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63 Posts
Discussion Starter #1
I just made the worst decision possible. I had an acquaintance come by to tune my 2001 996 with Termi half system and Ducati chip for such system on recommendation from a friend. Now, it is about to blow up.

On start it pops up to 4k rpms, comes down to about 3k and starts backfiring out of the vertical cylinder.

To start. I had just finished putting together my 996 after having the engine worked on caused by a bad tranny. Since that was out I thought it feasible to have the frame repainted because the acid burns from nondesirable acrobatics that required a first cosmetic rebuild. This is second.

I had put the bike together a week ago but it was running just right. I thought it was the fuel injection because I had the cams degreed. The bike had always run well so I assumed it was this adjustment.

Since I do not feel comfortable messing with the fueling system I planned to take it to the mechanic that did the engine work. Common sense told me it would be best.

Friend said he knew of someone that I have met before that was quite skilled with Ducati's, having stripped and rebuilt his previously.

After receiving an email from the mechanic that I would have to schedule (expected) with the service manager I thought it would be quicker to get friend of friend to do it.

Shh, don't spoil it for everyone if you know where this is going.

The gentlemen was kind enough to make time because he is a Ducati lover and a good guy.

Well, he started off with setting the TPS and syncing the throttle bodies but there was an issue with the CO output for setting the trim.

It ended up being the horizontal cylinder was firing. We were trying to figure out why. He is good friends with the mechanic that worked on my engine so he contacted him for leads to the problem.

It looked to be a wire so another friend that specializes in such things offered to change it. Before acting he double checked everything and found that the brake sensor connector for the rear brake and the connector for the coil were the same. From this he deduced that I had reconnected them improperly when building bike back up. Whew! Easy fix.

Friend of friend came back today, good guy, to finish the tuning.

He could not get it to run right and set it the best he could, running as mentioned.

I took it for a test ride and it was dangerous. I opened up the throttle and it stayed there until I pulled in the clutch and gave it a little gas. No engine braking and idling through turns at 4k rpms. Very disconcerting.


- Starting with a 4k idle and then dropping to 3k with backfire after backfire.
- When ridden throttle bike idles at 4k until clutch is pulled in and a little gas is given then idle drops to 1k.

I would love to just return it to original settings since the running problem I had was my error of connecting the rear brake switch with the coil and vice versa.

The bike always ran well before, though a little rich. I would expect the same now. I did plan to have the FI checked just to make sure all is in order. After spending $2k on the engine another $100 or two to make sure things are in perfect running order isn't that significant.

Ah, taking the quick way has left teeth marks on my rear.

The best thing to come of this is that my knowledge has increased though I am not comfortable with fueling systems yet.

I would think the problem is the TPS since it was most likely set when the engine was running on the one cylinder as were the throttle bodies.

Thank you for any help Ducati oracles. This has to be the worst I have ever seen a bike run. Sadly, it is mine and I allowed it to be done to her.

63 Posts
Discussion Starter #3
Thank you for the tip. I think there is one connector that splits to both but I will check that tomorrow.

We were checking all the sensors and all seemed good.

Nothing worse than wasting time going the wrong way.

Ah, c'est la vie.

It is not the first nor will it be the last time.

63 Posts
Discussion Starter #5
I checked the injectors could not have been crossed because there is one plug off the harness for all four. Thank you for the recommendation.

The vacuum hoses don't seem to be the issue either.

Sadly I was informed by a friend that is a certified car mechanic that the backfire I was getting in the throttle body could not be caused by the injector system. He said it most likely involved a valve being open too long.

I plan on making an appointment to have the mechanic that tore apart and put together my engine. He's a well respected engine builder so I would assume he set everything up properly and would know whatever adjustment would be need to fix the issue.

I'll pass along the final result.

To overcome the explosive nature of the setting I was left with I decided to delve into the system myself, with caution.

I started off with adjusting the idle down just above 1k rpms. The gentlemen trying to tune my system would allow the bike to immediately idle at 6k rpms which made me extremely uncomfortable. To me it is rocker arm abuse that should not occur. I thought it was normal practice to build up rev's to avoid unnecessary wear on the dry rocker arms.

Then I checked the individual mixture screws. The were set completely closed. I took them out a 1/4 turn and saw how it affected the system. I was getting throttle body backfires so I did another 1/4. It seemed to improve the the running with only exhaust backfires.

I let the engine warm up to 180 degrees.

I decided to set the trim to zero now. Yes, I probably should have started with that.

I opened the mixture screws another 1/8 turn.

This is where I ended up after going back down trying to fine tune.

I turned the trim back about a 1/4.

This seemed to give me the best temporary, uneducated setting. Occasional back fires only occurred. It idled between 1k and 1.1k.

I took the bike for a spin and it felt tremendously better, not like the earlier death trap.

Later I took it a few miles to a friend restaurant for espresso. It ran quite well. I did see the added power indicated it was time for new clutch plates for there was a little slipping under hard acceleration.

On the way back from the cafe I did get some minor rear backfires and then what felt like dreaded throttle body backfires.

I will try to do a little fine tune so I can comfortable baby her to the building mechanic 100+ miles away.

I'm hoping for a leisurely morning ride up followed by a aggressive scenic ride back.

I'll post what the final result is, hopefully nothing dreadful.

Ah, so close to having my girl back.


331 Posts
I can only guess that the place you are taking it too is also a Duc dealer? If so, I am fairly certain I know which one. If it is the same, I can tell you what I was told about getting cams degreed. Your fuel settings will be much different than what they were before. I would also suggest not ridding the bike up to get it worked on. Go rent a trailer or truck from U-haul. If something is wrong with the valves, you are only going to be doing damage the more you ride it.

63 Posts
Discussion Starter #8
Thanks L4V.

Yes, Kawtipping they are a Ducati dealer and I'm sure you know them. They are closer to you than to me.

If I can't get her running smoothly I will borrow a friend's trailer. Accentuating the problem would not be in my best interest. It would equate to more time and money wasted.

Actually, I probably shouldn't ride it at all in case the mechanic had an off day. Hey, it happens to everyone. With my luck he would have one while working on my girl.


11,256 Posts
I too immediately think its the timing because its a variable that can easily cause that problem, but I'm not 100% sold on it yet.

One test I do all the time is to try running the bike on each cylinder, separately. So... pull the injector's and spark plug for one cylinder and see if it runs. Its a good way to determine which cylinder is "bad" and which is OK.

How did the bike get tuned? Was it a simple CO adjustment, or did the bike go to a dyno and you have a new EPROM or PC3?

Vacuum hoses are probably not the culprit. I ran both of my 748's without them AND w/o blocking the holes for quite sometime with no consequences.

TPS adjustment effects BOTH cylinders, so if you do my test above with testing the individual cylinder's, then you can easily figure that one out.

Finally; severely poor clearances and very low compression (IE; valves not seating properly) can cause the issues your talking about.

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63 Posts
Discussion Starter #10
Thank you for the recommendation Tye.

The gentleman tuning it first adjusted the TPS (I don't know how. He is the silent type.). From there he balanced the throttle bodies and then tried setting the CO mixture by reading the exhaust gas using a gas reader. He had no luck.

No. It was not tuned on a dyno.

Yes, that is what my friend that is a mechanic said.

I am trying to get in to the mechanic that worked on the engine. Last night I sent an email to the service department and this morning I called. Since I didn't get a response back I called again and received an apology was told I would get a call in the morning.

Apparently the mechanic had a mishap with his truck..just after paying it off. Poor guy...unless he has great insurance.

That will probably make it tougher on me to get in since it most likely put him behind schedule.

She is so close to being ready to run I can taste it.

This evening we went to drop of the GSXR750 for another friend to get acquainted with her for our trip to the Gap. (He has a 998 race bike but has ridden yet this year.)

The run out to the burbs was excellent. Just enough traffic to keep it interesting but to not slow you down. My buddy was stretching the legs of his R32 so I had to open up the Suzi. Ai, ya, yi! The 750 is an incredible bike. Effortless acceleration and so easy to ride. The comfort is of a sport touring bike in my opinion. Very impressive.

Ah, it will be so nice when my lovely torture rack is doing her healthy deep rumble.

724 Posts
It sure sounds to me like the TB’s and mixture are not quite dialed in yet. Any time the by-pass screw settings are changed, so is the balance and mixture, and it doesn‘t take much. There is a lot of potential just in the TB’s. When adjusting balance, it helps to balance the TB’s at idle just to get them close, then check bal at a higher rpm (say approximately 3000 rpm) and work to match them there. (Don’t try holding it there while adjusting it). Most likely you’ll see a difference in readings. Once even at the higher rpm, don’t be concerned with the reading at idle. It’s more important they are balanced where the engine will be used (within reason) and not stopped at some signal, as long as it idles at the correct rpm.

Also, it’s worth the time it takes to get the TPS set @ the perfect voltage with the butterflies completely closed, then bring it up to the “Start” idle (reference) voltage, then adjust the idle screw to set the idle speed not worrying about where the voltage ends up, NOT by using the By-Pass screws. It doesn’t matter if the by-pass screws are shut completely, they are there to “Fine Tune” and match the mixture of the individual cylinders -- but remembering that if you open one up it will change the balance along with leaning the mixture in that cylinder and you‘ll have to go back and readjust balance, while the trim screw in the computer affects mixture in both cyl’s equally.

The only way to really get the mixture right is to use an exhaust gas analyzer, but you need to use the taps in the individual pipes. The blend of exhaust is not equal after the pre-mufflers and the majority of exhaust favors the left muffler..

Hope this helps some. Here is something you may want to glance at.

Hope you get it running like it should. :)
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