Question TRYING to solve the snatchy throttle

[Piggy]

Yes, I have put AIS block off plates bought on the web, and remove all the valves system, without any fault ...
this was part of all the mods but I doubt this one alone has a big effect.

If you change the TPS setting a bit, keep us informed of your feeling ...
thanks

What were the benefits of the blanking plates?? I'd like to make a custom fresh air intake for the airbox and have thought the recirculation system is right in the way

 

[francesco21]

the main bénéfits to take off all this system are to make more place to work on the motor
and also to allow an accurate reading of the air/fuel ratioo when mounting a fuel controller ...
there is many posts on the forum about this subject,
but alone this won't help the snatchy throttle

 

[Tony@west oz]

Its a common thing with the FZ6, and the harder you work on smooth roll on throttle with fast track riding at high rpm, the more obvious it becomes.
Some say they don't experience it but I believe its almost 100% of all FZ6s.

I am glad to find so much info on it on this forum, as after posting on a UK Facebook group, some told me it was my riding. I worked tirelessly to improve my inputs... but finally took to recoridng my throttle movement v bike response and it was so obvious it had this dead spot. Which when you're really on it on track, higher rpm, crack the throttle mid turn, its violent sometimes and instructors have a go at me for being too brutal with the throttle!

Anyway, my bike is a 2008 FZ6s. I love the thing. But if I cant solve the throttle issue, or seriously improve it, I have to look for a different bike, I've ridden other modern FI bikes and they are smooth.

What I have done so far;
Checked and adjusted throttle cable, perfect.
Checked the TPS via onboard diagnostic mode, goes from 0% to 1% perfectly, as soon as the throttle moves. No jumping.
Balanced the throttle bodies.
Fitted free flowing exhaust and decat.
Adjusted C02 levels via on board diagnostic mode.
Ignition advance cog/wheel.
(bike is fully serviced and up to date, always use 97/99 fuel, valve clearances spot on)

None of the above have made any difference to the throttle snatchy/jerk from 0% to 10% as you roll on. Very very very very notcieable in 2nd and 3rd at mid/high rpm. Less so at the same speed but in 5th or 6th. . . naturally.

I have heard Power Commanders can help.. but its more money I could put towards a different bike, which I don't want to do, but I have to spend wisely at this stage. (especially as the other weakness, the front end suspension, would warrant some money)

HELP!
Piggy

Hey Mate , I have a 2009 FZ6n , regarding the snatchy throttle ,Mine was the same so I bought a Power Booster for it online . The difference now I get smooth gear changes all through the rev range . Not a Power Commander .easy fit in the air filter box ,I think they were from Sweden or somewhere like that . Had mine for 3 years and best thing I ever bought for it also K&N Air Filter . Cant remember off hand on Price but Google it and You will find the info . Im in Australia . Hope this helps

 

[Piggy]

Hey Mate , I have a 2009 FZ6n , regarding the snatchy throttle ,Mine was the same so I bought a Power Booster for it online . The difference now I get smooth gear changes all through the rev range . Not a Power Commander .easy fit in the air filter box ,I think they were from Sweden or somewhere like that . Had mine for 3 years and best thing I ever bought for it also K&N Air Filter . Cant remember off hand on Price but Google it and You will find the info . Im in Australia . Hope this helps

Ok, many thanks. I'll look it up

 

[Piggy]

Hello Piggy,

I am the owner of a 2007 FAZER S2 and I agree with you :
the fazzy is a very well built bike, with many abilities and qualities … we are all aware that,
but the snatchy throttles (and also sometimes the gearbox) is a major defect, which can be very annoying.

If you look at others bikes of the same technology, same years, I think about an HONDA CB 600 FA or a SUZUKI GSXF 650 for examples,
they are smoother and much more pleasant to drive for a quiet ride.

For sure, some drivers get used to it or accomodate this ; but ride another bike and this Fazzy defect become obvious.

So the question is : How is it possible to reduce it … ?

As you, I have tried a lot of things :
- advance timing something betwenn +3,5 and +4 degrees
- decat tube
- remove the two small cats in the header and welding
- remove AIS plates
- perfect setting of throttle cable, throttle bodies ...
- CO1=+10 and CO2=+10 (origin was 0 and 0)

I must said this help, but not enough to my taste.

So I have tried another mod, which give good results : I change the TPS setting :
My OEM setting was 16-101 at the dashboard : I move it a bit, in order it was 18-103.
here is a link to a vidéo :

this change the fuel timing for a given opening throttle.
It also change the ignition timing and I would like to see the maps for all gears (not sure the +4 degrees ignition advance is a good thing with this TPS setting...).

But despite this, this is a good way to test to improve the snatchy throttle.

working on a video...

I was super optimistic I have to admit but after an hour of making this adjustment... It made absolutely zero difference to the snatchy throttle I am experiencing sadly.

 

[Piggy]

The throttle plates at idle should be just off from a full block.

Can I just confirm what you have in mind/mean here? "just off" could mean a lot of things depending on the person... should I be able to see the gap? Measure only with feeler gauges?

 

[Piggy]

Hey Mate , I have a 2009 FZ6n , regarding the snatchy throttle ,Mine was the same so I bought a Power Booster for it online . The difference now I get smooth gear changes all through the rev range . Not a Power Commander .easy fit in the air filter box ,I think they were from Sweden or somewhere like that . Had mine for 3 years and best thing I ever bought for it also K&N Air Filter . Cant remember off hand on Price but Google it and You will find the info . Im in Australia . Hope this helps

IS this what you used?

 

[Tony@west oz]

Ok, many thanks. I'll look it up

Its called booster plug and its from Denmark , $169 USDollars

IS this what you used?

 

[Tony@west oz]

Its called booster plug and its from Denmark , $169 USDollars

 

[Tony@west oz]

Its called booster plug and its from Denmark , $169 USDollars

Yes

 

[Piggy]

Its called booster plug and its from Denmark , $169 USDollars

Ok, so tried this.
Fitted as per manual etc

Makes absolutely no difference to how the bike runs imo. Rode before. Plugged it in. Rode same ride, same day. Nothing changed that I could discern to throttle.

What I did note;

It obviously changes the IAT, about 18-20° less than normal, which would change fueling SLIGHTLY... But I don't like it that the engine is seeing the wrong figures... It also made the engine run a bit hotter than normal, not much, but noticeable.

I'll be sending the box back.

And... Back to the drawing board for ideas.


First post in the thread has a video of the issue by the way

 

[Gary in NJ]

Have you checked the fuel pressure? It seems like you’ve checked everything but fuel delivery.

 

[Piggy]

Have you checked the fuel pressure? It seems like you’ve checked everything but fuel delivery.

Hey Gary, thats a fair shout, I have not... but I have no evidence to suggest it was fuel delivery pressure related...

as at full throttle and high rpm, theres no lack or drop in power at all. Or full throttle from low down throttle, full load, it doesnt struggle through a pull to high rpm.

However, how would I check fuel pressure? I have not seen any figures or ways to check and I don't think there is a fuel pressure sensor on the rail?

 

[Gary in NJ]

Just for descriptive background, here is a excerpt from the FSM:

The fuel pump delivers fuel to the injector via the fuel filter. The pressure regulator maintains the fuel
pressure that is applied to the injector at only 250 kPa (2.5 kg/cm2). Accordingly, when the energizing
signal from the ECU energizes the injector, the fuel passage opens, causing the fuel to be injected into
the intake manifold only during the time the passage remains open. Therefore, the longer the length of
time the injector is energized (injection duration), the greater the volume of fuel that is supplied. Conversely,
the shorter the length of time the injector is energized (injection duration), the lesser the volume
of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals that are input from the
throttle position sensor, crankshaft position sensor, intake air pressure sensor, intake temperature
sensor and coolant temperature sensor enable the ECU to determine the injection duration. The injection
timing is determined through the signals from the crankshaft position sensor. As a result, the volume
of fuel that is required by the engine can be supplied at all times in accordance with the driving
conditions.

The in-tank fuel pressure assembly includes (1) the fuel pump, (2) the pressure regulator, and (3) the fuel filter/screen. This self contained system feeds the fuel rail and injectors. Since this is self-contained, you can simply hook-up a pressure gauge to check that the system makes and maintains 250 kPa. The fuel system has two components, the aforementioned fuel delivery system, and the fuel management system. The fuel management system is comprised of the ECU and it's associated sensors; TPS, IAT, IAP, ECT and CPS. Since you have largely diagnosed this system, it is time to review the fuel delivery system. Sometimes diagnostics is a process of elimination...but the fuel pump assembly is a known weak area for the FZ6 with unpredictable performance characteristics when in a failure mode.

 

[Motogiro]

Because I've heard so much about snatchy throttle and I've had the FZ6 dyno'd I learned that there was a function in the fuel management (Power Commander III USB) that over rides the FZ6 fuel injection lag. That lag may have been part of the stricter emmission standards that manufactures needed to meet. There is a function on the power commander III USB that acted as a primer pump with carburetors. Actually they called it accelerator pump. This function was available with the Power Commaner III USB. Likely this changed the fuel injector pulse width the instant there was a positive TPS value. With fuel injection you could get a leaner response than a carburetor and this could help pass emmissions. With spirited riding in a turn where you're keeping RPM in the power band you want, this will become a problem. Even though you should be maintaining throttle there are conditions where you unload and then load the rear wheel. As you become more familiar with riding the snatchy throttle will become less of a problem but it is still a problem at any skill level of riding.
More info: https://www.dynojet.com/amfile/file/download/file/56/product/3887/
I agree with Gary that there have probably been damages to bikes either from defective fuel management devices or ill programmed devices. TBH I've heard more crap shoot tuning of CO and fuel management devices than actual reputable tuning.
If you're going to use the PC III USB, start with a zero map and access the accelerator pump feature and see if you can get some joy killing the throttle latency.

 

[Piggy]

Just for descriptive background, here is a excerpt from the FSM:

The fuel pump delivers fuel to the injector via the fuel filter. The pressure regulator maintains the fuel
pressure that is applied to the injector at only 250 kPa (2.5 kg/cm2). Accordingly, when the energizing
signal from the ECU energizes the injector, the fuel passage opens, causing the fuel to be injected into
the intake manifold only during the time the passage remains open. Therefore, the longer the length of
time the injector is energized (injection duration), the greater the volume of fuel that is supplied. Conversely,
the shorter the length of time the injector is energized (injection duration), the lesser the volume
of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals that are input from the
throttle position sensor, crankshaft position sensor, intake air pressure sensor, intake temperature
sensor and coolant temperature sensor enable the ECU to determine the injection duration. The injection
timing is determined through the signals from the crankshaft position sensor. As a result, the volume
of fuel that is required by the engine can be supplied at all times in accordance with the driving
conditions.

The in-tank fuel pressure assembly includes (1) the fuel pump, (2) the pressure regulator, and (3) the fuel filter/screen. This self contained system feeds the fuel rail and injectors. Since this is self-contained, you can simply hook-up a pressure gauge to check that the system makes and maintains 250 kPa. The fuel system has two components, the aforementioned fuel delivery system, and the fuel management system. The fuel management system is comprised of the ECU and it's associated sensors; TPS, IAT, IAP, ECT and CPS. Since you have largely diagnosed this system, it is time to review the fuel delivery system. Sometimes diagnostics is a process of elimination...but the fuel pump assembly is a known weak area for the FZ6 with unpredictable performance characteristics when in a failure mode.

Totally familiar but that was a great breakdown and maybe useful for anyone in future finding this thread. Very nice, thanks.


Just surprised having full rail pressure at full throttle, shutting throttle, then opening again at lower rpm, there would be pressure ready. . . But I'll take a gander... Wonder if it turns the fuel pump off at that moment??

 

[Gary in NJ]

I got out this morning on my FZ6 for a ride, and I decided to try and recreate the throttle-lag test that is shown in the video in post #1. I couldn't make the FI system misbehave. The problem you are experiencing is completely opposite from how my bike reacts to open/close/open throttle applications at high (and low) rpm. I have instant response from less than a single degree of throttle application.

 

[Piggy]

I got out this morning on my FZ6 for a ride, and I decided to try and recreate the throttle-lag test that is shown in the video in post #1. I couldn't make the FI system misbehave. The problem you are experiencing is completely opposite from how my bike reacts to open/close/open throttle applications at high (and low) rpm. I have instant response from less than a single degree of throttle application.

Thanks for trying that

I'm aware that it's a bit of a 50/50 thing, I've heard many ride stock and modded FZ6s without this issue and keep saying it's in my head or my controls aren't smooth enough...

But about 50% of replies are either, yes I'm trying to sort it too, or 'oh, glad to hear someone else experiencing that' ...

I just wish I could sort it to ride like yours

 

[skelly]

If I am right, I think that when you close the throttle, the fuel is not delivered to the common fuel rail and that a vacuum line opens the fuel pressure regulator to return unwanted fuel to the tank, if there is a leak at any point in your vacuum lines it can cause lag and snatch, lag because the fuel isn't there when it should be, then snatch because it arrives as everything is telling the engine to rev higher. I would very carefully check the vacuum lines, a PITA to do but well worth it as it could be the problem and won't cost much to fix.
Good Luck.

 

[Piggy]

If I am right, I think that when you close the throttle, the fuel is not delivered to the common fuel rail and that a vacuum line opens the fuel pressure regulator to return unwanted fuel to the tank, if there is a leak at any point in your vacuum lines it can cause lag and snatch, lag because the fuel isn't there when it should be, then snatch because it arrives as everything is telling the engine to rev higher. I would very carefully check the vacuum lines, a PITA to do but well worth it as it could be the problem and won't cost much to fix.
Good Luck.

While I do like this thinking...

I thought the regulator was in the tank?

And even if there was a delay in this .. the rail would still have fuel pressure so as soon as the injectors opened, there would be fuel delivered... Then a drop in pressure while it lagged behind building again... Then build up

?