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Discussion Starter #1
I need help diagnosing a problem I'm experiencing with my 2001 996. I'm not sure how much information to provide; please excuse me if I provide too much and please don't hesitate to ask for more if what I provide is insufficient.
The Problem: surging on constant, low rpm throttle at mainly lower speeds of say 50-70km/h. Surging can be quite pronounced at times all the way to being not very noticeable at other times. Like I say, its most noticable at lower speeds, but can also be noticed at higher speeds as well of say 100-120km/h, always at constant throttle. Pulls strongly and cleanly through the rev range when I'm hard on the throttle.
Potentially pertinent info: running slip ons, single injectors with stock 916 chip. Just installed Pistal hi comps, this issue was not present before the pistons went in and has been there from the day I picked the bike up with these installed. The bike also underwent extensive servicing while the pistons went in including new engine cases, reconditioned rockers and new cams. Just replaced the fuel filter yesterday with no effect at all.
Thanks so much in advance for any input any of you may have.
 

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Discussion Starter #3
You're spot on with your rpm guesse yellowblur, I can't answer your question though as I'm not familiar with the setup of my bike on that level. That's a level of detail I've left in my mechanichs hands. After the the new pistons had been run in my mechanic did some dyno tweaking and said he now needed a ultimap chip as the 916 chip was not allowing enough fuel.
 

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You're spot on with your rpm guesse yellowblur, I can't answer your question though as I'm not familiar with the setup of my bike on that level. That's a level of detail I've left in my mechanichs hands. After the the new pistons had been run in my mechanic did some dyno tweaking and said he now needed a ultimap chip as the 916 chip was not allowing enough fuel.
I was faced with the same problem after installing the UM222 single injector Ultimap chip and having the dealer “Tune” it for me @ $$$$$$$. Bottom line is it was running way too lean but I only noticed it between those rpm’s -- not right away, but after about 20 min + into a run. Went through the TB’s/Cylinder balance which were off. TPS was set perfect though. The By-Pass screws were out way too far also, helping to cause the lean miss.

If you care to read about it here’s the post: http://www.ducati.ms/forums/showthread.php?t=57491

I think you’ll like the UM222 chip, sure woke my bike up once it was dialed in. :cool:

Good luck with it, hope you get it fixed soon.
 

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Discussion Starter #6
Thx so much for your input yellow blur. I remember "reading" your post at the time and feeling as I do now that alot of the info therein is above my level of experise, but it's a good reference point for communications with my mechanic. Now all I need to do is track down a um222. Anyone got one lying about?
 

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Discussion Starter #7
One more thing I should add that makes me question the lean running hypothesis, is that the fueling was a hundred percent before the pistons went in. Can anyone fill me in on what the knock effects are on the rest of the system by putting in hi comp pistons? Are there any other possible causes of this problem (such as a clogged fuel filter which I've discounted)?
 

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You don't say what the new compression ratio is and I am no mechanic but I would say that you now have a completely different motor from the one your chip is set up for and you need to remap. Is a Power Commander available for your computer?
 

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Discussion Starter #9
You don't say what the new compression ratio is and I am no mechanic but I would say that you now have a completely different motor from the one your chip is set up for and you need to remap. Is a Power Commander available for your computer?
Fairly high, 13.5 to 1.
 

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Discussion Starter #10
Any other input from anyone else. I'm feeling at a bit of a loss here because from my point of view I dropped off a motorcycle that was running great (well, other than a worn out clutch) and then after paying a large (for me) sum of money for the work performed I recieved a motorcycle in return that has a very annoying characteristic that wasn't there previously. So I'm trying to figure out if this is a tuning issue related to the installation of the hi comp pistons which was my decision and I realize is somewhat akin to opening a can of worms and owner beware. Or is it possibly another issue.
What do you guys think? When you pay money for work performed do you expect the bike to be working well when it's handed back, or is it reasonable to continue to pay for ongoing work to sort mystery issues related to the original work performed?
 

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I would find a UM222 and have a good shop put it on the dyno and map it. Why are you using a 916 chip?
 

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Any other input from anyone else. I'm feeling at a bit of a loss here because from my point of view I dropped off a motorcycle that was running great (well, other than a worn out clutch) and then after paying a large (for me) sum of money for the work performed I recieved a motorcycle in return that has a very annoying characteristic that wasn't there previously. So I'm trying to figure out if this is a tuning issue related to the installation of the hi comp pistons which was my decision and I realize is somewhat akin to opening a can of worms and owner beware. Or is it possibly another issue.
What do you guys think? When you pay money for work performed do you expect the bike to be working well when it's handed back, or is it reasonable to continue to pay for ongoing work to sort mystery issues related to the original work performed?
First, it’s not unreasonable to expect things be right when you get it back (reread my thread - I surly wasn‘t happy after spending plenty then ending up having to do it myself to make it right - talk about pissing money away :mad::mad:). Mistakes are made but as long as the person making the mistake steps up to the plate and takes care of it @ no cost, no harm done other then lost time (I was too far away [over 250 miles - rent a van, etc] to return with the negative answers I was getting and didn‘t feel I would be taken care of so I cut my losses). If this was a known problem going into changing to that high of comp pistons (not so sure it is) it may be one of those things that more money is needed to fine tune the problem out. (UM222, Power Commander or?).

What octane fuel are you running? Try the highest you can get if you aren’t already - should be with that comp. (I’m sure that statement will start a flame!) What octane would that be in Vancouver?

It may very well be running too lean as it sure sounds like to me - as you know. It may be the basics need to be gone over again (and where I’d start first) as in all the adjustments rechecked to rule them out. Fuel mixture for sure. The mapping on the 916 chip may be too lean at that RPM for your combination. Apparently that is an area that requires more fuel since mine using the UM222 chip on a stock engine also missed in that same range but wasn’t felt anywhere else, even though it was running way too lean across the board, the exhaust gas analyzer proved this. Just a visual of the left muffler told me that before I even hooked it up (remembering that I found the majority of exhaust gasses exiting the left pipe after the pre-muffs). I used the taps in the pipe for the readings, not the muffs.

Was the 916 chip in it when you brought it in? Do you have the stock chip? If so, try reconnecting the 2 injectors and install the chip. Should have plenty of fuel then to see if the problem goes away. May end up with other issues but just to prove it out.
 

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Discussion Starter #14
First, it’s not unreasonable to expect things be right when you get it back (reread my thread - I surly wasn‘t happy after spending plenty then ending up having to do it myself to make it right - talk about pissing money away :mad::mad:). Mistakes are made but as long as the person making the mistake steps up to the plate and takes care of it @ no cost, no harm done other then lost time (I was too far away [over 250 miles - rent a van, etc] to return with the negative answers I was getting and didn‘t feel I would be taken care of so I cut my losses). If this was a known problem going into changing to that high of comp pistons (not so sure it is) it may be one of those things that more money is needed to fine tune the problem out. (UM222, Power Commander or?).

What octane fuel are you running? Try the highest you can get if you aren’t already - should be with that comp. (I’m sure that statement will start a flame!) What octane would that be in Vancouver?

It may very well be running too lean as it sure sounds like to me - as you know. It may be the basics need to be gone over again (and where I’d start first) as in all the adjustments rechecked to rule them out. Fuel mixture for sure. The mapping on the 916 chip may be too lean at that RPM for your combination. Apparently that is an area that requires more fuel since mine using the UM222 chip on a stock engine also missed in that same range but wasn’t felt anywhere else, even though it was running way too lean across the board, the exhaust gas analyzer proved this. Just a visual of the left muffler told me that before I even hooked it up (remembering that I found the majority of exhaust gasses exiting the left pipe after the pre-muffs). I used the taps in the pipe for the readings, not the muffs.

Was the 916 chip in it when you brought it in? Do you have the stock chip? If so, try reconnecting the 2 injectors and install the chip. Should have plenty of fuel then to see if the problem goes away. May end up with other issues but just to prove it out.

Yellow blur before answering your questions I'd like to thankyou for all the input you've given me through this thread. Thanks for taking the time. Interesting that you mention reconnecting the second injector as that's something that's crossed my mind recently as well. Bike was stock save for Arrow slipons that are still on the bike, when I bought it six (!?, good lord how time flies) years ago. Unfortunately, we (my mechanic and I) did the single injector mod back in '05 and I'm not sure where the stock chip might be. Might have to do some digging on that front. I'm hoping to track down a um222 though as that seems to be the way to go from where I'm at. Have a possible line on one so will keep the fingers crossed.
I am using the highest octane fuel I can get here in BC which is 94octane. Like I say, the input is much appreciated because it allows me to see a way forward in communications with my mechanic. If it's a tuning issue then it's a problem to be tackled in a cooperative fashion rather than a "here, fix this mess you made" kind of fashion!
 

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You are welcome vanduc996; I just hope this is some actual help for you.

One thing you might want to look at and try as a quick test is check to see how far the By-Pass screws are turned out. Take a count of how many turns and seat them completely if not already. I think you might find they are out leaning the mixture too much, mine sure were. That simple change made most the difference I think, however this will change the balance but probably not enough (depending on where it is now) to matter for this test. Bottom them out if they aren’t already and take a ride.
 

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You are welcome vanduc996; I just hope this is some actual help for you.

One thing you might want to look at and try as a quick test is check to see how far the By-Pass screws are turned out. Take a count of how many turns and seat them completely if not already. I think you might find they are out leaning the mixture too much, mine sure were. That simple change made most the difference I think, however this will change the balance but probably not enough (depending on where it is now) to matter for this test. Bottom them out if they aren’t already and take a ride.
I've had a real nightmare with my 996 lately, suddenly went rich and hard to start, ended up doing a full set up of TPS, balance and CO etc, and had lean symptoms which included backfiring on the over run and spitting back thru the airbox after approx 10 miles running.
After all that, I richened it up on the idle trimmer pot (1.6M ECU) and all came good. I measured the CO after this and it's around 6% at tickover, slightly rich really but it gives the best results, so it's staying for now
Good luck with it. Have you considered that the igntion timing might need adjusting now you have HC pistons installed?
Ps/ Agree with much of what Yellow blur says, the bleed screws and pot have a significant effect, but more so at lower end of the revs scale in my experience, ie less than 4K RPM
 

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Discussion Starter #17
I've had a real nightmare with my 996 lately, suddenly went rich and hard to start, ended up doing a full set up of TPS, balance and CO etc, and had lean symptoms which included backfiring on the over run and spitting back thru the airbox after approx 10 miles running.
After all that, I richened it up on the idle trimmer pot (1.6M ECU) and all came good. I measured the CO after this and it's around 6% at tickover, slightly rich really but it gives the best results, so it's staying for now
Good luck with it. Have you considered that the igntion timing might need adjusting now you have HC pistons installed?
Ps/ Agree with much of what Yellow blur says, the bleed screws and pot have a significant effect, but more so at lower end of the revs scale in my experience, ie less than 4K RPM
My trust in my mechanic, admittedly, is such that when everything is running fine I don't question his expertise at all. Now that there's an issue, well..... I'm sure that he has adjusted the ignition timing if that's a necessary adjustment to make with hi comps. That being said, that's exactly the kind of info I'm looking for to run past my mechanic just to make sure that all the bases are covered. Thx for the heads up on that issue.
 

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I've had a real nightmare with my 996 lately, suddenly went rich and hard to start, ended up doing a full set up of TPS, balance and CO etc, and had lean symptoms which included backfiring on the over run and spitting back thru the airbox after approx 10 miles running.
After all that, I richened it up on the idle trimmer pot (1.6M ECU) and all came good. I measured the CO after this and it's around 6% at tickover, slightly rich really but it gives the best results, so it's staying for now
Good luck with it. Have you considered that the igntion timing might need adjusting now you have HC pistons installed?
Ps/ Agree with much of what Yellow blur says, the bleed screws and pot have a significant effect, but more so at lower end of the revs scale in my experience, ie less than 4K RPM
With mine the CO was 1% to 1-½%. Except for going through the whole process as is really needed for fine tuning (Bal, TPS, etc), what I found made the most significant change in mixture was the By-Pass screws. So much potential there. I fully richened the mixture with the trimmer pot which effects both cylinders equally in theory, and overall does, but is to be used to set the mixture desired with both By-Pass screws completely closed. I never got the engine running correctly using just to pot because my By-pass screws were open too far. The way I interpreted the manual (and the way it’s stated along with the way is had been adjusted prior to me) the By-Pass screws were to be used for idle speed. That is Wrong! The throttle stop screw is used to set idle speed. The By-Pass screws are for mixture balance between cylinders - adjusting the stop screw for idle speed.

Usually one cylinder will be richer from the optimum setting since you should be taking your reading from the leanest cylinder and making that your base setting - since you can only richen BOTH cylinders with the trimmer Pot. So in order to equal the mixture in both cylinders the By-Pass screws come in, allowing more air in leaning the mixture out in that ONE cylinder through the complete RPM range (not considering chip mapping in this portion of tuning) not just below 4K.

Actually 6% is within the “Performance” range of the settings - necessary? Hard to say because it does seem a bit on the fat side to me. - although safer then too lean. I have to question if running that rich was really necessary since too rich does degrade performance but does also cool the cylinder. Unfortunately it also adds excessive deposits and can also wash the cylinders of lubrication if too excessive. Overall - I’m sure there’s no reason to loose sleep over it.

Edit: Forgot to mention. The Trimmer Pot ended up exactly where it was when I started when I had the miss, Mid Point of the adjustment. That’s how much difference the By-Pass screws made.
 

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the air bypass screws and idle trimmer work in similar ways, especially at low throttle openings. you can just play with them too - wind the air bleeds in for richer. they should only be a turn or so out i'd think. i use them to balance the idle mixture in each header, as the report below lays out.

the full throttle body set up routine is laid out here - http://www.bikeboy.org/ducati4vthrottleb.html and there's idle trimmer recommended settings in my eprom products page.

the UM222 is based on the 916 eprom, which has less wot ignition advance than the std 996 eprom anyway. i don't recall if i limited mine to 37 or if it still goes to 39, but it should work just fine for what you have. eprom map changes are the only way to adjust ignition advance.

more comp itself doesn't usually change fuelling requirements that much if at all, but a lean idle mixture setting could easily give the issues you're having. if they've done anything different with cam timing this could also cause an issue, but i wouldn't go it as the first suspect.
 

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Discussion Starter #20
the air bypass screws and idle trimmer work in similar ways, especially at low throttle openings. you can just play with them too - wind the air bleeds in for richer. they should only be a turn or so out i'd think. i use them to balance the idle mixture in each header, as the report below lays out.

the full throttle body set up routine is laid out here - http://www.bikeboy.org/ducati4vthrottleb.html and there's idle trimmer recommended settings in my eprom products page.

the UM222 is based on the 916 eprom, which has less wot ignition advance than the std 996 eprom anyway. i don't recall if i limited mine to 37 or if it still goes to 39, but it should work just fine for what you have. eprom map changes are the only way to adjust ignition advance.

more comp itself doesn't usually change fuelling requirements that much if at all, but a lean idle mixture setting could easily give the issues you're having. if they've done anything different with cam timing this could also cause an issue, but i wouldn't go it as the first suspect.

Thanks for that info regarding the compression change Brad. That aspect has confused me the most, or has been my largest question, because as I indicated earlier, she was fueling sweetly (at least as far as I could feel for the state of tune she was in) before the pistons went in.
The cam timing has indeed been adjusted (all work since I've owned her, essentially from new, has been performed by the same well respected mechanic), but as far as I'm aware, only from "as delivered" to "as intended" or factory spec. I'm not 100% on that though. Thanks again for weighing in with that helpful info:)
 
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