i am getting like 16 mpg and thats taking her VERY gently. i never go above 3k rpms! i have an 89 305 TBI with 5 speed...is bout 16 mpg right??? (and i do bout 60-70% highway)

 

Currently i am getting 23. I was getting 18 with 90% hwy, but then found my 02 sensor to be bad. i also put in a stage one chip from tbichips.

 

something is wrong if you're getting that milage. My old automatic 305 use to get around 17-18mpg city and 25-27mpg highway.

 

so where should i start? tune up maybe? or should i just start replacing parts such as O2 sensor and adjust timing(because i thinks its off)

 

ah i just found out from the person i bought it from that my cat was gutted..could this be a problem? O2 sensor goes right before the cat right?

 

O2 sensor is just below the drivers side exhaust manifold, and a good running stock TBI 5-speed shoud get at LEAST 20 MPG avg. and can get over 30 on the hwy. Replace the O2 and give it a good tuneup, if you advance the timing a few degree's from the stock setting of 0 you will get a little more power and MPG out of it. A gutted cat is bad too, after my cat went bad I gutted it and MPG took a nosedive, It also sounded like crap, I replaced it with a straight pipe and MPG came back and it sounded much better.