Author Topic: ECU Fuel and ignition calculation differences Gen1 through Gen3  (Read 343 times)

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Offline Ivan_ipp

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ECU Fuel and ignition calculation differences Gen1 through Gen3
« on: January 20, 2018, 01:17:12 pm »
This is an informational post for reference only

Fuel and ignition calculation differences between the different generations of the C14

Gen 1 – 2008 - 2009
Gen 2 – 2010 – 2014
Gen 3 – 2015 – 2018


Fuel calculation multiplier

Gen 1 & 2 use the same multiplier.
Gen 3 uses a smaller multiplier for fuel calculations –
This means that the values in each cell from all fuel tables will be a leaner final fuel calculation.

Basic AFR tables

These tables are not the main fuel tables... they are offset trims that will skew the final fueling calculation from the main fuel tables.

Gen 1 has neutral or no influence changes to it’s basic AFR tables
They are functional, but are set to a “neutral” value.

Gen 2 & 3 have major changes to their basic AFR tables below 5000 rpm

This makes it obvious that the same fuel tables should not be used across all 3 generations without changing both the basic AFR tables, and the fuel calculation multiplier to be the same in all the files.

Not doing so will result in rich or lean depending on which generation C14 was used to make the fuel changes.

Knowing this, allows me to give consistent results on all three generations of this bike.

Injector Timing

This is the timing of when the injectors will spray their fuel in relation to piston position and cam timing.

This is a fairly complicated area, but suffice to say that the C14 injector timing is set from the factory to give the lowest emissions period..... adjusting this on the dyno, before adjusting the final fueling has resulted in a very nice improvement in power and driveability at all throttle positions across the entire rpm range.

Warm up corrections

The 3rd generation of this bike ends it’s warm up cycle sooner than the first 2 generations because its possible during cold weather that the bike will get below the temp that would cause it to re-enter warm-up fueling. I have included these changes in my Gen1 and Gen2 flashes to include these changes.

Gear dependent timing maps

All 3 generations of C14 have gear dependent ignition values. Some of these tables pull 20 degrees of advance at throttle openings of less than 25% in the first 4 gears. This results in excessive heat/response issues, and contributes to jerky throttle behavior.
The 2nd generation being the worst in this regard.
The 3rd gen strategy went back to the first gen gear dependent timing values and reduced emissions differently through leaner fueling, the enabling of the O2 sensor, and modifications to injector timing.

All generations have 5 degrees removed in top gear at less than 25% throttle... this causes less than optimal throttle response and requires more throttle opening to climb a hill or just maintain speed and gives the feeling that the bike weighs 700 lbs.

All generations have an ignition retard sub-routine that affects driveability in addition to the gear dependent maps.
Timing retard used in this manner raises exhaust temps to help keep the catalyst hot... this is it’s sole purpose. When these “features” are turned off, the bikes performance improves quite a bit compared to leaving them intact.

Without reverse engineering all the ECUs for this bike, it would be very difficult to understand all the changes that were made, and to be able to make informed, educated tuning decisions along the way.
I believe that this method gives the very best possible result for everyone.


These are the same across all 3 generations of the C14

The C14 throttle bodies have 2 sets of throttle plates.... One set is controlled by you the rider and is closer to the cylinder head... The other set is above the main throttle plates and are controlled by the ECU and they are used to control the actual airflow independently of what the rider asks for. 

Example If the C14 rider wants to pass a car in 3rd gear, he grabs 50% of the throttle at 3000 rpm, with stock programming, the ECU will allow appx 18% throttle opening. This limits the power that the engine will deliver... (It also will lower emissions from excessive amounts of fueling from sudden acceleration). But, this also limits the power and fun factor that you can have from your 1400cc Grand Tourer.

Finding the best sub-throttle setting for all throttle positions is a pretty time consuming task and is best done on a dyno because small incremental power differences are easily measured. You want the sensitivity of having them completely open, yet not ruin the fuel mileage, and also not have the engine hold back from too much air at low rpms if you just set them to follow the main throttle plates.
I feel that the best setting will allow you to feel like they aren’t there, but will actually aid in maximum power at large throttle openings at lower rpms without ruining the fuel mileage.... kind of like an old CV (vacuum piston) carburetor that has one of my jet kits in it with the vacuum piston opening rate optimized... The best of both worlds.

The C14 also has sub-throttle response delays that are gear dependent... in other words the reaction time it takes for the sub-throttle shaft to reach it’s target is not immediate in the lower gears. This dulls throttle response and reaction. This is addressed in my programming.

Variable valve timing

The C14’s VVT system is programmed from the factory to have little effect below 40% throttle, above this throttle opening, the system will start advancing the intake cam the more you open the throttle, the more it advances... If you are a gentle rider and don’t give much throttle, the VVT doesn’t do much for you.

It also never lets the intake cam fully retard at high rpm. This prevents the engine from producing full power. In order to have the full benefit from the VVT system, the C14 needs to have the system reprogrammed.

O2 sensor function

All 3 generations of this bike have O2 sensor function in their ECUs. North American models have not used this function until 2015 (Gen 3)
There are 4 functions of the O2 sensor that the ECU looks at.. 
I will not describe these here other than to note that turning off the O2’s error code is not the same thing as turning off it’s function.

Once I adjust this and the other items mentioned above are optimized, the results are nothing short of amazing.

Thanks for reading,  :beerchug: