MOONDOGGY wrote:Here's a question for ya Rob...
I'm a youngin, but as far as cars go, I guess I'm kinda old school. ECU adjustments and computers mods scare me! I hate even replacing a blown fuse on a newer car! My question is, what kind of programming do car ECUs use? Is everything written in a 'syntax-based' code like Visual Basic/C++? Or do they have their own automotive language? I'm assuming it's not as simple as machine control PLC ladder logic.
I know you can get those adapter kits that you plug in line with your car's ECU cable that then plugs into any PC. And I'm assuming the included software makes it fairly user-friendly. But, just how easy is it to go in and change your car's parameters to say, adjust your torque curve or shift points? Do cars come with embedded limits so you can't accidentally tell a car's computer to shift at 9K RPMs???
Lastly, is there a standard in the auto industry that allows one of those ECU cable/software kits to work with all post-80s makes and models ranging from Ford & GM to Honda & Nissan to BMW & Mercedes?
The ECU in the 2002-2003 WRX is based on a 16-bit 68HC16 processor, everything up to the 2007 use a 32bit Toshiba processor that I'm not too familiar with (since I don't have one to play with
).
To do any programming its in assembly like Ron said. You just have to be really darn careful not to get into infinite loops and such. Although the only way to 'brick' the ECU is for the flash memory itself to physically go bad during a write op.
Any device that sits between the ecu and the sensors/actuators (piggy-back) won't be entirely accurate if the car's ECU does any kind of learning or real-time adjusting. But they are the cheapest and usually work well enough for HP increases less than 33% over stock.
ECU reprogrammers/flashers work quite well in the 33% - 133% over stock range. As long as you're keeping the same basic engine config and only doing mild cams, etc and not adding forced induction or nitrous.
Stand-alone replacements are only if your target involves changes to basic operation (forced induction, nitrous, fuel injection on a carbed engine, etc), extreme cams, etc.
Any embedded limits will vary with each step through that.
A 'piggy-back' device usually keeps the stock limits as far as redline, cruise afrs, etc.
A reflash has access to all that and it is quite simple to change just about everything. Since the ECU only does what your tell it to, it can be a real double edge sword. But there are so many options in a modern ECU that its actually quite powerful. Bonus is you also get a decent base-map that you know works on your car
For example on the WRX you have access to everything from injector flow, to fuel tank pressure (not just fuel pressure, the pressure of the tank itself), to what position the fan switch is on for your heater, and everything in between.
There is software available for free to change all the parameters, 2D, and 3D maps on the WRX. Its as easy as picking the table you want and typing in the values you want. They are all clearly marked and just about the whole 16-bit ECU has been disassembled and mapped.
Stand-alone's are just about the same ballpark as reflashes, except you have no starting point other than your knowledge. No timing maps, no fuel maps, nothing.
Very few consumer level cables/interfaces can reprogram all makes and models. Until the recent agreement/law to switch to a CANbus interface, there were 3 interfaces in use between all the manufacturers and a provision for them to create their own in-house interface which just happens to be the interface most ECU's are reprogrammed over.
Thankfully the government required all manufacturers in 2003 to not only allow programming of basic functions via the CANbus but also they had to release (for a reasonable fee) the complete method and ability to reflash their ECU's.
