i have a 92 civic vx , the fuel economy is about 32.5-37.5 with a 5 to 1 city/highway , i would like to get this average to about 38-40 ala factory specs



since i bought the car last winter have replaced

- new oem fuel pump
- new oem fuel filter
- new braided fuel line
- cleaned and remapped oem fuel injectors
- new oem fuel regulator return valve
- new oem spec ngk spark plugs gaped perfectly
- new ngk coilpack/cables
- new distributor
- new oem timing belt
- new oem water pump
- new temperature sensor
- new ecu
- new oem iacv
- new battery
- new axle back exhaust
- new intake filter
- new driver side axle
- throttle body thoroughly sprayed with throttle body cleaner
- tires 42psi+
- egr "scraped" new gasket

even with all these "refreshments" i can still feel the power cut out or "sputter' for a mili-second when cruising at highway speeds i feel like this maybe directly related to my lack luster economy

the 02 censor looked brand new when i bought it , the only thing i can think of that i havent replaced yet

- egr
-cat converter
-new front brakes and wheel bearings to reduce rolling resistance

if there and any other suggestions for things that i missed to get my fuel economy where i want it that would be much appreciated...

 

If you're saying you drive 5 miles city per 1 highway, overall mpg in the high 30's seems quite good.

Yes the O2 sensor is essential for the VTEC-E lean burn to work properly. And they can cause runnability / mpg problems without setting a code. An exact replacement is important. It is a special wideband design.

There are other forums where the members are really dedicated to their VX / HX and tuning it for best mpg. Typically they call themselves "ecomodders."

 

There is a hiccup on a VX whilst driving ... it's normal like when the VTEC-E component engages or some such. Clean that EGR though, as well as the intake(?) ports, or whatever they're called on the intake manifold. Requires some drilling and aluminum plugs.

Also it matters if you have a 4-wire or 5-wire O2 sensor. The four-wire was California-only and gets worse fuel economy.

 

a new O2 and valve lash adjustment were the two things on my VX that made the largest differences.

5/1 city/highway mix with a 38-40mpg goal. Your right foot had better be pretty light and your speeds shall not be greater than 60mph.

When the 'lean-burn' mode shifts in and out you feel a slight stutter in the power output.

 

Low Rolling Resistance (LRR) tires should improve your average mpg. I previously had LRR Michelin Energy Saver tires on an Accord and it consistently averaged at least 3 mpg more with mixed city/freeway driving when compared to non-LRR tires.