So why don't we have self-tuning cars? I would think that this would be possible. The way it would work, is you'd buy an EMS for your car, and it would come with a base map and a wideband. All you do is enter a target AFR, and based on the input from the wideband, the computer would calculate how much fuel would be needed to achieve that target AFR. The hardware wouldn't cost more than a currently available EMS, but the big savings would come from not having to pay someone several hundred dollars to tune your car. Also, it would be far safer and more precise than any human could tune a car. What would be some of the issues with this?

Because there are multiple things that need to be taken into consideration. You are only thinking of A/F ratios. What about timing control? What about taking different injection systems into account. Most nitrous, water, alky, propane systems are designed to kick in at different times + rpms, AND they would also screw with the A/Fs. Octane levels would change with different fuels.

Plus what would be the margin of safety? Most stock ecus have a certain knock threshold they will accept. If knock levels are lower, they will advance timing. If knock counts are too high, they retard timing. You would have to program your own thresholds.

It would be too many factors for the 'computer' to automatically figure out and tune for.

In a way they do kind of keep them selfs tuned already.

uhh yeah cars already do keep themselves tunned. They just cant drastically tune themselves. Thats why you can take a car thats already turbo and up the boost and the car will compensate for the extra air within its abilities. Same thing the car does when its warm and cold outside, it compensates for the extra air or lack of air.

The problem is, the car can only be designed to tune within its factory parts. Once you start adding non factory parts it has no idea how to tune it, because it doesnt know what the part does. Like in intake or example, now the 02 sensor should be able to adjust for the extra air coming in, but it cant adjust for the velocity of the air.

Also take timing for example. A car has the ability to pull timming due to the knock sensor. And its extremly aggressive. Once a car feels a knock it pulls timming something around 10 degrees i believe. Then it adds timming at the rate of one degree per 30 seconds or something like that. Well the system on MOST cars is designed to only run 87 octane. So the car can only pull timing. In order for a higher octane to have an effect on the car, the enginers would first have to create a way for the car to know its running a higher octane and second they would need to write a program to add timming when possible. This would be a feature that 90% of the car owners wouldnt even car to use, becase lets face it, most people want to save money by pumping 87 octane. So all the extra enginering and programing would be a waste for the most part, but prolly add a few more grand to the cost of the car.

Also like stated before, cars have no ability to tell what size injector they are using, and they can only do read so much with the stock sensors, which on 95% of cars isnt much. And on prolly 90% of the cars is more than enough for the average driver, which is who they market cars for.