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View Full Version : 999 Stutter between 3 and 4 thousand RPM ? 999



john
25.05.2006, 09:28 AM
I have a couple of times noticed my 999 developing not a misfire but a 'stutter', like a richness, between 3 and 4 thousand RPM. It did this the other day after washing it(?). It ran fine across and back to Hawick at the weekend. It started fine and I rode towards town noting the stutter - above 4,000 all seemed fine and clear revving. Got to the petrol station whereupon the engine revved to 2,000 without being asked. I waggled the throttle cables and it died back down and stalled. Restarted and it ticked over okay. Rode off and it felt like one cylinder faded but came back. Rode home with the stutter still present.

Last time it happened, just the stuttering, it seemed to smooth out by itself. I put it down to some degree having changed the front sprocket to a 14 which had moved normal running speed to a different rev range. But this can't be the case since it cleared.

My suspicions were aroused by it happening after washing the bike. Water in the intakes? Mind you I have ridden this and my 749 through torrential rain with no problems.

Sticky choke mechanism? Bad electrical contact? Anyone got any similar experience.

It is an 05 999s with the 102dB system and about 3,000 miles.

I am booked in for a service next week so if I can't find anything hopefully the dealer will, although intermittant things like this usually disappear the second the bike rolls over the threshold.

Freak
25.05.2006, 09:59 AM
Did the dealer set it up, a lot come out of the factory with fuelling issues usually resolved at the first service.

Could be something like coils and as you have said after it's be wet etc, the front coil was a known issue on early 749/999's as it's exposed to the elements, a quick grease of the o-ring seal and some silicon spray on the head should sort that.

As for the cables etc well that's not right and that could be the root cause of the issue, plus being potentially dangerous to boot.

Daft as it may seem but a lot of fuelling issues are resolved by using a power commander and set-up accordingly, the standard Ducati ECU doesn't seem that great to be honest, some bikes run fine some don't and have usually been resolved by doing this - more expense

Derek
25.05.2006, 10:00 AM
Since it has happened after washing the bike the likelihood is that it is caused by water ingress into an electrical connector associated with the injection system. I'm not familiar with the layout on the 999s but the on the ST4s the ECU is down beside the battery and the connectors to the ECU is a favourite place for the water to get in which can lead to corrosion of the pins and bad contacts. It could also be a connection to the TPS or one of the sensors. The ECU should store fault codes for any sensor which gets out of range or doesn't make a connection and the dealer should be able to access these.
It's a good idea when you have the fairings off to go over every electrical connector on the bike making sure they are clean and free from corrosion and to fill each of them with dielectric or silicon grease to keep the water out in future.

Gizmo
25.05.2006, 10:04 AM
Does it have the race ecu as well as the race can?? I didn't fit the race ecu , its set up for more hig revs trackwork so low and mid range aren't as good.

Sounds more like water though, dry, silicone and check both coils including the vertical cylinder, water can sit in the plug indent. Make sure its not something stupid like the left hand petrol pipe not sat in its groove under the tank and thus putting pressure on the coil lead

Freak
25.05.2006, 10:12 AM
Does it have the race ecu as well as the race can?? I didn't fit the race ecu , its set up for more hig revs trackwork so low and mid range aren't as good.

Sounds more like water though, dry, silicone and check both coils including the vertical cylinder, water can sit in the plug indent. Make sure its not something stupid like the left hand petrol pipe not sat in its groove under the tank and thus putting pressure on the coil lead

Good point, this was indeed the issue with mine the vertical coild failed because the fuel line was not seated in the channel under the tank correctly and vibrated on the coil causing the failure (although I did have the old type of coil also)

john
25.05.2006, 11:21 AM
Was going to take it for a ride and found battery is dead flat, IE 0 volts. This happened once before and I was sent new battery which I didn't fit as the current one charged up fine and has done 300 miles plus since. Ironically I sent the new battery back to Ducati Glasgow two days ago! I assumed it was my fault the battery had died, ie left it on park for a week. Maybe not.

It has the correct ECU. This is definitely a change in running rather than a characteristic caused by poor mapping etc.

The original dealer set it up, and checked this problem out last time it happened. Maybe my new dealer will have better luck/skill.

While waiting for the Optimate to recover or condemn the battery I will go and carry out some of your suggestions. BTW did pull out front coil but it seemed very well sealed. I suspect a coil going would be more obvious, I use copious quantities of Duck Oil and rubber grease on the bike. I suspect it is too new to have corroded contacts but you never know.

Thanks for all your very rapid and very helpful suggestions.

alane
25.05.2006, 12:53 PM
Don't know how easy this would be but, can you get them to check the contents of the "scavenge sump" in the bottom of the tank for grit/sand. Probably need a long thin tube or summat.

john
25.05.2006, 03:27 PM
I think it is probably the battery and nothing too subtle. More I thought about it I realised that the stutter went after the battery had its last cardiac and was then defibrillated back to life. So probably an intermittantly dodgy cell. Quite pleasing really it being one of the few Jap items present! Shouldn't really say that these days seeing as how I make my money selling some very reliable Nipponese phono cartridges! (and yes they'd far rather be called Nipponese than Japanese)

Anyway tanks been off, no obvious chafed wires and both coils are dry as a bone. There is nothing to hold the fuel pipe in its 'channel' so they could quite easily touch the coil.

Anyway the coils are out of circuit when the ignition is off I assume so even if one had gone short it would only affect the battery when the bike is running. And no I don't have an alarm etc, all bog standard.

Battaery is slowly coming back to life, will let you know what happens tomorrow or later tonight...

Slainte

john
25.05.2006, 03:30 PM
Does it have the race ecu as well as the race can?? I didn't fit the race ecu , its set up for more hig revs trackwork so low and mid range aren't as good.

Sounds more like water though, dry, silicone and check both coils including the vertical cylinder, water can sit in the plug indent. Make sure its not something stupid like the left hand petrol pipe not sat in its groove under the tank and thus putting pressure on the coil lead


I asked the dealer about using the standard chip with the open exhaust. Think I might follow your example here. I take it that is the ECU to the left of the battery?

Freak
25.05.2006, 03:43 PM
There's no clips etc for the "channel" under the tank but you'll see 2 indents for use of a better word where the fuel lines should sit, they tend to pop out sideways when you lift the tank and refit it

john
25.05.2006, 03:46 PM
Cheers Freak, have made sure they are sitting in their grooves

john
26.05.2006, 08:49 AM
Have charged battery overnight. Optimate went straight to yellow charge and stayed there all night - 19 hours. Optimate say this can indicate problems. But it eventually got back to 14 volts. Reset Optimate and within 1 hour got green light, just like the last time we went through this. So put it back in bike. Worked fine but who knows when it will discharge again. Not road tested yet to see if stutter is gone as it is pouring down here now.

Will do later today though, meanwhile shall get new battery.