Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 999 / 749 > Cutting out

[Micey]

Hi

Just picked up a new 749s 04 spec and it keeps cutting out when its idling. It's especially annoying when I'm stopped at the lights!! I don't want to take the bike back yet, cause its too much fun and the first service is only about 2 weeks away. Anyone else get this problem and if so, how did you solve it? Cheers.

[sbwells]

Mate, I've got the same bike and its not a problem provided your dealer can set it up properly. There isn't a problem with the bike, just some dealers are better at solving the problem than others.

You can use the fast idle level to keep the bike ticking over around 1300rpm till you get the bike serviced and set up properly.

Here is the fix:

remove access plugs on the LH side of the airbox (there are two)

Loosen the screws holding the airbox lid on so you can pry open the back of the airbox about 1/2"

Once the airbox is pried open you will be able to see the throttle linkage on the rear throttle body.

There is a 4mm allen set screw for idle speed that points upward toward the LH lower corner on the top of the airbox. Drill a hole so you can adjust this.

Set the air bypass screws all the way in.

Connect vacume balancing guage to the ports on the intakes.

Start motor (it won't want to idle)

Balance TB's with the balance linkage inside the big access port in the airbox.

Set the bypass screws at 3/4 of a turn out.

The bike should be idling at about 1200rpm's

Shut the motor off

Connect the Mathesis to read TPS setting

Back off the idle setting untill there is a gap between the set screw and the tab that it effects (zero idle preload)

What does the TPS read? If it reads zero you will need to wind in the set screw till it treads 2.8+ deg and then re-set the TPS. Now wind the idle back out again.

So now you have a TPS reading of .5+ or so (as long as it's above zero). And the set screw is not touching the linkage.

Take whatever the TPS reading is and add 2.3deg. So if it read .5 and you add 2.3 you come up with 2.8. Wind the set screw in till it reads 2.8deg. Then re-set the TPS. It will ow be assigned a value of 2.3 and you actualy have 2.3 deg on the trottle blades.

Set the trimmer at +20 (this is a starting point for CO's)

Start bike

Play with the air screws till the idle is 1200RPM (the screws should never be more than 1 1/4 turns out).

Recheck balance, TPS setting, CO's

I think this covers it, does it make sense?

[Micey]

Cheers mate. Thats a bit over my head I think, so i'll just leave it to the dealer to sort out when I take it in for the first service.

I had a Harley Sportster before this bike and I took a 749 out for a test in Bristol Ducati just to see what it felt like really. I traded in my Harley the minute I got back from the test ride. I love Harleys and the look of them, but there's something special about the look of the Duc I think (especially the "S" with the gold forks) and the riding pleasure is second to none.

[KeefyB]

Originally posted by sbwells
Mate, I've got the same bike and its not a problem provided your dealer can set it up properly. There isn't a problem with the bike, just some dealers are better at solving the problem than others.

I agree,my 999 used to cut out often when I stopped at traffic lights/junctions/etc.Annoying,but would always fire up again first touch of the button.The bike was booked in at Italia Moto,Lincoln for a service.The injection was checked and re-set as part of the service and its never cut out since.

[typer77]

I always hear other members mentioning TPS setting. What does "TPS Setting" refer to? Thanks.

[Jools]

Throttle Position Sensor.

It's a potentiometer (like a volume control on a stereo). When you wind the throttle open all you're doing is turning the butterfly valves to fully open in the throttle bodies. You're also turning the TPS.

Depending on where the TPS is set at it produces a different voltage. From that signal the ECU can work out how far you've got the throttle wound on, therefore how much the butterflies are open, therfore how much airflow is going into the engine and therefore how long a pulse it needs to send to the injectors and keep them squirting enough fuel in for the air/fuel ratio to be right.

The ECU takes a whole bunch of other stuff like the engine temperature, the crank position and the RPM the engines is at into account as well before it decides how much fuel to spit in, but that's about the size of it.

[typer77]

Thanks for the clarification!

[Wylie1]

Originally posted by Micey
Hi

Just picked up a new 749s 04 spec and it keeps cutting out when its idling. It's especially annoying when I'm stopped at the lights!! I don't want to take the bike back yet, cause its too much fun and the first service is only about 2 weeks away. Anyone else get this problem and if so, how did you solve it? Cheers.

I totally agree with keefyb....It's all down to set up. What area are you from Micey? If you let us know, I'm sure you'll receive a few recommendations for good places to get your bike serviced properly.

Cheers,
Lee

PS. Good choice of bike.

[mab]

Yep mine cut out too at idle, but problem solved at first service! (which i wasnt charged for)

[Micey]

I'm from South Wales, but I'll probably take it to Ducati Bristol on the first service and let them sort it out. Cheers for all the replies, when I spoke to the dealer the other day about the problem, he said he'd never heard about the problem before, so now when I take it back I can tell him how to fix it!!