Good stock ECU writeup?
Good stock ECU writeup?
Does anyone know of a really good writeup on how the stock ECU works? I tried a few searches, both here and on Google, and didn't come up with anything other than people trying to sell me mail-in flashes.
What do you need to find out exactly ? If your really that interested invest in a tactrix cable from tuner tools to access your ecu through your OBD-II port and get yourself ECUFlash from Open Ecu and either get Evo Scan there for 25$ or go to Aktive Matrix and dl Mitsulogger all you need to do is register there and its free.
With those youll be able to log what your car is doing and change what ever you want in the ECU table like AFR and timing along with many others.
Also you'll want to invest in a Wide Band o2 Censor and Logger before any of that so you know how your car is running air fuel wise. Check out this site Dyno Tune Nitrous. I went with the Innovative LC-1 which most loggers support.
With those youll be able to log what your car is doing and change what ever you want in the ECU table like AFR and timing along with many others.
Also you'll want to invest in a Wide Band o2 Censor and Logger before any of that so you know how your car is running air fuel wise. Check out this site Dyno Tune Nitrous. I went with the Innovative LC-1 which most loggers support.
I was looking for something a little more theoretical. I'm planning on getting the package from Innovate in a few months but I'd like to know how the ECU does what it does from a controls engineering standpoint before I start monkeying with stuff. What is the I/O? How does it calculate demand and fuel delivery? How does the boost control work? When is it in open loop and when is it in closed loop? What does the feedback loop consist of for fuel? For boost? I'm looking for a pretty hardcore engineering writeup on how it runs the motor.
Fuel delivery is calculated based on MAF reading, air temperature and barometric pressure ... all of which are monitored just after the intake filter. There are scalings and correction factors for all of these values in the ROM.
Boost control is based on load, which is again based on MAF, barometric pressure, and probably a bunch of other stuff. You set a desired load value for a given RPM, a static load offset value, wastegate duty cycle percentage, error compensation, load limit and load limit timer. All of this culminates to control of the boost which is actually based on a completely different load value than the fuel and timing uses ...
The open/closed loop transition is based on TPS to RPM or load % to RPM ... whichever is reached first. This can be changed in the ROM as well.
Anyway, what it comes down to is that you really don't need to know exactly how the ECU technically communicates and parses all of the data. You simply need to have a good understanding of EFI and forced induction tuning principles. After that, it's just software.
If you increase the value in the fuel map, the mix will be leaner. Does it matter if you know all of the 14 values calculated to make it leaner if you can only control the single value in the fuel map?
Yes ... sometimes it's good to know. For instance, if you modify the MAF scalings, those changes will affect nearly everything else that the ECU controls since so much is based on the MAF reading. But, in the end, everything will also be offset by the same value. So, you'll likely not even notice a difference since only the closed loop fueling will really be affected.
In short, don't worry about it. 99% of the time the changes you make will have nothing to do with how the ECU interprets the numerous voltage signals it receives.
Boost control is based on load, which is again based on MAF, barometric pressure, and probably a bunch of other stuff. You set a desired load value for a given RPM, a static load offset value, wastegate duty cycle percentage, error compensation, load limit and load limit timer. All of this culminates to control of the boost which is actually based on a completely different load value than the fuel and timing uses ...
The open/closed loop transition is based on TPS to RPM or load % to RPM ... whichever is reached first. This can be changed in the ROM as well.
Anyway, what it comes down to is that you really don't need to know exactly how the ECU technically communicates and parses all of the data. You simply need to have a good understanding of EFI and forced induction tuning principles. After that, it's just software.
If you increase the value in the fuel map, the mix will be leaner. Does it matter if you know all of the 14 values calculated to make it leaner if you can only control the single value in the fuel map?
Yes ... sometimes it's good to know. For instance, if you modify the MAF scalings, those changes will affect nearly everything else that the ECU controls since so much is based on the MAF reading. But, in the end, everything will also be offset by the same value. So, you'll likely not even notice a difference since only the closed loop fueling will really be affected.
In short, don't worry about it. 99% of the time the changes you make will have nothing to do with how the ECU interprets the numerous voltage signals it receives.