There are a lot of resources, my favorite site is EFI101.com they offer schools and have a lot of info involving tuning, tuning equipment and there are a lot of programmers on there that get very in depth about how the electronics work and everything. There is many different aspects in tuning electronics, there are some insanely smart guys on there that have built systems for super cars that can monitor everything going on and adjust for it in each cylinder. I would start there as you should be able to learn more than most will ever comprehend but there is also enough well informed people that should be able to answer even the toughest questions.
There are a lot of guys on here who can help you out with specific tuning questions and even on some of the systems but I think overall its very hard for any of us to teach you everything about tuning especially on a broad basis. There are so many systems, setup and different configurations I wouldn't know where to start. I enjoy the tuning side more than anything and would be happy to help if I can, however I need to have some idea what type of tuning you are looking at, and then go from there. If you begin to study and then jump back on here with questions I think with the guys on here we should be able to get you an answer. Tuning is a very broad world with a lot to learn, but when you break it down its really not that hard once you get the basics down and have some electrical knowledge.
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