Config and tables related subpage of GenBoard/UnderDevelopment/FirmWare
More bins
upto 16x16 is possible, (14x16 or 15x15 requires no MegaTune changes) but testing and MegaTune support is needed
With the
- applied interpolation
- configurable (not fixed) bins
- 16 RPM bins is enough for the VE of most spiky race engines. 8 is perfect for most. We have never ever had a reasonable complaint with 12 bins
- VE or lambda tables should not have such breaks in the MAP direction in any case (0 break normally, and max 1 break if injector opening is misconfigured)
- More than 8 MAP bins (ignition/VE/lambda table) does not make possible to tune for better power, even for highest boost engines. 12 is more than enough, even when a blending AlphaN / speed-density is tuned, or if the tuner choses the bins somewhat unreasonably.
- ideal ignadv has 2 breaks in MAP direction, for which 4 MAP bins are needed. The extra 4 bins can be used to smooth out all areas, or spare bins to insert anywhere. The common misconception "more bins needed for high-boost engines" comes from bad injector-opening values (often the lack of proper injopen model in most ECM-s). See GenBoard/Manual/Config/InjectorOpening,
For marketing reasons 16x12 or even 16x16 might worth to consider. This is MegaTune configuration issue, though the firmware also needs to be recompiled and tested.
It is possible to approximate the ideal maps beyond measure errors with 7x6 (for a high-boost engine with many bumps in the torque curve), or even just a tiny 4x4 for the lambda-target (millions of engines with NBO2 use 2x2 or smaller), but:
- VE on variable valve timing or variable intake motor depends on the switchover point
- during tuning, it's easier if an intermediate bin can be easily inserted on demand
- Programmable Injection timing.
Injection timing angle when the injection firing ends (0-720 deg) from the TDC, at every RPM bins (only depends on RPM, not MAP).
fixed injection start angle is useless -Jörgen
I mean programmable injection timing according to the RPM bins -Fero
MegaTune is limited, 1/x conversion is not possible
Would be needed for lambdatarget=>ECU.
- We can make a "view" that is a new page: reading/writing is still from/to l table, but conversion happens (with the help of div_65535_x() ) during read / write (not direct values).
- some extreme values:
| lambdacorr | internal_lcorr=lambdacorr+200 | lambda | meaning | 65535/internal_lcorr | optimal megatune value |
| 0 | 200 | 256/200 = 1.28 | lean | 327.68 | 255 |
| 56 | 256 | 256/256 =1.00 | stoich | 256 | ? eg. 183 |
| 255 | 455 | 256/455=0.563 | rich | 144.03 | 0 or higher, eg. 71 |
The recommendation for the conversion involves an offset of 72 or 73:
- lambda_mt = div_65535_x( internal_lcorr ) - 73
- internal_lcorr = div_65535_x( lambda_mt + 73 )
- matfactor.c: MAT sensor ADC to MAT internal format (eg. 0..255 means -40 .. 215 Fahrenheit) conversion
- thermfactor.c: CLT sensor ADC to CLT internal format
- airdenfactor.c: MAT sensor reading to air density correction factor (100 means *1.0, 110 means *1.10 fuel pulsewidth due to appr 30C lower MAT temp).
Naturally, thermfactor.c and matfactor.c are similar (with similar NTC based sensors, like used all over, GM, Honda, BMW, and every manufacturer). These are monotonous (except limp-home "bad-sensor-assumed" values at the end of the scale).
airdenfactor.c is different, it comes directly from the universal gas law.
- airden_ignore=62 // Suggested value=0x62 (decimal 98). Indeed invented to solve the "idling heat soak" problem, by not allowing to lean out the mixture too much at low RPM. 0 disables altogether.