[EcoCivic]

My 2005 Civic VTEC with an automatic transmission is, for some reason not getting as good of gas mileage as it should. I have done a few things to it in part to improve mileage. It has a power steering delete, AC removed temporarily, new timing belt, minor weight reduction, almost new LRR tires filled to 40 PSI on alloy rims, all LED lighting except interior and reverse lights which will get swapped too, recently I fully rebuilt the engine, high flow header, cat and muffler, D16Y8 intake manifold and fuel injectors, custom air intake system, and a couple other minor things. It only gets around 26-28 MPG. I checked all the sensors and it has a new thermostat. It runs very well, but not very efficiently. The only things that I can think of that might be contributing is a crack in the exhaust header, the EVAP purge valve is stuck closed and it is missing the front wheel well liners, but I will install those soon. Any ideas? If you have any questions or things to check, please let me know. Thanks a lot.

UPDATE: The last 2 times I filled the tank after I installed the wheel well liners and JB Welded the crack in the header I got 31.5 and 33.7 MPG on my last 2 fill ups. The first tank was a decent amount city driving, and the second tank was more highway driving. I might be able to get the mileage even higher if I fix the EVAP purge solenoid, fix the problem with the o2 sensor intermittently going dead and possibly reconnect the EGR, although I do not want to cause more carbon buildup in the intake and cylinders by pulling in dirty exhaust, so I probably won't reconnect the EGR unless I can keep the carbon out of the intake somehow.