Tuned S4Rs stutters below 3K, rough in steady cruising: not the coil, after all

[Moronic]

Hoping the experienced tuners on the board can give me some pointers with this one.

Finally had an Arrows full exhaust fitted to my S4Rs, and the ECU tuned for it by my preferred workshop, using Tuneboy (which AFAIK allows complete control). Haven't been happy. Also haven't ridden a DP-chipped S4Rs for comparison.

Bike pops a lot on overrun, is very rough on small throttle openings under 3K, and has lost that smooth Ducati lope on steady throttle in top - all cruising speeds from 60-100mph (and probably above but I don't tend to cruise over 100). Roughish, so right hand goes to sleep.

Runs better when accelerating, and smoother and stronger than stock when accelerating above 7K. But still seems to lag the throttle a bit. I find myself winding on more throttle than I remember having needed stock to get the jump I am looking for.

But ... and here is the interesting bit.

On a longish ride last weekend she came good over one nice stretch of curves, and late in the day came good again over the last 60 miles to home. By came good, I mean she worked better even than I had hoped from the tune. Can't say too much about the low-end stuff, but the steady cruising felt wonderfully loping in the 55-80mph range where I used it over those stretches, the throttling felt wonderfully precise and fluid, and the harshness and roughness had gone. Bliss!

Started her for my commute yesterday morning and the roughness and popping was back.

So ... initially I had thought the tune needed adjustment for steady throttle conditions. But the intermittent perfection has led me to wonder whether the tune was superb but some other issue has arisen coincidentally with the tune being completed.

For example, has a bad connection to some sensor or other key part arisen from the dyno work?

My first guess is that the air pressure sensor has malfunctioned for some reason, leading to general leanness (but that it came back intermittently for the good bits).

Some key background:

- dyno result from the tune was 128hp max at the wheel, with baffles in and stock airbox (Dynojet). Stock was 115 max.

- I am sure the shop will work with me on this, and I sent them a similar query yesterday. Very good guys and I've been with them for six years. But it is a busy time for them and so I am looking for any intelligence I can muster that might help, so that when I do take her in again we can get quickly to the heart of things.

- I have been back once for a tweak, but that was prior to the experience of the bike coming good. The result was a small adjustment, which did help a bit. I am suspecting now that they just didn't consider the possibility that their entire map was compromised by a malfunction. (I certainly didn't, in explaining the problem.) Yes, they did test-ride when I brought her back in. But opportunities to test efficiently and thoroughly from their location are very limited.

- Fuel consumption: over the 100 miles before the last time she came good, 6.4 litres per 100km. Over the 50 miles after she came good, 5.0 litres per 100km (which is about what she returned stock under most cruising conditions). Over the higher consumption period I was also riding faster, averaging say 75mph compared with 60 for the latter period. So that would account for some of the higher rate. But I am sure the lower consumption was also connected with the smoother running. The motor felt soo much better (which is why I refuelled to test usage).

While the higher consumption during the poorer running might suggest that the fuelling was too rich then, my intuition is that in fact the bike when running poorly is lean.

Suggestions sought from those with some insight.

Update: diagnosis reported on page 2, reply 23.

Fresh update: Stepper motor theory. See page 3, reply 35.

New update: Not the coil, after all. Not the ECU either. Problem remains. Next step: the TPS. See page 3, reply 41.

[Speeddog]

Leaner does not necessarily mean better fuel economy, and richer does not necessarily mean better running.

Do have them check for proper function of all sensors.
New fuel filter wouldn't be a bad thing to try.

How many miles on the bike and when were valves last done?

All of that is baseline upon which to build a good map.

Then, ask them to concentrate on tuning the under 25% throttle zone.

[Moronic]

Bike has 33,000 miles, valves were done at the 30,000 major service, along with a new fuel filter.

Thanks for the input, Speeddog. Helpful info on the relation (or not!) between leanness and fuel use.

Hadn't thought about a fuel supply issue, but I daresay that is a possible. Just because the filter is new doesn't mean it's not picked up some rubbish.

The standout thing for me is that the tune has come good now, intermittently, as I noted above. I'm reluctant to fool with the mapping, because when it was good, it was very, very good.

Sounds like there is no obvious intermittent issue that would generate the symptoms though. Damn!

[Speeddog]

Valves and fuel filter done recently, so baseline is theoretically good.

~~~SNIP~~~

Sounds like there is no obvious intermittent issue that would generate the symptoms though. Damn!

Quick check with diagnostic software will determine if sensors are giving believable readings.
Perhaps a sensor electrical plug isn't secure, or a terminal is pushing back when the plug is connected.

It would be worth disconnecting, visual check, and reconnecting electrical plugs, watching the wires to see if they push out.

Bike been exposed to water recently?

[Moronic]

Thanks again for the conversation, Speeddog. I picked up some conductive grease last night and plan to check some electrical connectors/plugs today, beginning with the air pressure sensor.

Bike is ridden in all weathers. Have had a previous non-start issue that turned out to be a corroded connector shorting the main fuse.

So, a problem with an electrical plug sounds quite likely.

What do you mean with "a terminal pushing back"? Broken plug with a pin failing (or partially failing) to enter its socket?

[Speeddog]

~~~SNIP~~

What do you mean with "a terminal pushing back"? Broken plug with a pin failing (or partially failing) to enter its socket?

Yes, either the plastic plug cracks/fails or the locking tab on the pin or socket fails.

It's not common, but it can provide no/intermittent contact in a plug connection that looks perfect.
Usually the pin/socket mate just enough to pull back into position when the plug is disconnected.
So a visual inspection of each  plug half shows all pins and sockets look good and in position.

[Moronic]

Got it. Thanks very much. Would never have looked for that. 

[Moronic]

Problem seems to have been sorted. Not definite what was wrong but a 20km test ride tells me she idles smoother, runs smoother, has much better throttle response and is smoother on overrun. Still a few stumbles around 2k and 2 per cent throttle but nothing like it was.

Bet she has more up top, too.

The air pressure sensor plug looked clean and dry but I added some dielectric grease before closing it up.

Also looked at the big plug behind the steering head that had blown the main fuse a few years ago. Noticed it had not been seated fully home in its socket by the last person to pull it. Added some grease and seated it properly.

Think I pulled and greased three other plugs that were easy to get to. One was the sidestand plug. Another was behind the headlamp, throttle side. Third was on the frame alongside the coolant catch bottle, throttle side.

Replaced the cable tie that had held a knot of wiring behind the headlamp with another that I left a little looser. 

Anyway, the result is the one I wanted (assuming it is not something else that has intermittently cured itself right after I checked all those plugs  ).

Thanks again Speeddog for the support. Helped me believe I wasn't wasting my time. 

[LA]

Remove those pesky baffles and the airbox top.  You can thank me later.

[Moronic]

LA, when running properly she cruises quietly now which I do like. The pipe is an Arrow, so I imagine noisier than Termis with the baffles out. Mufflers certainly seem much shorter.

Maybe one day I will pull them and open the airbox. However, the hp boost my guys got over stock using Tuneboy matched the dyno run shown on bikeboy for the DP full kit, so there is no shortage of go.

They said that if I'd done the airbox and baffles also, they'd have got past the 130hp mark easily. Nice to learn, given it had 30K miles.


On a less satisfactory note ... the poor running is back.    Took her out for a 200km test run Monday night and she lasted a bit more than half distance before the roughness etc returned.   

So, not sure where to go now.

Have been in touch with the workshop and they say they are chockas till after Christmas. Said I could replace the pressure sensor but that they have had a bike in where the problem was a broken wire and the sensor was fine.

So it looks like I am stuck with a poor running bike for a month, or could risk the purchase price of a sensor.

At least I can be sure it is not the tune itself causing the problem.

Thoughts very welcome but probably not much you can say. Needs a check from a diagnostic tool, presumably.

[dbran1949]

I won't be much help with the general problem but the "Still a few stumbles around 2k and 2 per cent throttle" issue will probably never go away. I have the full DP kit on my S4RS and the bike runs very strong except for that one range which is just the nature of the beast I think. Other than that my only problem is keeping the front wheel down under hard acceleration

[Moronic]

Thanks for the info. I'll admit I was assuming the DP ECU had that aspect sorted, perhaps by retarding the ignition a bit in that area of the map.

I've replaced the air pressure sensor but the problem persists. Interestingly, it is becoming more intermittent rather than less - that is, the bike runs well more often. To me that suggests an earthing issue rather than a failed part. But what do I know.

I've an appointment with the workshop next week. With some luck, a diagnostic tool will throw up an error somewhere and we can sort it quickly.

Will update then.

[Moronic]

Well the upshot, peculiarly, seems to be that the poor running has been connected with my use of the local super-premium petrol. Peculiarly, because I have been running this fuel in the bike almost exclusively on the stock ECU and exhaust for 50,000km with no problems whatsoever.

Nevertheless, when I took the bike in yesterday for diagnosis the system showed no fault history at all. They recalibrated the TPS and the new air pressure sensor I had fitted, just in case it helped, and sent me off to try it with the suggestion that if it didn't help, I fill the tank with the lowest-rating petrol available here.

Well, the tweaks made no difference, but after filling an almost empty tank with the different fuel, the bike came good over the next 3km and has been good since.

I am a bit shocked this bike with 11.5:1 compression will run without pinging on the local base-grade fuel, but it seems to. Suppose it helps that Ducatis won't take much throttle at low rpms in any case.

Early days as I have only run through a single tank.

If anybody has a theory about why fitting an Arrow full-exhaust and remapping the ECU would make the motor extremely sensitive to fuel additives I'd be glad to hear it.

It wasn't just a bad fill of the super-premium that had led to the problem. I'd used probably 20 fills of it drawn from various parts of the state with the new tuning, with consistent poor running.

One possibly relevant tidbit: the first time (prior to yesterday) when I noticed the motor suddenly come really good on a trip, was just after I had refuelled. Only thing is, I am pretty sure I had refuelled with super-premium. It was however at a fairly remote rural fuel station.

The shop i use - Pro Twin in Perth - has not developed a solid explanation for this phenomenon. But said they had noticed it on a range of bikes that had come in running poorly, beginning with a bevel motor. After tearing their hair out looking for the problem, they had suggested the fuel and that had done the trick.

Thoughts welcome.

[dbran1949]

does anyone know if the Ducati has a knock detector that automatically retards the timing?

[Speeddog]

does anyone know if the Ducati has a knock detector that automatically retards the timing?

No knock sensors on Ducatis.