Well i got my b20 swap in but different things come up everyday. I realized that I was only getting like 15 miles to the galon. I got a gsr tranny and an ls final drive but that still wouldnt be the case. Anyone think it is the O2 sensor or whatelse?

 

whens the last time you did a tune up? plugs,wires,filters,ect...? it could be your 02 so i would change that as well

 

Well i bought the motor off ebay last winter for a fair price and I guess I never really checked any of that kind of stuff... i was to excited to get it going. What should I all check? I'm guessing O2, fuel filter, and i don't have any ideae what else. I'm not the oldest kid on the block lol. Thanks

 

Get a new Denso O2 sensor, decent cap/rotor, OEM/NGK plug wires, NGK plugs, ait filter (replace paper/clean cotton), and obviously change oil&filter if needed. Don't feel bad though. I reused the +2yr old NA plugs on my boosted motor for 3k miles. I only changed them because they didn't like anything over 13psi

Check the compression numbers if you can, tired rings can affect performance and MPG's.