Decreasing MPG
 

New to the forum, so bear with me.

Car is 03 Accord EX V6. It failed emissions for O2 sensor, v-tec oil pressure switch and throttle body issue. Replaced O2 sensor, Oil pressure switch and cleaned throttle body. Vehicle passed emissions with flying colors. However, now I find I am getting an average of 2-3 MPG less than my regular average. Looked over every connection that I touched during disassembly and re-assembly and did not see any connections that were left un-done. Any ideas?

Kind of a hard one here....directly related to the work done or did it bring it to light? How are/have you been calc the milage, sorry I have to ask but I've been bitten before.

Anyway, are the plugs up to date? What brand O2 was installed? Then we are all dealing with "winter blends", at least in the US.

I am guessing directly related to the TIMING of WHEN the work was done. Again, I know for sure, that I put everything back together fine. No parts left over is good....right?....:p:p Was getting 27 overall mpg according to my in-dash computer system/navi prior to the work getting done. As soon as I did the work and re-tested with emissions, I noticed that I am only getting 24-25 mpg overall. Was getting as high as 31 mpg on way to work, now can't get it above 28.5 ish.

Bosch O2 sensor. Duralast oil pressure switch. Plugs are original, never been changed, 204k miles. This all took place in 1st week of Jan, so I was using the same blend of gas before and after.

Check Long Term Fuel Trim w/ scanner. If excess fuel is being injected, the LTFT will be negative meaning injector open time is reduced to reduce fuel flow and achieve desired air:fuel ratio.

If LTFT is near zero, then fuel is being metered correctly and some additional load is causing higher consumption. Check brakes, tire pressure, alignment.

If you're correct in calcs, fuel consumption has gone up about 10%. I suggest watching a few more tanks w/ manual calcs to check your vehicle computer results. I've never understood how this system is calibrated orginally, or even if it is calibrated.

Have tires been replaced w/ larger tires? This will cause an apparent increase in fuel consumption.

good luck