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Discussion Starter #1 (Edited)
Hi All,

I am having a missfire issues when i blip the throttle from idle when the bike is at temperature only.
The bike starts well from cold, throttle response sharp until it warms up.

I think i have this issue since the bike has be fitted back with OEM exhaust and EEPROM.

What i did alredy and didn't help:

- Checked air temp, water temp, pressure sensors resistance when cold and warm -> ok
- Check harness wiring up to ECU -> Ok
- Checked Throttle body resistance -> Ok
- Did the throttle body setup procedure of service manual -> Ok
- Balanced both cylinders as indicated i the service manual -> OK
- Set the idle using the bleeders from fully closed up to correct idle rpm -> ok (1.5 turns from close)
- Set the mixture pot of 1.6 ECU according to the 1/3 turn anticlockwise from lean stumble point (I do not have the CO meter)

I can see that the bleeder setting has somehow a slight inflence of the misfire but cannot find the sweetspot.
Also the mixture pot has little influence of this misfire behaviour. What might give you a clue is that i cannot reach the stumble point with the mixture pot on the rich side..

I don't know what more to do at this point and would like to ask your advice as last chance before i have to walk in a ducati workshop.

Here the video:
The warmer the bike the worse the missfires. If i hold the idle above 2000 rpm the throttle response is good.

Am i missing something in the sync/mixture setup (is it so complicted to setup??) ? Any suggestion on what to check more ?

Cheers
 

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First thing to do is to check the battery and the grounds. My 916 runs like absolute shit if I am not getting 13.5 from the batt.

Re your set up, I believe that the injection system is open ended meaning that it will not automatically adjust to a change in intake or exhaust. There are guys smarter than me on this site who know this particular stuff a lot better than I. @ducvet is one of them. Be patient, the answer is here.
 

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Discussion Starter #3
Thanks for the hint. I am indeed using a ligthweight lithium battery and i am reading 13.2 Volts engine turned off, can this be the issue ? How high is the OEM battery voltage ?

Weird stuff is that it only happens when warm !
 

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Battery type makes no difference, check the connection on your coolant temperature sensor, (not the fan switch)
Sounds like its staying rich due to lack of signal from the sensor to the ecu.
Check the chip is seated properly with no bent pins seeing as you've swapped the exhaust and chip back to stock.
 

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Discussion Starter #5 (Edited)
Thanks.

No luck that has been already checked..:|

When the bike is too rich at startup when cold it run smooth.
If it would stay too rich when warm and i would lean it using the mixture pot it should improve. But it doesn't. I tried until it stumbles on the lean side, no luck to make it better.

Really weird issue though..maybe related to ignition after all if the mixture doesn't influence that much..Maybe a bad plug..
 

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Trim pot has a negligible effect on anything beyond idle or a cracked throttle, like at cruise speeds. Think of it as a pilot screw / jet (in combination with the bleed screws) from carb days. If it is going really rich when it's warm and you're sure the TPS is set correctly and all the sensors have tested good, try refitting your old EPROM since the problem started after you changed it back. If no change, may be time to get your hands on a second ECU to test.

It seems it's going really rich in the vid, but is that what you think is happening? Plugs show dark, sooty exhaust, eyes watering in the garage??? Doesn't seem like it should be the case since you say it runs OK when cold, but worth checking for blockage in the original exhaust you installed. Intake blockage as well. Maybe a family of mice built a house in there...
 

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Discussion Starter #7
Trim pot has a negligible effect on anything beyond idle or a cracked throttle, like at cruise speeds. Think of it as a pilot screw / jet (in combination with the bleed screws) from carb days. If it is going really rich when it's warm and you're sure the TPS is set correctly and all the sensors have tested good, try refitting your old EPROM since the problem started after you changed it back. If no change, may be time to get your hands on a second ECU to test.

It seems it's going really rich in the vid, but is that what you think is happening? Plugs show dark, sooty exhaust, eyes watering in the garage??? Doesn't seem like it should be the case since you say it runs OK when cold, but worth checking for blockage in the original exhaust you installed. Intake blockage as well. Maybe a family of mice built a house in there...

Thanks for this suggestion. When warm it doesn't smell that much benzin (like when starting cold) so i don't think it runs so rich ! The bike is still very much ridable without backfire whatsover while driving.. I'll try to fit again the ultimap EEPROM as I have the original in right now and check exhaust. I went from a race exhaust to OEM back. No chance for the mice nest neither ;-) I'll spend a bit more time on the bike this weekend..
 

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Sorry, I have no idea :/ Never heard of a p-regulator out of order on a duc.
Has anything been done to the bike lately?
The trimpot mentioned has a huge effect at low revs, if you just breathe on it itll turn one percent in co, could be it if the bike was tuned for the non oem eprom and had the oem installed after.
 

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Discussion Starter #10
Hi,

I've just done a oil change, filled the tank with new fuel.

Trying to figure out this systematic problem when it warms up I have disconnected the water temp sensor while running. Doing that the engine does even more these misfires.

If i disconnect the temp sensor do you know if the ECU defaults to cold or warm ?

If it defaults cold then i guess i am running much too rich I guess.
Runs well when cold, probably already on the rich side then goes much too rich while it warms up, right ?

Funny thing is that if i would be already very rich then I would manage to reach the rich stumble point with the mixture pot easily but I cannot reach it ! It is somehow contradictory to me.

Next i was thinking to check:

1st Borrow a CO meter to set this mix pot properly. May be sensitive but i don't belive the issue is there as i would have found the sweet spot already.

Then

- Fuel pressure
- Try without air filters (was cleaning them and spray with air filter oil, maybe i clogged them..)
- Check OEM exhaust if somehow restricted..
- Swap the eprom

makes sense ?
 
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