I only get 8-9 mpg in this vehicle. Recently, i have changed my brakes/rotors, change oil every 3k miles, changed fuel filter, cleaned fuel injection system, changed antifreeze, changed muffler and catalic converter. I am frankly tired of spending money on the gas this vehicle takes. Its one of the reasons why i use the cavelier most of time. Anything i should be checking on? I don't know understand when you guys say "codes". How do i check code problems. any good links to refer to about the lumina ltz? any help would be appreciated... thank you

since you said you recently did some brake job, ok. make sure brakes are not sticking to your discs or your parking brake is not set to tight. The best way to check that is to lift the car and rotate wheels by hand or you can simply see how your car rolls when you shift in D and release brake. If your lumina rolls easy chances are your brakes are not sticking. Also when you start your car in the morning you can smell that rich exhaust, now that is open loop exhaust smell, if your exhaust smells the same way all the time you have problems with o2 sensors, if your temperature gauge is not showing any temperature increase then you have bad ECT sensor. Also check for vacuum leaks. Change your air filter if bad, inflate your tires to 33psi, clean your trunk, make sure your wheel alignment is ok, sparkplugs and wires should be in good condition, and the most important one is use vacuum gauge raise your rpm to 2500 for 30 seconds, observe gauge if vacuum starts to slowly drop durring 30 sec you have clogged CAT. I hope you do not have any internal engine problems.

thanks for the response. Imma be honest, i didn't understand alot of the things you mentioned. Im prolly the biggest noob when it comes to under the hood.... so rev my engine to 2500 for 30seconds, and what vacuum?