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3000rpm hiccup


Lucky Phil
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On 9/15/2021 at 12:55 PM, Lucky Phil said:

I just had a thought triggered by an issue on the V85TT's caused by what appears to be EMI from the ignition coil affecting the crank angle sensor pickup cable. Causes erratic idle apparently and the Guzzi TSB fix is to re route the wire away from the HT lead I'm led to believe.

I was wondering if anybody with the 3000 rpm hiccup as a chronic issue on their bike might like to see if the crank angle sensor pickup cable or connector is anywhere near the HT lead to the sparkplug. Looking at old images of the wiring on my bike before the engine swap the connector and cable were right next to and touching the r/h coil HT lead. Might be worth looking at and if it's close reroute the cable to keep it as far away as possible and see if there is an effect. ( the std cable has lots of length from memory) 

 

Ciao

My bike had a 3000 rpm hiccup, which went away after I fitted new rubbers between the throttle bodies and the heads (mentioned by Jaap), and set the valve clearance wider than spec.

But EMI interference is an interesting thought. You can reduce this by avoiding any parallel runs of cables next to the leads, or increasing the gap between the cables and leads. Double the gap, quarter the EMI.

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At this point, I can probably list at least nine different hiccup sources afflicting our V11.

If I were the soundman, and this were the audio feed, I would be smoothing these corners out. Jus' sayin' . . .

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I looked at the ignition map from the .bin file Meinolf posted here about 4 years ago and the ignition numbers around the area we are talking about are nothing like the std map FWIW. Caveat to this though, when I looked at the main fuel map it looked a bit weird so I dont know what the issue is there, maybe my IT skills. The ignition map looked normal but very different to std. He also uses different throttle and rpm load points as well. Maybe he'll be along to explain at some point.

Ciao 

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Could the infamous 3000 rpm hiccup be geographically driven?

Why no issue at greater throttle openings?

There isn't an hygrometer sensor part of the circuit, correct?

Say you are living somewhere with high temperatures, and high humidity; therefore your mixture has more water vapor for the given volume, less room for oxygen. So you would need more fuel to obtain the same combustion efficiency.

If the ECU mapping does not allow for more fuel to compensate for the poorer oxygen mixture, then you get the cough?

This would explain why I don't seem to see the problem when the air is cooler, even if the humidity is the same.

Water vapor, or the dew point is inferior, so less water vapor means more oxygen, better combustion?

Do people living in cold places have that 3000 rpm hiccup?

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Those are all valid observations. No doubt, the V11 loves cool, dense, dry air to combust. Water vapor displaces oxygen and is not flammable.

Also, this tendency to cough, or hiccup, in this range is decidedly multicausal. Again, I could list a dozen contributors.

That the cam profiles and valve/port sizes are not conducive to this business of dragging around below 4000 rpm is by design as no one has ever complained that their V11 coughs while ripping from 5000 rpm to redline.

Here again, "You can ask your tango chick to waltz. She'll do it, but it pisses her off." B)

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5 hours ago, p6x said:

Could the infamous 3000 rpm hiccup be geographically driven?

Why no issue at greater throttle openings?

There isn't an hygrometer sensor part of the circuit, correct?

Say you are living somewhere with high temperatures, and high humidity; therefore your mixture has more water vapor for the given volume, less room for oxygen. So you would need more fuel to obtain the same combustion efficiency.

If the ECU mapping does not allow for more fuel to compensate for the poorer oxygen mixture, then you get the cough?

This would explain why I don't seem to see the problem when the air is cooler, even if the humidity is the same.

Water vapor, or the dew point is inferior, so less water vapor means more oxygen, better combustion?

Do people living in cold places have that 3000 rpm hiccup?

Yes docc is right and as I pointed out earlier the V11 and every other ICE engine has areas in their operating envelope that are less than ideal to support perfect combustion. That's why modern engines have Variable inlet and exhaust cam timing, variable length intake runners, exhaust valves,knock sensors  and much more sophisticated ecu's and monitoring of the combustion process. It's all driven by the need to maintain/improve output and reduce emissions. 

The local atmospheric conditions play their part of course but I f the engine wasn't so touchy around this area it wouldn't matter as much as it does. Years ago I was tuning my Triumph Speed Triple for a race 3 into 1 exhaust and the problem I was having was idle and carburation just off idle. In some weather conditions it was perfect and on other days it was an  issue. There is a "box" mixture wise in this case that the engine will operate in happily but if the carb settings were on an average day right at the edge of that "box" then any relatively small variation in atmospheric conditions would take you out of the "box" and the engine wouldn't carburate nicely. The aim was to jet in the middle of the "box" on an average day so when you have the atmospheric variations either way the mixture stays "in the box". In the case of the V11 "maybe" the "box" around this 2700-3000 rpm area is very small due to the design of the engine and it's hard to get it in the "box" and keep it there due to all the variables. looking at the Meinolf and std ignition mapping I was just wondering whether it was the ignition map that was the critical issue as the std map seems a bit strange in that area.

In the absence of Meinolf responding is anyone running his map and can contribute to the Hiccup propensity?

Ciao     

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5 hours ago, docc said:

Here again, "You can ask your tango chick to waltz. She'll do it, but it pisses her off." B)

I lived in Argentina from 2003 until 2008....

Tango is not something easy to master; besides you can only Tango properly with someone who knows how to dance it well not withstanding that person and you need to have danced it together...

On the other hand, you can Waltz with just anybody as long as you understand 3/4.

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@Lucky Phil

Back in my racing days, we used to do what was then called a carburetion's imaging:  but that was with two strokes engine...

We would do one run at full charge, shut down the engine and determine the jetting based on the spark plug coloration. A very crude way of getting the best fueling based on the local atmospheric conditions.

I am guessing the 3000 rpm V11 stutter is there to stay then...

 

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3 hours ago, p6x said:

@Lucky Phil

Back in my racing days, we used to do what was then called a carburetion's imaging:  but that was with two strokes engine...

We would do one run at full charge, shut down the engine and determine the jetting based on the spark plug coloration. A very crude way of getting the best fueling based on the local atmospheric conditions.

I am guessing the 3000 rpm V11 stutter is there to stay then...

 

Yes we called it a plug chop. Not really possible on a road bike in road conditions. Not sure about the stutter staying someone needs to play with the ignition mapping and find out if thats the issue or failing that the fuel.

Ciao

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The full "decent tune-up" is an excellent place to start. The TPS and CO are important, but so is synching the throttle bodies. Can make a huge difference. Just before synching, give that white knob a full turn and watch how she runs. If you are replacing intake rubbers and cannot therm to separate from the head, try that and they should "pop" right off.

The early XS650 Yamahas had totally separate CV Mikuni 38s. Synching them was an exercise in futility. I finally installed a balance tube from diaphragm to diaphragm and while that helped, the cure was linked carbs, which Yamaha came up with as part of their emissions work on the ancient air-cooled two valve engine. 

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On 9/18/2021 at 6:08 AM, Lucky Phil said:

I looked at the ignition map from the .bin file Meinolf posted here about 4 years ago and the ignition numbers around the area we are talking about are nothing like the std map FWIW. Caveat to this though, when I looked at the main fuel map it looked a bit weird so I dont know what the issue is there, maybe my IT skills. The ignition map looked normal but very different to std. He also uses different throttle and rpm load points as well. Maybe he'll be along to explain at some point.

Ciao 

Hi,

maybe this will clarify some of the questions. AFR/Lambda and ignition timing are closely intertwined. The flame through speed of the mixture varies with Lambda, up to -20%.

The fuel values in my V11 BIN are based on a Lambda target map, which is based, amongst other considerations, on MAP at the respective breakpoints. I use a meager mixture at low MAP breakpoints and richer mixture in areas with less throttling loss.

Hence the fuel values vary a lot from one breakpoint to neighboring ones if this is where the target lamba changes from 1.0 to 0.94 (as example). This variation is most pronounced when moving from the fuel shut-off area (better engine breaking) to the fuel-injected areas.

The ignition values reflect the mixture. Meager mixture = earlier ignition, richer mixture = later ignition.

The earliest ignition values are used in the fuel shut-off area to minimize popping in the exhaust, which is caused by a lean mixture not igniting in time.

As to the thread topic - the hiccup. If no other faults, most of them were already mentioned in this thread, are present, hicc-ups in my experience are always the result of a lean mixture. The V11 engine runs reasonably well with Lambda 1, but deteriorates quickly if the mixture gets leaner.

Cheers
Meinolf

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12 hours ago, Meinolf said:

  

Hi,

maybe this will clarify some of the questions. AFR/Lambda and ignition timing are closely intertwined. The flame through speed of the mixture varies with Lambda, up to -20%.

The fuel values in my V11 BIN are based on a Lambda target map, which is based, amongst other considerations, on MAP at the respective breakpoints. I use a meager mixture at low MAP breakpoints and richer mixture in areas with less throttling loss.

Hence the fuel values vary a lot from one breakpoint to neighboring ones if this is where the target lamba changes from 1.0 to 0.94 (as example). This variation is most pronounced when moving from the fuel shut-off area (better engine breaking) to the fuel-injected areas.

The ignition values reflect the mixture. Meager mixture = earlier ignition, richer mixture = later ignition.

The earliest ignition values are used in the fuel shut-off area to minimize popping in the exhaust, which is caused by a lean mixture not igniting in time.

As to the thread topic - the hiccup. If no other faults, most of them were already mentioned in this thread, are present, hicc-ups in my experience are always the result of a lean mixture. The V11 engine runs reasonably well with Lambda 1, but deteriorates quickly if the mixture gets leaner.

Cheers
Meinolf

Ok Meinolf thanks for the explanation, I understand the fuel map now. It just had some large values where I didn't expect to see them and thought I might have done something wrong with regards to the download and input into Tunerpro.

docc why dont you give this map a try and see if it eliminates the hiccup. It's very different to the std map but in a safe way/direction as you would expect from Meinolf. Std maps for some reason on multiple brands are shall we say less than optimal. Probably because they are trying to cover every possible scenario in every part of the world. It's a rare event to have a std really good map I think, not impossible but over the years I've had factory updates from quite a few manufacturers multiple times trying to eliminate running issues. 

Ciao  

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Yah, so, I don't often force my Sport to ride at those low RPM / low throttle angles. It really does piss her off, especially if the ambient temps and humidity are high. But it happens on rare occasion. And she hates it!

 

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On 9/20/2021 at 3:42 AM, docc said:

Unfortunately,  Meinolf's map also specifies closed air bypass screws and very loose valve tolerances that I cannot accept. Perhaps his map is ideal for the atmospheric conditions and available fuels in his locale. I have to deal with my local conditions: sorry-corn-fed fuel and hot-humid air that is remiss to combust.

Hi,

the explanations here https://www.v11lemans.com/forums/index.php?/topic/23210-tps-reset/&do=findComment&comment=265226 may shed some light on the valve play/bypass screw topic.

The atmospheric conditions (baro pressure/ambient temperature) are taken care of by trim tables. I can't comment on the fuel quality, though. But, if it did then any combustion engine in your area would need a adaption, wouldn't they?

Cheers
Meinolf

 

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I apologize for my misunderstanding about the valve clearances and removed that statement from my post.

Thank you, again, Meinolf for your patience and kind explanations! 

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