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Discussion Starter #1
My new (to me) 2004 ST3 runs rough, kind of spitting/stuttering, below 3,000rpm, even when the throttle is closed. Otherwise, it seems to run great. Another thing that may be related is that it idles at 1,500rpm and I wonder if the TPS needs to be reset or the "trim" adjusted. Does anyone have any recommendations on how I can correct this condition? Any suggestions would be appreciated.
 

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Welcome to the forum Ljskot999!

Since the bike is "new to you" I would start with a fresh tune. These bikes will run beautifully, but you have to get to a solid base line first! Start with valve clearance check, then sync the throttle bodies, then adjust the fuel trim with CO meter. Of course, you're replacing the fuel filter and air filter when you do this, may as well pop in some new plugs if they have mileage on them or they look bad.. Once that is done, I'd bet your idle will be fine and you'll notice smoother running.

Ducatis generally don't like to be lugged...below 3,000 rpm...that's lugging. You'll find that the ST3 will run smoother with age...some 10-15k miles. Then, I find, that you can chug around (like passing a police station or a convent or something) at 3,500 and the bike won't complain too much. But they are much happier between 4,000 and 5,000 for poking around, and 5,000 + for spirited riding.

Good luck!
 

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I rode my ‘05 for a couple of years with the same stumble as you describe. Do some searching and you’ll find several threads on the subject. It had surging, trailing throttle roughness, general choppiness. Once above 3500 or so it cleared up. I decided to try a ECU reflash (Rexxer) at one of my major service events and bam! Best extra $300 I’ve spent on it.
It runs the best it ever has, I can chug down to 2500 rpm in top gear. Putt thru town at 2-3000 rpm smooth and steady. It’s what worked for me, YMMV, good luck.
 

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Discussion Starter #5
I rode my ‘05 for a couple of years with the same stumble as you describe. Do some searching and you’ll find several threads on the subject. It had surging, trailing throttle roughness, general choppiness. Once above 3500 or so it cleared up. I decided to try a ECU reflash (Rexxer) at one of my major service events and bam! Best extra $300 I’ve spent on it.
It runs the best it ever has, I can chug down to 2500 rpm in top gear. Putt thru town at 2-3000 rpm smooth and steady. It’s what worked for me, YMMV, good luck.
I've been researching a place where I could investigate an ECU reflash for my ST3. It sounds like you had the same problem that I am experiencing and a Rexxer reflash did the trick! Fortunately, there is a place in Sacramento, CA (about 50 miles from me) that is on the "Rexxer" dealer list. I am going to check on this in the morning. Thank you, very much!
Welcome to the forum Ljskot999!

Since the bike is "new to you" I would start with a fresh tune. These bikes will run beautifully, but you have to get to a solid base line first! Start with valve clearance check, then sync the throttle bodies, then adjust the fuel trim with CO meter. Of course, you're replacing the fuel filter and air filter when you do this, may as well pop in some new plugs if they have mileage on them or they look bad.. Once that is done, I'd bet your idle will be fine and you'll notice smoother running.

Ducatis generally don't like to be lugged...below 3,000 rpm...that's lugging. You'll find that the ST3 will run smoother with age...some 10-15k miles. Then, I find, that you can chug around (like passing a police station or a convent or something) at 3,500 and the bike won't complain too much. But they are much happier between 4,000 and 5,000 for poking around, and 5,000 + for spirited riding.

Good luck!
Hi Mike, thank you for your suggestions. I will check on getting these done. Thank you!
 

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Your idle at 1,500 rpm is a bit high. Mine had been around 1,000 for several years but I had frequent stalling when cold. During my most recent service earlier this year, a new mechanic I took it to bumped it up to 1,250 and that has been the solution to resolve my stalling issue (or at least a contributor to solving it). He showed me the idle spec from Ducati ...they suggest around 1,250 so you might want to bump yours down a bit. Re: the lugging, I think these engines just don't like to run on the slower side. I had the same lugging issues for years ...I've done all the tuning and ECU reflashing, etc., etc. and my bike still stumbles at lower rpms. It runs fantastic at 4,000+.
 

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Discussion Starter #9
what's the chain like? solved a few running issues with a new chain over the years. gearing?
I have heard of a connection to chain issues. The chain has 7,000 miles on it. I believe that the chain is a little tight and I plan to readjust it once the weather improves. Thank you for that suggestion. It would be great if that was the fix!
 

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We had 2 STs, a 2004 ST4s and a 2006 ST3s. Both bought used with very low miles (both under 1000 miles). Both had the DP pipes and airbox that was sold as a kit that purportedly included a "race" ECU (although it turns out that the "race" ECUs were not available for some time and were not replaced when the Kit was installed on a lot of ST bikes). Both ran like crap under 3,000 rpm as described by Janky59 and allegedly had the "race" ECU. However, upon hooking the bikes up to the dealer's Official Ducati Diagnostic computer, we discovered both bikes still had the stock ECU. Long story thereafter, but when the stock ECUs were replaced with the "race" ECUs, all of rough running, dying and running like crap under 3,000 rpm were magically fixed.

I put 40K miles on the ST4s and my lovely wife put 78K miles on the ST3s thereafter with no low rpm or other related issues It won't cost you much to have the dealer check it out, particularly if you are going to have a fresh tune-up (and I agree, this is also a very good idea).

BTW, I added a Power Commander IV to the ST4s before I replaced the ECU and it did not solve the low rpm problems, but did pickup a few extra HP at higher rpms. Frankly, I would not spend the money on the PC if I had it to do over.

This all happened in 2007 when there was no technology to re-flash the stock ECU, so both had to be replaced with the "race" ECU. I cannot speak to the current ability to fix this issue by re-reprogramming the stock ECU to the "race" ECU mapping as suggested by Janky59, but conceptually this should also fix the problem at much less expense than replacing the ECU. I really don't think anything else will fix it.

STs are gone now and we are both riding 2017 SuperSport S bikes. Love the new bikes, but miss the ST's wind protection.
 

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Discussion Starter #11
We had 2 STs, a 2004 ST4s and a 2006 ST3s. Both bought used with very low miles (both under 1000 miles). Both had the DP pipes and airbox that was sold as a kit that purportedly included a "race" ECU (although it turns out that the "race" ECUs were not available for some time and were not replaced when the Kit was installed on a lot of ST bikes). Both ran like crap under 3,000 rpm as described by Janky59 and allegedly had the "race" ECU. However, upon hooking the bikes up to the dealer's Official Ducati Diagnostic computer, we discovered both bikes still had the stock ECU. Long story thereafter, but when the stock ECUs were replaced with the "race" ECUs, all of rough running, dying and running like crap under 3,000 rpm were magically fixed.

I put 40K miles on the ST4s and my lovely wife put 78K miles on the ST3s thereafter with no low rpm or other related issues It won't cost you much to have the dealer check it out, particularly if you are going to have a fresh tune-up (and I agree, this is also a very good idea).

BTW, I added a Power Commander IV to the ST4s before I replaced the ECU and it did not solve the low rpm problems, but did pickup a few extra HP at higher rpms. Frankly, I would not spend the money on the PC if I had it to do over.

This all happened in 2007 when there was no technology to re-flash the stock ECU, so both had to be replaced with the "race" ECU. I cannot speak to the current ability to fix this issue by re-reprogramming the stock ECU to the "race" ECU mapping as suggested by Janky59, but conceptually this should also fix the problem at much less expense than replacing the ECU. I really don't think anything else will fix it.

STs are gone now and we are both riding 2017 SuperSport S bikes. Love the new bikes, but miss the ST's wind protection.
Thank you for your suggestion on the ECU as being a possible culprit for my ST3's low rpm problems. It is an area that I have been examining carefully. I have heard about the "race ecu" you are talking about. I wish that I could use one of those ECUs. Unfortunately, they are for 2006 and later models and my is a 2004. In January of 2005, Ducati issued Service Bulletin SVC-05-001 for early model 2004 ST3s (like mine) that included a new ECU with part# 28641001L that was part of a solution for a low speed issue. Mine has this ECU so I stopped pursuing this service bulletin. Next week, my ST3 goes in for a valve clearance check, timing belt change, TPS check, and trim adjustment. My fingers are crossed that this servicing will be the solution to my problems.
 

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Thank you for your suggestion on the ECU as being a possible culprit for my ST3's low rpm problems. It is an area that I have been examining carefully. I have heard about the "race ecu" you are talking about. I wish that I could use one of those ECUs. Unfortunately, they are for 2006 and later models and my is a 2004. In January of 2005, Ducati issued Service Bulletin SVC-05-001 for early model 2004 ST3s (like mine) that included a new ECU with part# 28641001L that was part of a solution for a low speed issue. Mine has this ECU so I stopped pursuing this service bulletin. Next week, my ST3 goes in for a valve clearance check, timing belt change, TPS check, and trim adjustment. My fingers are crossed that this servicing will be the solution to my problems.
Hi. I have owned my 2004 ST3 for 6 years now - it’s been a hate/love relationship. After a full $$$ service (35k km), it still didn’t run well below 4k rpm. I decided that Ducati ownership was only possible by learning how to service it. I learnt how to adjust desmodromic valves, replace valve return springs, update the ECU mapping and tune the EFI. Good news, after 2 yrs of ownership it now runs better in city; was always good on country roads. I recently nailed EFI tune, with an excellent result of low rpm (2k+) smooth throttle roll on/off. With 54k km and it running better then ever, I just replaced steering and front wheel bearing and have a new clutch and cam belts ready to replace as per service interval. Interested to know if the trip to the mechanic helped.
 

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Discussion Starter #13
Hi. I have owned my 2004 ST3 for 6 years now - it’s been a hate/love relationship. After a full $$$ service (35k km), it still didn’t run well below 4k rpm. I decided that Ducati ownership was only possible by learning how to service it. I learnt how to adjust desmodromic valves, replace valve return springs, update the ECU mapping and tune the EFI. Good news, after 2 yrs of ownership it now runs better in city; was always good on country roads. I recently nailed EFI tune, with an excellent result of low rpm (2k+) smooth throttle roll on/off. With 54k km and it running better then ever, I just replaced steering and front wheel bearing and have a new clutch and cam belts ready to replace as per service interval. Interested to know if the trip to the mechanic helped.
Well, after having the valve clearances checked, the timing belts changed, the throttle bodies synchronized, the trim set to 3% of CO, the idle screws being properly set(it now idles at 1200rpm), and new Iridium spark plugs the ST3 runs betters and the fuel economy looks to have improved. The low speed stumble has been reduced, but it is still present. I still don't know whether the exhaust valve returns springs were every replaced by the previous owner so it is possible to be a potential cause. Next, I plan to check out the ignition coils and spark plug wires and see if they are up to spec. Does anyone know what the primary/secondary resistance values are for the BERU 0 040 100 050 (part # 380.4.010.1c) should be? I purchased a used one from ebay and it values are 0.8 ohms/15.09 K ohms. From what I've read, the 0.8 ohms resistance is a bit high for the primary side, but that doesn't mean that it is faulty. I also plan to clean and use dielectric gel on all secondary connections to make the electrical connections as optimal as possible. I may be grasping at straws, but I am determined to get this issue solved.
 

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They all run like crap below 4K. If the weather is cool, not a problem, however in the warmer months, any stop and go city stuff will more than try your patience. Most people go for an ECU reflash.
 

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General specs is less than 12k ohms per foot for spark wires.They do state that some manufacturers can be higher though.
I'm a great believer in dielectric grease too.
 

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Discussion Starter #16
General specs is less than 12k ohms per foot for spark wires.They do state that some manufacturers can be higher though.
I'm a great believer in dielectric grease too.
The four used plug wires that I have for comparison purposes are all under 5k ohms. Today, I find out how the ones on my ST3 compare along with the coils. I'm hoping to find the gremlin that has been eluding me so far.
 

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i'd be very surprised if it was any sort of coil, etc, issue. they just don't give issues.

was the idle mixture clean or dirty? dirty is high hc and o2. if it's dirty, it hasn't had the closing springs done, or has valve sealing issues if it did.
 

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Discussion Starter #18
This is an update to an old post. To review, I have done a lot to try to resolve this issue. I have put about 2,000 miles on this ST3 and had a revelation yesterday as to what the problem really is. At first, I felt that the poor performance was most at 3,000rpm or less. I now observe that that is when the problem is most noticeable. I suspect that the stutter is at low throttle opening that is easiest to experience at low speed. I have noticed that at higher engine speed a more subtle sutter when the throttle is barely open. With this new information, does anyone have any ideas as to how to resolve it? Could the TPS have any influence or fuel pump pressure, or a low charging voltage?
 

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First off, the engine is not going to like cruising around below 3,000 rpm...period. I've found that a well tuned ST3 engine can go as low at 3,500 rpm if cruising around on level...but I'm typically in the 4,000 to 5,000 rpm range. Is it stumbling below 3,000 rpm when in neutral and just manipulating the throttle? What year bike? In '06 Ducati switched to a closed loop system with a lambda sensor. The '06 and '07 bikes have driveability issues at low rpm attributed to their lean mapping. If you are consistently getting a "stutter" at a particular throttle opening, you may want to check your TPS. It's a rheostat that can develop a rough spot. You can check it with diagnostic software like ScanMX5 or the others.
 

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Discussion Starter #20
First off, the engine is not going to like cruising around below 3,000 rpm...period. I've found that a well tuned ST3 engine can go as low at 3,500 rpm if cruising around on level...but I'm typically in the 4,000 to 5,000 rpm range. Is it stumbling below 3,000 rpm when in neutral and just manipulating the throttle? What year bike? In '06 Ducati switched to a closed loop system with a lambda sensor. The '06 and '07 bikes have driveability issues at low rpm attributed to their lean mapping. If you are consistently getting a "stutter" at a particular throttle opening, you may want to check your TPS. It's a rheostat that can develop a rough spot. You can check it with diagnostic software like ScanMX5 or the others.
Hello Mike,
This is an early 2004 ST3 without catalytic converter. I am not talking about cruising at 3,000rpm. It's mostly noticeable when backing off on the throttle to slow down. I typically cruise between 4000-5500rpm. When in neutral I have noticed a miss when revving up off of idle. I don't remember the exact engine speed, but I will check later today and check. Thanks for the tip on TPS "rough spots" as it is the area that I am focused on. One question, the TPS was set my a mechanic in January. Could a TPS be properly set yet still have a rough spot? Thanks for you comments on this issue!
 
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