IndecisiveS197

I figured that much, but if variation from stock settings is what people are concerned about what I don't get is why people are so scared about problems.

Adding a higher flowing air intake can change things, but I'm sure a car in the middle of winter at sea level and a car at a much higher elevation in the middle of summer see very different amounts of air, and the factory ECU can handle these vast changes quite easily.

Is it honestly that the Factory ECU will not be able to cope, or is it just that the improvements from the tune make it so much more worth it?

I know I may be coming off as sounding like a stupid noob, but I find it baffling if it's a case where the factory ECU cannot handle a change that's as small as having more air through the system. I've switched to a much larger turbo charger from factory on a stock ECU w/o having issues(the ECU was able to compensate easily...actually running a bit rich) on my old nissan. Yes a tune would be the best thing to do to create more power obviously, but like I said, I find it hard to believe that the Ford factory unit wouldn't be able to cope.

jimkaray

Think of it like jail breaking your iphone. You're right that the ecu can handle a lot of variation and it does. The flexibility and processing power isn't the issue, its the strength, if it wasn't a custom tune wouldn't do much. The issue is the narrow error margin allowed by the factory before the system reports an error and turns on the check engine light, or worse goes into safe mode. A custom tune replaces the factory programing so it is aware of the changes made and optimizes the settings for them and adds other performance tricks. Nothing is perfect and each car different so you could introduce a problem where there wasn't one before. On occasion there are issues that need to be worked out with the tune shop sending you a revised tune/s until it is right for your car. No different then the factory updating their tune for known issues.

IndecisiveS197

I forgot this is an OBDII car...heh(it's my first), which is more sensitive to parts changes.

It makes sense to me now. Thanks for clearing it up.