Ef2 with d13b engine.

[kakaroto_ss4]

OK people i have a ef2 with a d13b from honda logo engine i don't know how many mpg i get with this car and i need some tips to tune up this engine to get more mpg and how to calculate it.

some problems on my engine.

Gas odor (sometimes)

O2 sensors disconnected (the two)

Now some spec.

2" downpipe but i in the header i have a 1" or 1.2" pipe solder to the 2" pipe to the exhaust.

D15b Tranny.

Ok now i need to know i wanna a new header a 4-2-1 do i will get better mpg on a new one?

and what about my engine its this good for my car i mean its a civic hatch si 90 its not to heavy for the engine?

well i just want some help please.