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Discussion Starter #1
Here's the situation -

My bike has recently gotten a 12K service, and one new exhaust valve (old one was burnt). The shop noticed some low speed hesitation and roughness and after much diagnostic work thought they had traced it to a vacuum leak. So I pick up the bike and notice that it once it is warm it runs very rough at the 2500 rpm level or so, either on acceleration or trying to go through a corner. I called them and they said to bring it back in because they thought the fix might not have cured it permanently.

So I'm wondering, what could be the source of the vacuum leak? Are there other things that could be contributing? (I have removed the emissions system and plugged the throttle bodies with stainless M5x10 bolts (the 10mm length seemed long, but I couldn't find anything shorter in stainless)).

So I'm hoping one of the monstergurus out there can shed some light on what might be going on.

Many thanks!
Michael
 

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I suspect the TPS setup first whenever a Ducati EFI bike runs like crap at low speed low throttle settings.

Look at the screws holding the TPS on the bike... they've got yellow sealant over them. Then ask shop to adjust the TPS. You'll get the bike back and the yellow sealant may still be there.

A friend had same problem and they said they adjusted it but the protective paint was still on TPS from factory. It was set to 1/2 the required value. ::) After we redid it, his bike ran like a top. Granted his is 916, but the EFI is remarkably the same.

:) Chris
 
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I am with Chris on this one....especially since you have a 2000 M900.
The shop was finding alot of them off once they found mine was.
May not be but I would have them check it too.
 

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Discussion Starter #4
Thanks guys, I'll have 'em check it out. Just so I know, where is the TPS located? (Yeah, I'm a tech-moron).

BTW, this is the reason I love working on this board!
 
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follow your duct under the airbox on the left side; near the coil you will see it and it will resemble this...you will prolly have allen screws and it will say marelli
 

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Discussion Starter #6
To close the loop on this thread I thought I'd post the culprit - a defective spark plug! Turns out a new plug installed had an electrode that was off center by a couple of mm or so. I looked at it and if it wasn't pointed out to me I would have missed it. I guess it was not firing some of the time, but enough to keep the bike from being on one cylinder entirely.

Anyway, popped a new one in and it runs like a top. Go figure...
 
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Good to hear you found the culprit......I guess I will stop assuming a shop would have found that right away.
 
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