[Fred]

You say you changed the sparkplugs. If you're capable of changing the plugs, you're CERTAINLY capable of syncing the throttle bodies, which is MUCH easier.

 

[abe57]

You say you changed the sparkplugs. If you're capable of changing the plugs, you're CERTAINLY capable of syncing the throttle bodies, which is MUCH easier.

If you have the right tools !! LOL

 

[9Lives]

Your technical explanations were interesting to a number of us in this forum; just hard to reconcile with personal experience. No offense intended.

None taken, just speaking from training and experience. I was on the same train of thought until I was proven wrong. When you apply some of the laws of physics it make perfect sense.

Objects in motion tend to say in motion in a strait line unless acted upon by another force (air is an object, it has mass and weight). In this instance the force that comes into play is difference in air pressure between the two openings in the port.

Vacuum (AKA) low air pressure or more specifically lower that atmospheric air pressure, is created by a resistance to air flow caused by the throttle plate. In basic terms the low air pressure is below the plate and atmospheric pressure above. The other end of the port exits just below the throttle plate in the idle or closed position. When the throttle plate rotates more a few degrees, that port is now above the plate so in theory the pressure is the same on both ends of the port effectively removing the the "other force" that would cause the air to flow through that port. Will absolutely no air pass this port? No, but at this point the tiny amount of air that could possibly pass through would have no measurable consequence to the combustion in the cylinders.

 

[psycoreefer]

To OP.
Was your TPS changed out?
If so and you are still having this issue I would change your APS, assuming you already had/have your ECU flashed which helps smooth everything out.
I had the issue you described for a long time. I tried spark plugs, coil packs, tb sync, diff fuels, new throttle tube, and kevs O2 controller all to no avail. Almost gave up. After seeing some posts on here changed my TPS and APS and problem finally solved!

I believe the cause is one or both (APS & TPS) give out an unstable, call it twitchy, signal which in turn causes your tb butterfly valves to "twitch". The joys of ride by wire 😉

Any chance you've still got the old (bad) sensors? I'd be interested in hooking up an o-scope and seeing if the 'twitchy' signal could be quantified to help others in future diagnostics.

 

[GreatHolio]

What does that have to do with my engine stutter?

BahahahahahahahHHhHahHHahhahahahahHHHHHHHHahahahahahahahahahahHahaha. I have no clue how my reply to another thread entirely, ended up here! Sorry!

 

[GreatHolio]

no longer flow through the port.

This is not true for a fluid! It will still flow through the small port. And it will affect the throttle at any rpm.

Unless you know if some new theory of physics that says fluids will ONLY go through the path of least resistance and ignore other paths.

Look at a small stream, there is always a path of least resistance, but water still does flow through many other paths.

 

[9Lives]

Your water example, plus the air through your nostrils example completely disprove my explanation. Well done

 

[GreatHolio]

Next time I do a throttle body sync, I'll purposefully keep one adjustment high and record the results at low RPM and high RPM.

I'll be using this tool here witch creates a nice graphical view. eSync Tool (EST) - HealTech Electronics Ltd.

 

[9Lives]

Are you going record your findings while riding the bike? The throttle position is going to be much different while riding and maintaining a constant RPM than when there is no load on the bike.

The way this was proven to me was on a dyno. Bike running in 6th at around 110 kmph with the throttle locked. The screws where turned all the way in, then all the way out. Everything flatlined on the dyno, hp, tq, afr’s no effect whatsoever.

 

[Klye07]

Any chance you've still got the old (bad) sensors? I'd be interested in hooking up an o-scope and seeing if the 'twitchy' signal could be quantified to help others in future diagnostics.

I believe I still do, let me check...

 

[Screan29]