c1civic

ok first the details. i have a 97 civic ex 4dr auto which spun a bearing in my y8at 127k. before that i average about 27-29mpg I ended up swaping a d16y7 longblock in its place because i not find a y8 locally. I am using the y8 harness, y7 ecu, y8 auto tranny, y7 complete longblock, y8 intake mani with y8 tb. THe ca\r has a had a cel on for secondary o3 sensor for over 2 years with no probs to performance or gas mileage.

Things that are new
primary o2 sensor
fuel filter
plugs
plug wires
cap
button
axles
air filter
also switched out to a diff map sensor

I am averaging 22 mpg, i never go over 3500rpm, its my daily and my commute to school everyday is 70 miles. I still have the cel for the secong o2 sensor. Could that be the problem. Also not sure an o2 sensor would even help since i have a y7 ecy abd y8 harness since the o2 sensors are in diff spots.

please help me, any input is greatly appreciated,
thanks

:Andrew

what is the mileage on the y7?

Otherguy

its the o2, you might be running rich

c1civic

22,000 on the y7, clean as hell, 190 compression on each cylinder. Just did not think it would be the secondary o2 sensor because i did not have the prob before

c1civic

anything else.... jsut filled up and got 19.5mpg!!!!!!!!!!!

jdm_bones

iTrader: (5)

check for exhaust leaks...do you have any mods? If so what are they?

c1civic

100% stock
no exhaust leaks

AK94GSR

do u have the stock cat on from the y7??
if so....those are known to crack due to high temps from
the cat being intergrated in them
remove the heat shield and check if so
this right there could cause the rich condition

i have this same problem

big-cat

im surprised if its not the o2 sensor. when i didnt have mine in. i got gasmilage like 19.5 and i have basically the same mods as u.

pretty sure its ur 02, just get it fixed a.s.a.p, because its costing u more at the pump then just buying an 02 sensor.

c1civic

i am using y8 exhaust mani, cat and exhaust so that is not the problem.. WOuld i run into any probelms with the second o2 sensor. Since they have diff part numbers for the y8and y7, which would i get????????