ECU Logic explanation
ECU is working with such known term as "Load".
Depends on "Load", ECU request some amount of boost.
Boost it is what gives us power.
admin@flashex-tuning.com
When driver is pressing on acceleration pedal, he is working with Torque. There is an characteristic in ECU to convert acceleration pedal value to requested Torque.
After receiving Torque request, ECU convert it to requested Load. Load is converted to Boost Target, and turbocharger will spinning, until reach target.
In short, this how ECU is working.
1. Max Relative Filling(Load)
One of the most important part of firmware, and this is how you can increase power
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- Maps choosing minimal value from maps "1"(Maximum compressor pressure ration) and "2"(Surge limit). Multiply it on Pvld(pressure before turbo-charger).
- Minus "Dpllk"(pressure drop on intercooler).
- Map "3"(residual pressure) multiplied on some "Height correction factor"(not interesting in our case), leave it in stock.
- Minus this value from value on previous step.
- Map "4" - Relative Filling Factor koefficient multiplied by "F_tzylkor"(temperature correction).
- Result RF from step#4 multiplied by corrected Relative Filling Factor by temp(from step#5) and acquire result Max Relative Filling!
- (Important!): Map "5" - max relative filling due to ignition retarding.
- Last step: choosing min value between this two results
2. Inner Torque
Choosing torque map depends on gearbox type(1 - Manual, 2 - Automatic, 3 - DCT)
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- Choosing torque map depends on gearbox type(1 - Manual, 2 - Automatic, 3 - DCT)
- Acquiring max torque from map1 or 2 or 3.
- Minus "Mdi_reib_vl"(see section below)
- Applying correction coefficient by intake air temp(Map4).
- Applying correction coefficient by motor oil temp(Map5).
- Applying correction coefficient by ignition retarding due knock(Map6-7).
- As you can see, we are leaving all coefficients and axis as in stock.
Many other tuning companies is filling all this temp coefficients with "1" to not restrict car's power sacrificing engine reliability in such case
3. Torque By Gear
Inner torque can be limiter per gear
- Map1 and Map2 are the same in firmware, so changes will be equal.
- Just increasing max possible torque values.
4. Friction losses
On previous step we are calculating inner torque.
Overall torque will be inner toque + friction losses.
Friction losses are calculating via next logic:
- 1. Friction losses per coolant and oil temp(Map1/2).
- 2. Friction losses per Load and Rpm(Map3/4).
e.g. 60 coolant, 60 oil: from Map1/2 receive - "-5.70 Nm".
Max Load(200) at 5500rpm: from Map3/4 receive - "-82.60 Nm".
Our result friction losses will be "88.30 Nm".
5. Result torque. Important!
Result torque is torque - mb_reib(friction losses).
Out result torque will be 450 - (-88.30) = 538.30 Nm
This value is going to one of the main table in all ECU - "Torque to Load Conversion".
Firstly, this table is telling ECU how much Load we need per appropriate torque.
Secondary, it is also torque limiter, so if your torque + friction losses will exceed value in this table - you will not receive more power.
As you can see, this table is calibrated up to 220 Load, and 540 Nm torques.
And this is how we can unleash additional power which is already stored from factory.
- 1. Here we are not doing any changes, because everything is calculated for us from factory.
- 2. Values in "Sport Display" of your multimedia is taking from this table.
This is another option how some tuning companies are cheating.
They are modifing this table, and your are seeing great values on screen, but there is nothing with real values...
6. Boost
Compressor map is also scaled up to 1080 kg/h air-mass and 1.9 relative boost.
Stock 28i engine is running at 700kg/h and ~1 bar boost.
7. Ignition
Ignition angle is also calibrated to 200 Load.
It can make sense to extend it to 210 Load which we are using and reduce last row by "-1" degree, but I think it won't greatly affect on engine reliability.
(other tuning solutions are running on much more aggressive angles even for stage1 and 91 octane).
It was tested on road and on dyno - there is no knocks.
8. CONCLUSION
All this changes is enough to increase engine power.
And want to remind: all other parameters leave as stock, so you will have factory behaviour of your car, with increased power.
Below, it is a dyno result for current firmware(BMW F30 328i).
