one. No change.