Fuel Cut / Throttle Snatch: Why?

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shelkgoo

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I'm sure many of you are familiar with the fuel cut these bikes have over a certain speed.
I've seen the various ways to fix it including the ECU methods, but I have to wonder:

Why was the bike designed like this in the first place? What was the intention by the engineers or is this a straight up oversight?
Increase mpg? Increase engine breaking?
 
Are you referring to fuel cut on decel? Usually they do it for emmissions reasons, and MPG. Also thats why they have the AIS systems in place, to inject clean air to further reduce emissions while off throttle.
 
Im not adding my maps but please have a read about how these ecu's work on fz1

The problem with this bike, is the ECU Maps used by Denso.
It's unlike any normal tuning strategy they use.
From factory the bike uses Air Density to control the closed loop 2% to 18% throttle position in the form of the IMAP(intake mass air pressure sensor) and the o2 sensor.(This is where our throttle snatch issue is)
Even if you disconnect the o2 sensor and run a o2 eliminator, the ECU will still be using the IMAP to control 2% to 18% throttle.
Under different load conditions at these throttle openings the bike adjusts it fuel and spark maps accordingly via IMAP
You cannot get around this. Even if you use a PowerCommander, the ECU will always fight the PowerCommander in the closed loop 2% to 18% throttle.
If and when you have your ECU flashed, the tuner needs to get rid of the closed loop 2% to 18% and change to open loop.
Another very important step is, the tuner needs to change is the ECU strategy to Speed density (remember they are from facory air density)..
This way they ECU determines what needs to be done via TPS position and RPM
This is what the PowerCommander uses .



I've spent many dollars and many lost hours trying to fix the throttle snatch once and for all.
I tried various tuners who promised me a fix with their flash tune.
After spending close to $3000.00 Aussie dollars on time wasters and dyno's, I was ready to trade her in on something different.

But I couldn't let her go. This was her only fault.
I was told to speak to a Tuner in Western Australia.It was my last chance and you wouldn't believe it, he sorted it out and explained to me the above issue.

I now have no more throttle snatch but need to watch how quickly I turn the throttle as she will spin the rear tyre or lift the front without hesitation.

I actually enjoy riding her now.
I never really did before because of the throttle snatch.

And another upside of all this is that my fuel economy is now on average5.1 to 5.7 l/100km.
 
falcon_6 said:
Im not adding my maps but please have a read about how these ecu's work on fz1

The problem with this bike, is the ECU Maps used by Denso.
It's unlike any normal tuning strategy they use.
From factory the bike uses Air Density to control the closed loop 2% to 18% throttle position in the form of the IMAP(intake mass air pressure sensor) and the o2 sensor.(This is where our throttle snatch issue is)
Even if you disconnect the o2 sensor and run a o2 eliminator, the ECU will still be using the IMAP to control 2% to 18% throttle.
Under different load conditions at these throttle openings the bike adjusts it fuel and spark maps accordingly via IMAP
You cannot get around this. Even if you use a PowerCommander, the ECU will always fight the PowerCommander in the closed loop 2% to 18% throttle.
If and when you have your ECU flashed, the tuner needs to get rid of the closed loop 2% to 18% and change to open loop.
Another very important step is, the tuner needs to change is the ECU strategy to Speed density (remember they are from facory air density)..
This way they ECU determines what needs to be done via TPS position and RPM
This is what the PowerCommander uses .



I've spent many dollars and many lost hours trying to fix the throttle snatch once and for all.
I tried various tuners who promised me a fix with their flash tune.
After spending close to $3000.00 Aussie dollars on time wasters and dyno's, I was ready to trade her in on something different.

But I couldn't let her go. This was her only fault.
I was told to speak to a Tuner in Western Australia.It was my last chance and you wouldn't believe it, he sorted it out and explained to me the above issue.

I now have no more throttle snatch but need to watch how quickly I turn the throttle as she will spin the rear tyre or lift the front without hesitation.

I actually enjoy riding her now.
I never really did before because of the throttle snatch.

And another upside of all this is that my fuel economy is now on average5.1 to 5.7 l/100km.
Click to expand...

The IMAP (AKA speed density) method needs a MAP (Manifold Absolute Pressure) sensor to work . This bike does not have one, or a intake manifold for that matter. Not sure what this "tuner" is talking about.

MAP- and MAF-Based Air/Fuel Flow Calculator (lightner.net)
 
Last edited:
9Lives said:
The IMAP (AKA speed density) method needs a MAP (Manifold Absolute Pressure) sensor to work . This bike does not have one, or a intake manifold for that matter. Not sure what this "tuner" is talking about.

MAP- and MAF-Based Air/Fuel Flow Calculator (lightner.net)
Click to expand...
The injected bikes uses Air density maps(intake mass air pressure and 02 sensor ) for mapping from factory, so I'm not sure where your headed with this.
Believe it or not but no 17 part on intake parts diagram lists exactly what I've said.
Have a good look at how it all connects to throttle bodies
Even turning off 02 sensor you'll have issues.
This is why you changing mapping to speed density
.654909.png654909.png
 
Disabling 1/2 of the ECU's function and it's ability to compensate for load and altitude is not the correct way to tune this bike, or any bike.

The ECU absolutely needs the MAP sensor to function correctly.
ECU compares the map sensor and baro sensor to calculate elevation and tilt it's fueling corrections for air density.... disabling the map sensor destroys the ECU's ability to do it's job properly. The Map sensor is a vital part of the ECU's function.

Understanding how it works, and what settings to change is how it's done correctly.
Running in AlphaN (throttle position/rpm based fueling) alone is not correct.

There's nothing wrong with the Speed density (vacuum based fueling) in this ecu... it's stock strategy is a bit different from other bikes, but Yamaha wanted this bike to be restricted and fit their vision of how they want it to deliver it's power.... this strategy was part of the way that it was done.

Once we found out how it works, we developed all new software for it, and I spent the last year and a half working on it.
Disabling the O2 is necessary to prevent excessive leanness (14.7-1 is too lean... even for decel on this engine)
If you don't have the proper definitions in your software to disable the O2, then there will be problems with doing this.
This is why I have my own software, and why my products end up with a better result (in my opinion)

There are way more vital parts to tuning adjustments than you get with purchased software.

The end result exceeded my expectations for the FZ1.



Ivan
 
Ivan_IPP said:
Disabling 1/2 of the ECU's function and it's ability to compensate for load and altitude is not the correct way to tune this bike, or any bike.

The ECU absolutely needs the MAP sensor to function correctly.
ECU compares the map sensor and baro sensor to calculate elevation and tilt it's fueling corrections for air density.... disabling the map sensor destroys the ECU's ability to do it's job properly. The Map sensor is a vital part of the ECU's function.

Understanding how it works, and what settings to change is how it's done correctly.
Running in AlphaN (throttle position/rpm based fueling) alone is not correct.

There's nothing wrong with the Speed density (vacuum based fueling) in this ecu... it's stock strategy is a bit different from other bikes, but Yamaha wanted this bike to be restricted and fit their vision of how they want it to deliver it's power.... this strategy was part of the way that it was done.

Once we found out how it works, we developed all new software for it, and I spent the last year and a half working on it.
Disabling the O2 is necessary to prevent excessive leanness (14.7-1 is too lean... even for decel on this engine)
If you don't have the proper definitions in your software to disable the O2, then there will be problems with doing this.
This is why I have my own software, and why my products end up with a better result (in my opinion)

There are way more vital parts to tuning adjustments than you get with purchased software.

The end result exceeded my expectations for the FZ1.



Ivan
Click to expand...
ivan
My bike has never been better than this. Fuel economy, performance and every aspect.
30,ooo plus aussie kms and happy. Prior to this I was gonna get rid of her.
3 other fellow riders on FZ1Ns have also had these issues finally sorted
Power commander is also used to clean up the fuel.
 
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