998 stalling

[robb916998]

2004 998 ,started late last summer ,out for a ride ,every thing seams to be in order ,had a absolute blast going out and around my favorite roads around town .come up to a stop sign and ,,,,dead !
Start it and proceed , next stop may be fine but may die .
Now after servicing last spring , shimmed ,belts,plugs,wires ,extra love WITH pixie dust sprinkled on it ,

ITS worse .

its guaranteed to stall at a stop now , feels like riding a old British bike not a super bike.
WTF am i over looking ??

[Mark Phillips]

My ST4s stalled at stopsigns right from the factory. First service... no improvement. Second service (different shop)... much worse. I began to think it was normal. Third service (different shop again)... the guy spent a lot of effort balancing the throttle bodies and setting the TPS... the bike never stalled again.

[cm250to999]

On your own, you can try opening the air screws on each throttle body. If there is a rich enough mix available, that will raise the idle. If everything else is good, the screws should be open about an 1/8th-1/4 turn out from where the engine starts to stumble. If you get backfire the mix is too lean - screws need to be turned in &/or mix richened.

Proper setting of non linear TPS is critical. Linear type have no slots for mounting screws, and are set through the ECU. = very stable. Early slotted type are set with scan tool direct to TPS. Idle stop(s) have to be backed all the way off, and a bit of a touch to find lightly full closed position. There is a way to set these with voltmeter and 9V battery, never tried it....

On a very few bikes, I've had to raise the throttle stop screw. Which, your not supposed to do. If nothing else works,....

[Mark Lussier]

Sounds like my 350. It, of course is a Duc.

All my Brit bikes run just fine at idle and don't stall. My Commnado once idled itself from the centre of the road all the way to a culvert where it promptly fell over and continued to idle.

Please don't compare your 998's idle problems to my oil pissings Brit bikes. It's just not fair.

[robb916998]

Thanx for the info mark phillips,cm250to999(Chris).
That was the way i was leaning ,balance and flow . I cleaned the throtel bodys in spring but it had no positive efect.
I will look into balancing and min air flow this winter ,also set of the tps.
Only Brit bike I had ever had time on was a 67 velocett ,it would NOT idel and I was told by the owner it was my resposibility to idel it with my wrist! Well I failed ,It died and them wonderful wet velo clutches just don't work or work to well (not shur on that)when hot.
I just told the owner it was his resposability to go get his bike that wont idel or start now 5 blocks away !!
It's allways fair to compair PISSED OFF !

I duno Mark ,sounds like you have British personal problems.

[robb916998]

Can any one else hear crickets ?

Come on mark I was expecting some form of back lash to that post !!

[4theloveofducati]

[Mark Lussier]

Someone you know has a very handy manometer and a bunch of fittings that fit just about anything. It's been known to work on Brit bikes and works wonders on inline Japanese 4's.

[cm250to999]

Some interesting info here;
http://www.bikeboy.org/ducati2vthrottleb.html
I'm sure there is more out there. Back probe of harness is usually best done by taking plugs from an old harness to make a test patch-cord. That way you don't injure the harness.

Here's an example; Almost all the fuel injected bike use the same plugs for the fuel pump. I have a patch-cord for that, which allows me to put an ammeter in series with pump power. Less than 4 amp draw = hose blown off, no pressure build. Over 6 amp = plugged filter, pump seizure.

Same concept should allow TPS voltage reading. You can read in the article the big bear. Each throttle body has an idle stop that has to be backed off. PIA

"First 30 degrees of movement of non linear TPS the most sensitive" That's why if it is out of spec., all other tuning effort is pointless.

I've had a newer bikes with linear TPS, but Termi system thrown on. Since Termi burn ECU has what the heck ever defaults, if reset not done = bozo readings. Long to short, had a bike tell me it was at part throttle when it was actually closed. So if ECU has bad info....