[SFduc749D]

I've got an '06 749D that stalls at stoplights until the engine reaches normal operating temperature. This seems like a common issue for a lot of people with this bike and most have seen results after resetting the TPS with the Technoresearch VDST. I'm interested in purchasing the VDST, but wondering where to find the factory settings to know what values should be displayed on the screen with the VDST connected? Is resetting the TPS a simple click of a button or do you have to enter a specific value in the program. My bike is currently has all stock engine/exhaust components and I just replaced the spark plugs (NGK CR9EIX) and ran fuel injector cleaner through it with no results.

 

[JohnMH]

The rheostat in the throttle bodies produces a voltage signal between about, say, 90 milivolts at closed throttle (ie the TB plates only open on the idle stop) and about 1 volt at wide open throttle.

You can in theory open the airbox lid, plug a voltmeter into 2 of the 3 prongs on the TPS (power, ground and signal) and read across the ground and signal wire to check voltage as you roll the throttle open.

My 999R had a bad TPS from new, putting out a signal of about 400 milivolts. The bike was gagging rich at low rpm and very lean at high rpm. But still ran (barely).

A nemesis ECU fixes all of that, but is pricey. Borrowing a DDS machine from a dealer for an hour is an easier way to check and reset your TPS, but you need to know how to use the DDS.

If you have not changed anything and your TPS works, it would seem odd for the TPS signal to get out of synch with the ECU.

There is an enrichening timer in the ECU which keeps the mixture rich for a preset amount of time unless the water temp sensor says it is warm.

Maybe check the water temp sensor while you are in there or swap it out with one from another bike which works to test it?

I wonder if a stuck open thermostat would send warm water to the temp sensor earlier than usual and cause the ECU to lean out the mixture before the engine is fully warm? Hmmm...

 

[DuckMan]

In the later model years, like yours, the TPS is a fixed linear device. The only setting is in the ECU which is set to a factory specified number of degrees. Usually somewhere around 2 degrees. In VDSTS it is a single click and does just that. There are no options on this and it will only set it to the factory specified value. On these bikes it really doesn't ever change and you probably won't gain anything by resetting it. Most likely you will see an improvement by setting the fuel trim to a higher (richer) value which can also be done using the VDSTS. When you start up VDSTS just take note of the origional factory fuel trim value and write it down somewhere so if needed you can go back to it. Start off by increasing the the value by about 5 units. You should notice an improvement in low speed running and stalling.

 

[BrianG]

In the later model years, like yours, the TPS is a fixed linear device. The only setting is in the ECU which is set to a factory specified number of degrees. Usually somewhere around 2 degrees. In VDSTS it is a single click and does just that. There are no options on this and it will only set it to the factory specified value. On these bikes it really doesn't ever change and you probably won't gain anything by resetting it......................

On doing my first tune-up on my 2005 999S, I noted that this value required resetting after sync'ing the TB's.

............................................... Most likely you will see an improvement by setting the fuel trim to a higher (richer) value which can also be done using the VDSTS. When you start up VDSTS just take note of the origional factory fuel trim value and write it down somewhere so if needed you can go back to it. Start off by increasing the the value by about 5 units. You should notice an improvement in low speed running and stalling.

This is most efficiently and evenly accomplished with a CO reading instrument.

 

[james0133]

I found the stalling issue was the idle adjuster screw on the Throttle Body is set incorrectly from the factory.

Have a look at this link originally posted by Bradblack:
http://www.bikeboy.org/ducatitps.html

 

[SFduc749D]

Thank you

Thanks to everyone for posting detailed responses and offering solutions. I purchased this bike a few months ago and have already taken it into a Ducati mechanic in San Francisco about a month ago. He test rode it and agreed it was stalling often, so he adjusted the fuel trim (said it was too rich), cleaned the air filters, adjusted the idle to 1100rpm. After those adjustments, it continues to stall until the engine warms up (usually stops stalling after water temp is 170F) and he thinks it because the throttle tube is going past the stop mark…causing the engine to stall. However in order for him to make the necessary adjustments to the throttle cable, I should wait until my 18k service because at that time he will remove the gas tank and I won’t have to pay for the gas tank removal labor twice. I have 2000 more miles to go before I reach 18k.

So given everyone’s recommendations for how I could fix the stalling problem, it sounds like something that could have been diagnosed and fixed on my first visit. Maybe he’s right about the throttle tube, but that doesn’t explain why I don’t stall after the engine is warmed up. Right now I could buy the VDST and try to fix it myself, but it sounds like my problem might require more equipment or tools to properly diagnose the bike. I guess it wouldn’t hurt to start w/ the VDST and if that doesn’t fix it, then take it to the shop.

 

[bpeeples]

Stalling

I had the same problem with an 06 749s. Ducati imports them too lean. The dealer's mechanic spent a lot of time getting it richer as per instructions I found from the Seattle Duc shop. They treated it as a warranty issue. It was a perfect cure. There was actually a chart published by Duc that gave the correct 02 numbers in the local dealers shop.
Try google for 749 stalling.
Good luck

Ben.