I recently got rid of my 20-year old cats due to a problem with extreme hesitation... which cured that problem. Course, now I have a new one.

My car was getting close to 18mpg with mixed city and highway driving and not necessarily being babied but not getting on it alot either. Since removing my cats, my economy has dropped below 10mpg. In fact, i'm at 90 miles now and due for a new tank.

I haven't checked anything yet, but intend on checking my tps, water temp, and o2 sensors tomorrow. Anything else you guys can think of that would affect it so I can check it all at once?

 

maybe the old cats were so old that the filter elements (whatever they are) just broke down and the whole thing turned into kind of a midpipe. But now that you have new ones, its more restricted and harder on the motor?

 

When I say I got rid of my cats, I mean there aren't any on the car anymore. In their place is a test pipe and a silencer, so flow should probably be less restrictive rather than more.

 

Sounds like the AUX ports are stuck open or opening way too soon IMO. What silencer did you go with?

 

did you get rid of your o2 sensor?

edit: just read that you still have it. i would check their first