A few questions.
 

Hello everyone! I have some questions, I know a little thing or two about cars however I don't know it all so I need to learn.

First, what is a good A/F reading for my 2003 evo 8. If mods need to be listed for better answers I can reply with such.

Second, what is this and what does it do?

http://img703.imageshack.us/img703/8...2728335183.jpg
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Thanks for the help! {thumbup}

That bolts on to the radiator fan which it looks like yours was taken out?

Nah I still have a radiator fan, and that little black box is plugged in and everything, just not bolted anywhere.

http://farm4.static.flickr.com/3376/...6506cf2b8c.jpg

N

The little black box is your fan control module. They've been known to go out around 70K+ miles. You'll know its broken because the fans will always be on especially during cold start up and even a few seconds after you turn off your car<<< but every time you turn the car off.

In terms of AFR, it depends on your mods and the type of tune your going after. While cruising you can be as lean as 15:1 to help improve mileage and 10.5-11 at WOT on gas. E85 users run richer at around 9ish:1 I believe. <<< Correct me if I'm wrong.