Not sure if this is the right place to post this, so here it goes. Okay all you tech savy guys. I have a weird situation with my '03 Evo. This will be long but I have to give you guys all the info, so here it goes. As some of you know, I have a ScanGuageII hooked up to my OBD port. It displays alot of info about the going ons of the engine like rpm, speed etc. and can also reset any trouble codes that may pop up, which is great. It also has a function that tells me how much MPG I am getting, usually @27MPG. So as you know the '03 are notorious on the PO300 code and since I can reset the code on the fly, it was a great function. After a while of getting the code and resetting it, I finally said "f*ck it" and have the check engine light on. So after driving the car off and on for @ 2 months the check engine light went out. I thought the damn light was burned out but it wasn't, it still lit up and turned off when I start the car. Now here is the weird part. I noticed that since the light went out, the car is using less gas. So I check the function on the ScanGuage and this is what I saw:


Is the ECU running the car lean? but damn, that's too lean if it does. This happened to me before and when I reset the ECU the car uses the "normal" amount of gas. This time I haven't reset it yet and wonder if I am doing any damage. The car feels fine and strong. So what gives guys. One last thing, I compared it too to the gas gauge and noticed also that the gauge hardly moves. Example with a full tank of gas I would go from my house to work(@40miles one way) and the needle would be near the 3/4 line. Now same distance, the needle would be just off the "F" letter. This is Weird!! To me it seems like, if you don't reset the ECU within a certain amount of time, the ECU would disable the PO300 signal itself.