Rough at flat / constant throttle

[KPhinney]

Hey Crew,

If this has been covered elsewhere and I've missed it in my searches, feel free to point me to old threads.  

I bought a 2008 SR4S last year (998 Testastretta, 9,200 miles).  Since it came, I've been struggling to track down a cure to my rough running at flat throttle.  Holding it steady at an RPM of 3500-5400 feels like I'm running over ruts and twigs.  

Last year I swapped out the Champion plugs for NGK Iridiums and didn't notice a difference, but this weekend I moved back to new stock Champions and it got a lot worse.   Perhaps I didn't notice the betterment.  I adjusted the chain tension maybe 6 months ago and checked it this weekend.  

She starts fine and is smooth at idle.  Acceleration is mostly smooth.  The previous owner had the 7,500 mile service done on time and I purchased it with 8,200.  Termi exhaust and ECU.  The airbox had the top chopped off.  I strictly run ethanol-free 89 (US), but the previous owner did not judging by the tank swell.  

Any guidance is appreciated.

[greenohawk69]

Is it gas at the same vendor? Maybe bad gas. Try a different vendor.

[Howie]

This should probably be added to your old thread since there is a history if it is the same bike.  Anyway,  it would be a good idea to start with is basic adjustment: valve clearance, valve timing, TPS setting and throttle synch. 

I'm not sure about this, but, if closed loop can't compensate, your open lid may be the problem if you are running the computer at factory settings.  Partially close off the air box and see if it gets better.

[KPhinney]

New info.   I looked at this post on MPG and was astounded.   

http://www.ducatimonsterforum.org/index.php?topic=1913.0

I've been tracking my milage and gas consumption for the last dozen fill-ups.  I'm getting an average of 27 mpg, which looks to be about 1/2 what I should.

How might this factor in?

[S21FOLGORE]

How well do you know the history of this particular bike?

How well do you know the previous owner ?

The previous owner had the 7,500 mile service done on time

Do you have the paper work?

Termi exhaust and ECU.

Slip on, or full system?

The airbox had the top chopped off

Do you mean by that the stock air box rid is cut off ? Or are those three items (Termi pipes, ECU, open top air box rid) the ones sold as Ducati Performance kit?

Do you like the bike? Do you think you are going to keep it for long time?

Perhaps, at this point, it is best to bring the bike to someone who can run it on the dyno and reflash / reprogram ECU.
You can spend months for searching on the net, trying to solve the problem by yourself.
Or, one or two trips to dyno run, and all the problem solved.

[S21FOLGORE]

FYI,

Symptoms of maladjusted TPS

The bike will run like crap ALL THE TIME. NOT like running sweet in condition A, but sputters/boggs/backfires in condition B.
Typically happens when DP kit (new exhaust and ecu) is installed by the owner at home.



Things you can try by yourself

for mid range, ride at a steady throttle in your normal rpm range and crack open the throttle.

If there is a slight bog or hesitation, then good acceleration, you are a little lean in the mid range.

If there is a bog and burble and not good acceleration till you back off the throttle a little bit, you are rich.
You'll also have soot in your tail pipe.

idle, from the factory its always a bit too lean.
Most stock engines are,
tuned to be lean at idle to pass emissions and
rich at top end to prevent overheating and burning a piston.

Also, there is a very good reason to run top end mid range a little lean, it makes WAY more power than too rich.

There is no simplistic answer for running lean/rich. Any engine can be lean at idle, rich at midrange and just right at top end all at the same time.

Reading spark plugs
You can not look at a spark plug that has been run for an length of time and tell anything specific from it, unless the engine is drastically lean or rich. In that case, you already know before looking at the spark plugs.

The brown/ tan color thing was useful when gas was leaded, not anymore. Now plugs look slightly grey to almost clean.

If you are running too lean, you'll see small spots/dots on the plug insulator.
This is the first indication of overheating. Don't ride it like this.



There are just too many small thing that can be the reason of the problem you are having.

O2 sensor

rubber plugs on the throttle body

Barometric Pressure/Air temp sensor

etc, etc,

that's why I suggested going to someone with diagnostic tool and dyno.

[booger]

I had the same issue with my S4RT, I have a full Arrow system with a reprogrammed ECU to DP spec and chopped airbox lid. Took it to a dealer (DucPond) and had it bench tuned. Runs a little more consistent and civilized. However I think I'll take it in for a full remap/dyno tune this summer at some point to iron it out fully. It's a fueling issue most likely.

[KPhinney]

Is it gas at the same vendor? Maybe bad gas. Try a different vendor.

A couple different stations.  I have a few to chose from that cary non-E and I don't favor one.  

Do you like the bike? Do you think you are going to keep it for long time?

I'll start with that question:  Yes, very much.  It's the '08 Tricolore and I wanted one since I first saw it in 2008.

I felt the owner was on the up and up for the most part.  There were a few things he neglected to mention before I took delivery, but he gave me all of the service records.  I see where the Ducati dealer performed the 7500 service.  

This does appear to be the Ducati Performance Kit in all regards.   The kit was dealer installed - I have the papers on that as well.

Symptoms of maladjusted TPS
The bike will run like crap ALL THE TIME. NOT like running sweet in condition A, but sputters/boggs/backfires in condition B.
Typically happens when DP kit (new exhaust and ecu) is installed by the owner at home.

I think we can rule the TPS out based on what you've said.  However, I have TuneECU software and hardware and have done a bit of work with it on my EFI Triumph.  I placed an order for the Fiat 3-pin to mate it with the Ducati, which should arrive this week.  I have conflicting info as to whether TuneECU will work or if I need to learn the GuzziDiag software, but I hear that's not difficult.  I will reset the TPS.  Is there anything I should look to do before I reset?  What about afterwards?

[michael holmes]

I had a bad running engine because the fuel filter needed replacement.
The interval is 6000miles so maybe thats something to take notice of.
MH

[KPhinney]

Hi MH,

I hoped that to be the case.  I ordered two filters last week and will put one in this weekend, however, after seeing that other riders are getting 40-50mpg while I'm getting 20-30 I've little hope of it fixing my issue. 

[Speeddog]

IMO, S4Rs/t will only get 40-50 mpg downhill with a tailwind.
Same for S4R Desmoquattro.

More like ~35 for those bikes on any sort of realistic riding.

I can get ~43 on my S4 with mixed riding.
An old riding buddy had an S4R, he was smaller and lighter than me, first long ride with him he ran out, and I had more than enough left to go get a jug of gas to get him to the next station.

I've got a Microtec ECU on it, and in fiddling with maps I've put in one that's richer, and the bike runs better and gets better mileage.
Sometimes it's not as simple as it seems.

Try the fuel filter, and check the intake 'sock' filter to make sure it's not mucked up.

[Moronic]

I would keep in mind as a possibiiity a worn or otherwise corrupted throttle position sensor.

Sounds unlikely given the low mileage but these bikes are 10 years old now.

I had a similar sounding - although not identical - problem with my S4Rs, and after changing just about everything on the bike to no avail, a fresh TPS did the trick.

The old TPS came up fine on diagnostics. But obviously it was worn or otherwise corrupted and sending a poor signal.

Problems arose at about 35,000 miles after the bike had an Arrow exhaust fitted and a tune. (I started a thread, which I should get around to updating. Tracing the fault took forever, for a range of reasons. I mean years.)

The common bits are the poor running at steady throttle in roughly the RPM range you quote, and the poor fuel consumption.

Old TPS got roughly 35mpg (US), sometimes worse. New TPS consistently 45mpg, and rarely drops below 42 even on entertaining roads. (Note that the bike has been dyno tuned, and so is not running the notoriously rich DP map.)

The TPS is in theory a non-replaceable part of the throttle bodies. In practice, the part is available cheaply from CA Cycleworks and Gotham.

Note that replacement is not a simple job. And the first time I had it replaced, it didn't help (part of the reason for the long diagnosis period). The successful time, I had a low-mile used set of throttle bodies fitted - but the TPS was the only significant change.

With a faulty TPS, mine idled okay and was pretty good under acceleration and up top. Good enough that successive experienced mechanics could not pick an issue. But on steady throttle at open-road cruise speeds she felt unhappy and rough - a subtle difference but very noticeable for an owner familiar with the bike and how it could run.

As I say, just a thought if nothing else seems to help much.

[KPhinney]

...
The common bits are the poor running at steady throttle in roughly the RPM range you quote, and the poor fuel consumption.

Old TPS got roughly 35mpg (US), sometimes worse. New TPS consistently 45mpg, and rarely drops below 42 even on entertaining roads. (Note that the bike has been dyno tuned, and so is not running the notoriously rich DP map.)

...

With a faulty TPS, mine idled okay and was pretty good under acceleration and up top. Good enough that successive experienced mechanics could not pick an issue. But on steady throttle at open-road cruise speeds she felt unhappy and rough - a subtle difference but very noticeable for an owner familiar with the bike and how it could run.

Moronic - that sounds frightfully like my issues.  Would an out of sync TPS share the same issues?  I finally have all of the pieces ready for a reset this weekend. 

The weekend plan:
1) Close off portions of the open air box.  Ride.  Repeat. 
2) Software TPS reset if I can get  (in this order) MelcoDiag, JDiag, or GuzziDiag installed and running. 
3) Short of that, I have the instructions and voltmeter to dial the TPS in manually.  ***
4) Replace the fuel filter.  I'd do this first, but the tank is close to full.  I'll draw it down by observing the output of the above.

*** I find it odd that the #2 and #3 yield the same results.  Have I misread this in other posts?

[Howie]

You cannot set that TPS manually, it is not adjustable.  If you can't cat your software running a shop shouldn't charge a lot to set it.

[Moronic]

Moronic - that sounds frightfully like my issues.  Would an out of sync TPS share the same issues?  I finally have all of the pieces ready for a reset this weekend.  

I can't comment from experience on the out of sync TPS. But since the reset is such a quick and simple job for someone with the right diagnostics, it is an obvious prior step.

As Howie says, if you can't reset that yourself, get a shop to do it. I've seen it done and it doesn't take long.

If you do end up looking to replace the TPS, I would recommend you seek out a tech who has done this before with success. The original TPS is a one-way snap-fit, and I think it may also be bonded to the throttle body with a sealant of some kind.

Apparently it is quite difficult to get the original out without destroying it. Then the new one has to be fitted properly and re-synched.

Add to that the possibility that the new one will be faulty. CA Cycleworks, which tracked down and wholesales the individual part for us all, has posted on how they now test every TPS they import for accuracy using a proprietary test unit - and reject plenty. The TPS will come with a certification that it has been tested. But the test process may not be infallible, and it may not be out of the question that the unit could be damaged in the fitting process.

I saw an interesting post once on what was inside these (example used being a Yamaha FJR IIRC). It is a mechanical part, with the bits that modulate the signal requiring precision manufacturing and prone to wear and materials breakdown. The wear is most likely in the places where the TPS is most used - hence the likelihood of better running up top. Plus, on these bikes the ECU interpolates the signal: the reset gives it the top and bottom limits, and it makes inferences about the data it gets in the middle (as I understand it).

Anyway, if it comes to this you may find help here from people experienced with TPS replacement on the Testastretta. Due to the complications, I would not rush in there. But if everything else checks out and you are scratching your head, it's another path to go down.