"cough" at 3k rpm and then dead - s4r

[♣ McKraut ♣]

after getting a stock ecu reflashed to DP ecu, i chopped an airbox lid and purchased a KN high performance filter, and installed them both this weekend.  this worked fine saturday and then the first part of sunday.  however coming home on sunday in the evening (temps still in the 90's and humid), in city stoplight driving, it died on me about five or six times (i lost count) in a 10-15 minute period.  temps on the gauge read around 220-225; not sure if this was related.  what would happen would be i would be stopped at a stoplight, and then i start to accelerate from the light in first, and the revs dip down and climb as normal, but right about 3k rpms, there's this "cough" sound i can hear coming from the intake, and it dies.  same each time...somewhere right around 3k.  but for hours before that, i was running around the city and had no issues with dying (though was riding it much more aggressively ).  i took it out again yesterday AM for a quick run for coffee with a friend, and neither there or back had any issues with dying.

it's worth noting though that i noticed this "cough" a long long time ago, even with stock airbox and filter, and stock ecu.  there was this spot at 3k where it would just cough or stumble briefly, and then continue on through the revs (though never died before).  i would notice it a lot in city driving, where i would be making a left or right turn from a light, easy on the throttle...and would hit that stumble.  it's a pretty disconcerting feeling just suddenly losing power.

so, i'm just curios if others have experienced this or heard of it happening?  anyone have an idea of what the cause is?  fuel trim?  i've had the DP-flashed ecu installed now for a couple weeks; it wasn't until the choped lid and new filter that it died.  i'm still trying to figure out how to use a vdst and get it to reliably talk to my ecu so that i can fatten up the fuel trim... so maybe that's all that's causing this?  i got a PASS message on saturday when attempting to reset the TPS, so afaik that part is done.

[♣ McKraut ♣]

and crap..i meant this for the tech section.  if someone wants to move it that's cool

[el_loco]

I've been browsing the Tech section looking for ideas on this same kind of issue.  I've noticed three or four times now on my 2002 750s, I'll be in first, accelerating and about 3k RPM's it'll feel like and electrical short or "cough" and then pick back up and run without a problem after.  At first after this would happen my oil temp readings would then bounce all over.  I tightened the oil temp sensor and thought I had fixed it, but after I fueled up yesterday, as I took off from the red light it happened again.  Though now I don't have the oil temp fluctuations so I am not convinved the two were ever related.  I'll be checking back to see what folks say

[booger]

Have either of you considered the possibility of bad gasoline. I just recovered from a bout with bad fuel, quite similar symptoms. Takes a couple tanks to pass. Also, if the valves need an adjustment it will do that coughing through the airbox at part throttle crap.

[♣ McKraut ♣]

Fuel: I suppose that's possible; I just filled up at a shell by my place that I've used many times before. But would that be suspect when it's at the same rpm every time?

Valves: bike has about 25k miles, and had valves inspected by a very respected ducati tech one year ago (4 or 5k miles ago) he said all looked well and I don't believe he made any adjustments (though I would have to dig out the invoice to make sure)

[booger]

All I'm saying is I'd get that coughing and farting through the airbox(I have the DP ECU/airbox) at 3.5-4.5k rpms and really the only thing that definitively solved it was a valve adjustment. I too had taken my bike to a VERY reputable dealer(as in won the award for being second best on the East Coast even though not anywhere near the coast) in the DC area and was told the valves were checked but when I broke it open it soon became apparent that they weren't. Sometimes you've got to see for yourself. That's why Ducatis are such great bikes. They turn riders into mechanics. I got the valves adjusted myself, and poof no funny stuff thereafter. Your bike is likely struggling to breathe. I'd make sure the valves are opening and closing as they should be and compression is being maintained in both cylinders before I'd go trying to trim up the fuel. Have you even pulled the plugs to note their condition? This could confirm/deny your suspicion that the bike is lean.

Also I might add, that valves having been checked a year ago and observed to be within spec, could now be nicely out of spec, depending upon just how within spec they were observed to be one year ago. Make sense? It's a Ducati. Check them again to be 100%.

[♣ McKraut ♣]

All I'm saying is I'd get that coughing and farting through the airbox(I have the DP ECU/airbox) at 3.5-4.5k rpms and really the only thing that definitively solved it was a valve adjustment. I too had taken my bike to a VERY reputable dealer(as in won the award for being second best on the East Coast even though not anywhere near the coast) in the DC area and was told the valves were checked but when I broke it open it soon became apparent that they weren't. Sometimes you've got to see for yourself. That's why Ducatis are such great bikes. They turn riders into mechanics. I got the valves adjusted myself, and poof no funny stuff thereafter. Your bike is likely struggling to breathe. I'd make sure the valves are opening and closing as they should be and compression is being maintained in both cylinders before I'd go trying to trim up the fuel. Have you even pulled the plugs to note their condition? This could confirm/deny your suspicion that the bike is lean.

Also I might add, that valves having been checked a year ago and observed to be within spec, could now be nicely out of spec, depending upon just how within spec they were observed to be one year ago. Make sense? It's a Ducati. Check them again to be 100%.

the plugs i can check after work.  the valves are another story.  i've never even popped off the valve cover before (is that something i can do without an oil mess on my hands?).  unfortunately i don't even have a garage nor stands (nor do i have valve feeler guides/gauges); though i can probably bug a friend or two to use one of theirs.  all that said, though, i absolutely think he checked them all; he's not known for taking shortcuts.  he's currently just working out of his rather large garage, and has a very loyal following in our local dfw group.  i will get the invoice out later today and i can report what his measurements were for all the valves (though i won't personally know what they mean...well, i know what they mean but i don't know what's good/bad).

[devimau]

it only did it when the engine was really hot and never did it again?
have you had the bike to the same temp without the problem?
in other words, I'm trying to find out if the problem was there since you installed the ecu but because you never reached certain temperature it did do it before.
have you had the tps  reseted and co adjusted after you installed the ecu?

[el_loco]

Sorry to semi thread jack, but I'll take a shot in case I by chance add something not already mentioned.

I don't know about McKraut, but my issue is extremely random and very occasional.  I imagine if the issue is being caused by valves out of spec I'd be able to replicate it.  I almost wonder if it's related to when I fuel up, like maybe I'm over filling the tank and it's causing a sporadic flow issue, or because I have an aftermarket fuel cap (De Pretto Moto) if the system needed to re-establish proper vacuum after it's been opened for fueling up?  My unfamiliarity with the Ducati fuel system leaves me at a disadvantage.

I still maintain that what it felt like on my monster was more of an electric short, like I lost spark for two or three revolutions and then picked back up again.  But I suppose if it were a brief interuption in fuel delivery it would act the same way.

[♣ McKraut ♣]

it only did it when the engine was really hot and never did it again?
have you had the bike to the same temp without the problem?
in other words, I'm trying to find out if the problem was there since you installed the ecu but because you never reached certain temperature it did do it before.
have you had the tps  reseted and co adjusted after you installed the ecu?

temps:  yes, so far it's only done it that once, though i've only ridden a few times since last weekend.  this (sunday PM) was the first time i saw 220's i *think*... but i know i've been close to that before since installing the ecu... like 21x.  i've seen plenty of super hot temps pre-flashed ecu (i live in dallas tx), well into the 220's.
tps reset:  i've tried many times so far with a vdst for a 5AM ecu, and it's been spotty thus far.  i have been able to receive the "PASS" message for TPS reset though, a couple of times.  so, if that's all that's required for TPS reset than i *think* that has happened.
fuel trim: haven't been able to adjust it yet... so far it just looks "greyed out" in the vdst software (engine running).  so fuel mapping/trim is still whatever DP spec is

[errazor]

Maybe it is something simple, like a loose earth bolt on the ecu or the engine block.

[devimau]

Maybe it is something simple, like a loose earth bolt on the ecu or the engine block.

that's a valid point but if the bike does it @ an specific temperature I will suspect on co adjustment.
the hotter it get the leaner it gets and if you only reseted the tps and never checked co % there's a big chance that the bike is not running as balanced as it should be and might be causing the bike to stall due to a lean condition.
I'd balance the co% before I do anything else.

[DucHead]

My bike has been doing this for the past few days -- when its been reeeeeally humid here in Raleigh.

I have the airbox removed and K&N filters fit, with Boom Tubes. 

BTW, my Boom Tubes have been popping like mad on decel recently.

Also, I'm waiting on a local guy to fit a PCIII and dyno tune my bike.

[♣ McKraut ♣]

i will try to get the vdst hooked up again today or tomorrow and see if i can get that fuel trim adjusted.  i haven't had any luck so far.  i may send it back and have them reflash it, just to make sure it truly is flashed to DP spec because thus far everything looks greyed out in the vdst software.  i'll also pull the plugs and see how they're looking and post up the valve measurements as of last year (i know... it's probably not that helpful to look at measurements a year old, but i don't have the ability to take measurements on my own.).

[♣ McKraut ♣]

valves a little over a year ago measured (to be honest i don't even know what the unit of measurement is):

Front
exhaust: 77
intake: 56

exhaust: 66
intake:  66

Rear
exhaust: 66
intake: 66

exhaust: 66
intake: 77