[PhilCurrie]

I have seen a lot of posts where Ducati's seem to have an issue where the bike misfires around 4K when warm.

Have replaced fuel pump, relay, air temp sensor, wiring to pump.

All things I have seen others replace along with the ecu, coils and water temp sensor.

Has anyone actually fixed this issue. Even my bike shop has not been able to fix it with a month of trying.

 

[Tuned]

It does it on deceleration right?

 

[PhilCurrie]

Not on deceleration. It is when I give it gas from 4K it acts as though it is not getting enough fuel. It coughs and loses power to the point I usually have to pull over and let it cool off.

 

[Tuned]

Hmm… Ok I guess it's time to figure out what bike it is!

 

[PhilCurrie]

It is a 2005 ST3 with 64K miles

Going back to the shop this morning for the 3rd time.

 

[Shazaam!]

Dirty air filter and/or fuel filter.

 

[Tuned]

Dirty air filter and/or fuel filter.

I assumed since it's been at the dealer many times and they replaced the pump, that it's probably not an obvious issue like a filter. But hey, dealerships can be really that bad sometimes!

If it works fine when it's cold then I don't personally feel the filters could be a problem.

My initial idea was electrical. I'd love to see what the battery voltage is like when the bike is hot.

 

[Proctologist]

Sounds like its fuel or spark related..

Did they check spark plugs/gap and ignition coils ?

 

[Shazaam!]

If it works fine when it's cold then I don't personally feel the filters could be a problem.

A lean condition is a common cause of misfires. When the engine is first started up cold, the ECU is programmed to supply excess fuel at all engine rpms to aid in cold running. Once the engine is up to temperature, the fuel supplied by the ECU via the injectors is reduced across the board. If there is an dirty fuel filter, the bike will run lean.

 

[Tuned]

A lean condition is a common cause of misfires. When the engine is first started up cold, the ECU is programmed to supply excess fuel at all engine rpms to aid in cold running. Once the engine is up to temperature, the fuel supplied by the ECU via the injectors is reduced across the board. If there is an dirty fuel filter, the bike will run lean.

Got ya… didn't think about the cold running mode.

 

[219R]

Shazzam !!

 

[Proctologist]

Got ya… didn't think about the cold running mode.

Neither did I .. Shazaam makes an excellent point about the extra fuel when cold.

Lets see what the OP reports back -

 

[PhilCurrie]

Dropped off the bike today, they are going to replace the ignition timing sensor. I will keep you updated and let all know if it helps.

 

[oleary]

Stick coil.

 

[Tuned]

Dropped off the bike today, they are going to replace the ignition timing sensor. I will keep you updated and let all know if it helps.

It's why I said electrical… not to discount Shazaam's excellent reasoning, but having experienced this problem before with the airbox cover off (no filters) I do feel its something else then simply not enough air or fuel.

I do look forward to hearing what they found. We have another member with similar issues on his 848 and it makes me wonder if there is a straight forward solution.

 

[PhilCurrie]

Just talked to the folks at the shop and they believe they have solved the problem. Simplicity itself the side stand switch. We are having unseasonably warm weather and when they tested it, the switch finally failed to the point that it would die as soon as it was popped into gear (kind of obvious what it is at that point) They by passed the switch and the problem is gone. Getting it back next week, and I will let you know the results. I am pretty confident this is going to fix the problem in light of this. For the guy with the 848 he might want to bypass that switch and see if that fixes the problem for him as well.

 

[Tuned]

Ahh, so the switch was loose and cutting the ignition during certain vibrations?

Hmm… yea maybe. Good diagnosing from your shop.

 

[Tom1198]

I had a similar problem and it took a while to figure out it was the TPS. It was around 4000rpm but only when I had the throttle cracked open. It was at a position to lee the bike moving at the same pace. I did have the dealer look at it and they tested a ton of stuff and couldn't figure it out. Once I realized what it could be the part was inexpensive and after the 5 minute install I just had to reset the throttle position sensor with a program a friend had.
It was so bad it would chop when I hit a certain spot on the throttle. Violent at times too

 

[Tom1198]

Here is a link to our conversation about it last year
http://www.ducati.org/forums/showthread.php?t=59016

 

[Tom1198]

Btw the dealer told me it was the kickstand switch and it wasn't.