I have a 93 LX,5-spd,with 209K miles. For about a year,the best I've gotten is about 36mpg. I use to get about 38 or more with ac on and 43 with ac off.

It runs fine. I was wondering if the O2 sensor or the cat may be causing the loss. Any ideas?

 

What general maintenance have you done?

 

43mpg?!?! are you sure?

 

Depends on the weather too. COld air is more dense with oxygen so you might see a drop temporarily.

 

this is why i hate winter. gas mileage goes down and im broke . and hate snow and cold weather. /end rant

 

I replaced the fuel filter a few months ago (Wix) and plugs(Bosch Platinum +4) last year (they always look good)...cap and rotor are probably about due. The thing is,it runs really well,like always.

I've heard that cats get restrictive over time and that the O2 sensor can get "tired". Thw decrease has been in hot and cold weather.

I have the factory maintenance manuals;haven't really t/s it yet.