I have a 99 EK, LS swap with a GSR trans. Just got it running 2 months ago. I've noticed my gas mileage is complete ****. With a full tank, I'm getting about 200 miles. Is this the norm?

 

How are you driving it? Any codes? Does CEL work? How are tires? How are you calculating mileage? Has O2 been replaced recently?

 

I barely ever take over 5K. Tires are new, just got them in August. I don't think my sensor has been replaced, but I calculate mileage based on my trip. Is there a more accurate way of doing it?

 

When was the last tuneup this engine had? Check timing? How long was it sitting? Bad gas?

 

Nope, I mean just top up and divide mileage by amount on trip.

What kind of mileage is this? City, highway, mix? Even for all city, 20 seems low for me but I'm no expert. I know driving my y7 kinda on the harder side, I get 26 city.

Does your CEL work and have you checked for codes? How does it idle? Any performance issues? Running rich? How is timing?