While i was swaping my AEM intake to my V2 intake for my DC5 and i forgot to unplug my (-) terminal from my battery and no key was in the ignition. i swaped it out and when i turn on my car the CEL light turned on... so i figured it was beacuse i unpluged my Air mass sensor... so i hit up my Fuse box and reset my ECU... but now my gas mileage is like 245miles on a Full tank... before i use ta get like 275-280ish.... n e idea's ?? busted Airmass sensor ????

 

Are you talking about the intake air temp sensor? Is the CEL still popping up? Are you sure you aren't flooring it more than usual?

 

If you had an AEM Cold air on I'm wondering why you would put on a V2 of all things? But it could be the filter, they can make or break gas mileage. Get a K&N with an inveted cone on it and the mileage should go back up. If not put the AEM back on with the K&N filter. How long did you leave the fuse out to reset the ECU? Should have been left out for about 30 minutes. I have on an AEM ca with the K&N and I can get over 350 miles per tank easy.