He has made the info public to aid in development and is not trying to sell anything.
Here are some of his findings.
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Some of you guys may be interested in about the findings of reading the hayabusa ECU program and bench testing of Busa K5/K6 ECU...
First of all the busa ecu is from factory a map select switch ready, even though there is no difference between the maps loaded in the ECU memory. You can start using the second set of maps by grounding the pin 21 on the harness connector - no magic, just a simple switch.
Inside the ECU there is an ignition map for 1st, 2nd 3&4 and 5&6 gears. This enables setting a different advance for 1st and second gear for better 60ft times ... the map is split between two banks, inner and outer cylinders. For neutral/clutch there is just a simple RPM based map for ignition advance. E.g. with TRE you just use the 5&6 ignition map which is very different to other maps particularly at part throttle areas. There seems to be much more advance on 5&6 map at very small throttle openings where as with other gears it looks like they had reduced the advance, maybe to avoid knock or just keep the front wheel down ? What ever the case, this looks like an area for optimization. With more than 10% throttle opening (30% total TPS voltage) there is not much difference, even though it looks like the top gears runs just a bit more advance even at full TPS/RPM.
For fuel, there is a separate map for each of the cylinders. (and a second set of maps in case you decide to install the map select swithc). Additionally there is a lot of other sensors affecting fuel delivery including injector opening time compensation based on the engine voltage or outside air temperature.
Then about the mystery of ramair compensation. There is actually two sets of ram air compensation maps. Normal load map for all gears 1...6 and a high load map for 3,4,5,and 6th gear. The total difference in injector pulse at around full throttle and 9krpm is about 0.2-0.3ms (have not had equipment to get exact figure). At 9krpm the injectors run around 10ms so its 0.2/10, i.e. compensation is 2-3%. For you guys who run TRE and dyno at 5th or 6th gear this means that your engine is about 2-3% too lean at LSR events (200+MPH). Suzuki seems to consider that anything above 56% TPS (voltage) or above 8000 rpm is high load.
Regarding RPM limiters, there ECU is limiting the 6th gear around 10050 rpm. Normal RPM limiter being at around 10800 and clutched being around 10500. The interesting thing is that there is three sets of limiters. The normal RPM limiters, Gear specific limiters (for top speed limiting) and third set for which I have not yet found a purpose. The maps maps run to about 13.000rpm and ingition maps even a bit higher. So it looks like the ecu is able to run up to appr 13k just by changing the limiters alone. Well done Suzuki for thinking in advance ... this is something I will certainly look to benefit for next season...
Then something more contraversary... Then there is an interesting issue of error codes to be looked more in detail if its just my mistake or something more. A misaligned IAP sensor produces an Ambient pressure FI code and Ambient pressure sensor fault produces an IAP sensor fault code. These two sensors work together. Anyhow it is certain that the ecu calculates the pressure by first measuring the ambient pressure and then reducing the intake pressure from that figure. Based on the result of that calculation the fuel delivered to the ECU is calculated. And then bad news for you guys running powercommanders and alikes. The fuel is always calculated based on the pressure, there is no TPS limit after which the pressure is not anymore taken into account. In practise this means that a TPS based fuel adjustment computer (a piggyback unit) will not be enough for compensating the fuel loads needed for various conditions. Its possible to dynotune something that works very well with fast acceleration on track, but that may not anymore work well under normal driving conditions - and vice versa. This may well explain why some persons are complaining a poor driveability on the street with bikes performing very well on the track.
The above applies only to 2004-2007 busas Euro and USA. I dont have a commercial interest in any of this so the above is just my personal opinion based on what I have learnt by looking inside the busa ecu. Something to be shared to make our bikes run stronger and faster on track...
Part 2 fuel maps.
The busa ecu is quite advanced in terms of how it calculates the fuel for any particular load or other engine condition. It has basically one map for each cylinder for the following purposes:
- Idle map (800-2000rpm)
- IAP map, i.e. vacuum based map
- TPS map, i.e. throttle position based map
When on IAP map the injector flow is calculated in relation to the vacuum vs rpm. Vacuum is calculated as the difference of the ambient pressure and manifold pressure rather than just absolute vacuum. The IAP Fuel maps represent the Volymetric efficiency of the engine (for each cylinder). When on TPS map the injector flow must is calculated in relation to the TPS opening (airflow) vs rpm. Likewise the TPS fuel maps represent the volymetric efficiency of the engine (for each cylinder).
The result of addressing either of the maps above the VE, i.e. volymetric efficiency of the engine. When this result is divided by the injector flow capacity then we get the basic pulsewidth for an engine cycle.
Additionally to both maps there is a need to adjust the fuel delivery according to several other inputs, like:
- external air pressure affecting the density of the air charge
- intake air temperature affecting the density of the air charge
- pressure of air into intake (gear / speed compensation) affecting the density of the air charge
- possible oxygen sensor
- possbile "yoshbox" compensation
- throttle/acceleration enrichment
In busa there is much compensations, but these are the most importants to start with.
These correction factors effect the amount of fuel needed for VE due to e.g. air density change so therefore the results are usually multiplied into the VE.
Despite of all the correction factors the injector opening time needs to be compensated separately. The opening time is dependent on the voltage (an also fuel pressure but that is assumed constant). This number is usually just added to the basic injector pulsewidth based on voltage.
Mathematically the above can be calculated into the following formula where comp1,2,3 are above mentioned compensations.
pulsewidth = comp1*comp2*comp3*(map_VE / injector_flow_cc) + (Injector_opening_time * Voltage_compensation)
Obviously at any given moment the pulsewidth can not be more than it takes for the engine to make full 720 degrees that it takes for an combustion engine to start a new cycle. In terms of simple calculations 12000rpm is max 10ms pulsewidth. Where as 10800rpm is max 11.1ms pulsewidht. Usually it takes up to 2ms for opening time so we are effectively talking about max 8ms effective pulsewidth for a busa.
When raising the rev limiter from 10800 to 12000 the pulsewidht is at high risk to reach it maximum which turns the FI light on, so therefore we need to upgrade the fuel delivery on two fronts:
1) Increase fuel amount, eg. by raising the fuel pressure (crunch the regulator by 0.9mm mod)
2) Increase the inj_flow variable in the busa ecu to make the ecu to understand that more fuel is delivered.
So just updating the fuel delivery either by raising the fuel pressure or by updating the injectors alone is not enough as the ecu still thinks that it reaches the limits and turns the FI light on. This is due to the fact that when reaching close to 100% the injector coil reverse voltage peak that the ecu recognizes as an indication of injector coils being in good shape disappears.
And those who are interested, below is a copy of the K6 Usa model cylinder0 TPS fuelmap (TPS% are absolute voltage%, so appr 20% is 0% opening).
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34 downloadsThe FI light from injectors can indicate several problems, but effectively ECU is looking one thing from an working injector (or ignition) coil. When the voltage is on for a coil it opens the injector, but when the voltage is off there is some residual energy stored in the coil That is released when the voltage is turned off. Ecu recognizes this peak, or rather the lack of it. When the fuel injector coil is on for all the time (i.e. pulsewidth is 100%) then obviously the injector coil is turned on all the time and it can not release this peak energy. That means that after a certain point the ecu can not anymore recognize the coils being healthy due to this missing peak voltage - and the consequence is FI light ;-(.
Below you can see example of the reverse peak voltage that the ECU expects to receive:
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24 downloadsAnd here you can see how the pulsewidth changes shorter when the ECU is reprogrammed for appr 30% higher fuel pressure or bigger injectors (in this case from 10ms@10000rpm, full throttle down to 7.5ms@10000rpm, full throttle:
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23 downloadshe previous message was an explanation how to avoid FI light by reprogramming the ECU. There is possibly also an alternative, you can modify the air pressure sensor (NOT the intake pressure sensor) so that the ecu thinks that the ambient pressure is less than it actually is and then remap all the fuel maps on your PC. Personally I rather prefer just changing one figure inside the ecu than going through the trouble of remapping everything and not knowing if the stuff still works in low pressure.
I know this to work from the workbench, but it has not been tested in real world.
Part 3 ignition.
This is the final part of revealing busa ECU secrets covering the ignition. One of the main reasons why one should consider upgrading the stock ECU is the ability to change the ignition maps to reflect the changes made to the engine. Ignition is the key ingredient in making the most out of the improved volymetric efficiency of the engine.
For example a cam change enables usually more overlap and hence better fill of air/fuel mixture at a particular rpm. More fuel/air mixture compared to a mixture where fuel/air & burned gases (=less VE efficiency) means different burning speed, i.e. different ignition advance. Another thing effecting the VE is a simple modification of changing the throttle bodies changing the VE at certain parts of the RPM band. For me the key ingredient of timing change is the ability to have retarded timing for nitrous usage, something the turbo guys may also appreciate.
K5&K6 (and assume the same applies to K4&K7 too) Busa as such has the following ignition maps when it comes from the factory:
- Gear 1 ignition map
- Gear 2 ignition map
- Gear 3,4 ignition map
- Gear 5,6 ignition map
- Neutral / Clutch ignition map
and all of these are doubled into two banks, one for inner other for outer cylinders. Additionally all the maps have a "spare copy" that can be programmed behind the MS (map select signal), i.e. a swhich that does the map change (e.g. for nitrous or boost). So all together 32bit busa has 20 ignition maps with some adjustments there too.
Alike to the injector coils the ecu expects to receive the coil reverse voltage peak as an indication of healthy ignition system. The coil charge seems to change according to the RPM, but I have not yet found the coil charge map. The coil charge is quite big at lower rpm getting very low at around 5-7k then getting bigger again at around 8-9k. The changing coil charge means that the ecu program tries to keep the coils temperature low and make the coils last longer. So after figuring this out I dont anymore have any reasons to consider an ignition upgrade.... as there also seems to be a map that compensates for a lower voltage in the system.
Some of the maps are very alike, but biggest differences are between map for 5&6 gear vs. the rest. Also there is quite big difference between Bank A and Bank B maps. I suspect there being two reasons for the A/B difference: first at lower rpm the throttle bodies make the VE different between cylinders. At higher rpm the differences are much smaller, but I believe that Suzuki wanted to run the middle cylinders a bit cooler and kept the advance a bit lower. But these are just my personal thoughts.
Even though I am not exactly certain about the exact timing in absolute degrees, here you can see a sample of various maps that K5 Euro Busa has for your information.
Gear2 BankA, note the dip for lean cruising area:
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25 downloadsGear5,6 BankA, note how there is much more torque at acceleration area
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24 downloadsGear5,6 BankB, note how this is different to BankA
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23 downloadsNeutral/clutch map, note how this is only RPM, totally independent of TPS position.
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24 downloadsMore info can be found on the links below.
http://www.bikeland....time=1184107032
http://www.renesas.com/e8a
http://www.activeboa...rumID=99460&p=1
http://macmadigan.no...s_connector.mht
