I don't suppose you've had a compression check done lately?

 

I get 27 with tons of warm up time. I'd look to other issues.

 

My milage dropped about 8mpg over the winter so I seafoam it which helped a bit. Also for those who have CAI or SRI and aftermarket exhausts check to make sure you exhaust manifold isn't cracked. It's common in 96-00 civics and all you have to do is take the 2 bolts off of the headshield by your header. Then you can see whats going on. As my mechanic described it to me, with out CAI or SRI and aftermarket exhausts you'd hear a FA FA FA FA FA FA F*$% noise and that's when you know you're in trouble. I couldn't hear mine due to sri and my catback but when i seafoamed it it was smoking from my o2 sensor.

 

I second the exhaust manifold... mine cracked and then I patched it temporarily (too hot to stay for long) and my mpg jumped by like 5 mpg. Gonna replace it either end of april or when summer break starts.

 

Really? i didnt know and exhaust leak could hurt mpg... i guess i should look into a header (id rather do than than replace the broken bold on the downpipe.... upgrade as it brakes strategy)