Need some help with a fueling problem - engine is stuttering.

[colacin]

Advice required as my local shop is 'stumped'.

I took my 4500km S to a local dyno to get a baseline reading. I have the full termi 2-1 (baffle removed), a DNA filter, and an STM Evo 45deg slipper clutch - no other engine/drivetrain mods.

The dyno run came back exactly as what I've found online for a stock HM - 80hp and 66 ft-lbs. There was no attempt to change any setting on the bike, and he did about 6-7 runs all told.

After the run, I went and filled up the tank around the corner and on the way home noticed the engine was hesitating and stuttering from 4k on up, and was really prevalent between 4-5k. I would open the throttle and sometime it would rev and sometimes nothing, then rev, then nothing, etc. It was also backfiring very frequently. It had done nothing like this before. There was no noticeable smell of gas that might indicate a leak somewhere.

The bike's been to the dealer who has inspected everything and found nothing outwardly wrong, as in loose or disconnected, the tank was drained and fuel replaced, hooked it up for diagnostics which reports nothing wrong, and tells me the bike is running very lean. He doesn't know why.

So far, the fuel pump and filter have been replaced and this hasn't changed the condition. I get the feeling that if I don't tell him what I want checked / replaced he isn't going to do it or doesn't know what to do, or at least doesn't want to carry out work without knowing if Ducati is going to reimburse him.

Anyone have any similar issues, or at least have some ideas? I would expect a bad fuel injector to show up on a diagnostic scan, but maybe not.

[colacin]

C'mon guys! For once the forum is strangely quiet... Do I need to pull some kind of 'subframe thread' quote out of my @$$ to get some buzz going?

Anyhow- right now mechanic is pointing the finger at the DNA air filter. Unless the thing has catastrophically failed I can't see how that is causing my problem. Especially since the last 1500km with it installed have been trouble-free.

[freezer16801]

DNA filter? Sounds like he is trying to make it someone else's problem besides his own. You could always call Ducati North America and tell them your problem. Maybe they could assist the dealer with some ideas on what else to look at for the problem source. I know when I called about my shifter being stuck, they appointed a regional service manager to oversee the problem.

I would've suggested spark problem, but you said it is very lean. I have heard of some ECU's going bad. Maybe search up the faulty ECU thread?

[george_v]

Originally Posted by colacin

Anyhow- right now mechanic is pointing the finger at the DNA air filter. Unless the thing has catastrophically failed I can't see how that is causing my problem. Especially since the last 1500km with it installed have been trouble-free.

sorry to hear this mate! I use DNA air filter and no problems whatsoever! So for sure this has nothing to do with your problem.

did he check the injection? as all this seems to me as an injection problem. Also i remember some guys in here reporting similar issues in the past.

[colacin]

Update-

They took out the DNA air filter and replaced it w/an OEM one and 'now everything's fine, so it must have been the DNA filter.'

The problem certainly is gone- but I don't believe it was the air filter, so obviously I will have to put it back in... I think there was something else wrong *somewhere* that did the trick when he put everything back together.

On another note, I did get some new Pilot Power 2CTs put on, so we will see how they work. They feel a bit more squirmy out of the box...

[tunefx]

Ahhh, a subframe challenge! More on that later.

This is a long shot. Had a similar problem on a old dirt bike of mine with a cheap filter and lots-o-mods to the airbox. It took me a while but I discovered the air filter unit was collapsing at high RPMs. The result was a major engine stall at speed due to choking the air intake. I'm not suggesting you have the same problem, only that I've seen a similar problem with the air intake.

Other than that I recall back in th early 80s I had an old Suzuki with a bad coil that would break down at high-rpm. But the "stall" was extremely severe.

Wish I knew more! Everyone on this site is far more knowledgable about Ducs than me. I'm trying to catch up!

Ok, back to that comment you made...

Originally Posted by colacin

C'mon guys! For once the forum is strangely quiet... Do I need to pull some kind of 'subframe thread' quote out of my @$$ to get some buzz going?

With a name like "colacin" it sounds like you have the perfect perscription drug for post quote pulling colon treatment. Sorry, I just couldn't resist! Nothing personal. Seriously, I think you should protect that name and sell it to one of the big pharmas! It's a great product name. And, after this response, I'm sure some folks will advise me to buy a case and take it twice a day!

[colacin]

So that's more like what I expected- a novel possibility + a bit of a jab to go along with it. Nice one, tune.

I hadn't really thought about the name before, but when I think about it, it does kinda sound like that "Talk to your doctor to see if Colacin's right for you..." I'll leave the side effect jokes for someone else.

[tunefx]

Originally Posted by colacin

"Talk to your doctor to see if Colacin's right for you..."

Thx! My wife is wondering why I just spewed my drink all over the carpet. I read this right as I was grabbing a drink and totally lost it! I know, TMI. Very creative!

You have to copywrite this name!

[BillyD]

Even though you have the Termi 2-1 installed, you made no mention whether the:

1) 2-1 ECU was installed (one must assume that it was);
2) TPS was reset
3) Fuel Trim adjusted to ~5% CO at idle.

If all of the foregoing was done, you should be in the upper 80's HP-wise with very smooth off- to on-throttle transition (i.e., no snatchy throttle).

Bear in mind this is MotoGP weekend at Laguna Seca, so most Californicators are out doing, not posting.