I've a new to me 2007 Accord V6. I was suspicious the mileage wasn't what it should be so I took it to my mechanic. I believe he changed the air filter (what a doh! moment that was) and suggested a fuel injector cleaner. He said he checked the spark plugs and they were fine. I ran the cleaner thru about 2 tank fulls ago and I'm still getting 15-17 mpg. I've got about 90Kmi

Do I need to take this to a dealer or are there some other DIY things I can try first?
I believe this car was originally from Denver. Would there be any adjustments needed to account for the difference in altitude? I know you used to have to do something back in the days of carburetors.

 

A few comments:

• A new air filter will not affect your fuel economy one iota.
• Fuel injector cleaner is another thing which is HIGHLY unlikely to affect a change one way or another.
• If you're typically driving in urban and/or heavy stop-and-go traffic, then your fuel economy isn't all that far out of line. That said, if you're getting 17mpg when on a long road trip with the cruise control set to ~72, then your mileage is decidedly low.
• Modern MAP and MAF controlled OBD-II engines automatically adjust for something we pilots call "Density Altitude" (an equation which sums up altitude, temperature, barometric pressure, and humidity); there are no changes necessary to take an East Coast car to Denver or vice-versa.
• While your car is still a bit young yet for Oxygen Sensors; it is not at all uncommon for folks to replace the Oxygen Sensors and see immediate improvements in fuel economy; even on cars that are otherwise running well and throwing no OBD codes. I say this as someone who abhors throwing parts at a problem; this is one exception.

Keep us posted on how you make out.

 

Going with the O2 sensor thoughts...
That sensor really measures the oxygen DIFFERENCE inside vs. outside. So if you have an exhaust leak blowing onto the outside of the sensor, that would throw off the measurement in the direction of a richer fuel mixture. 2007 is a bit new for leaky exhaust, but ???

 

Driving habits affect gas mileage greatly as others have mentioned. If you're taking short trips and the majority of engine running time is in cold cycle mode, then the gas mileage you're getting is definitely in line. If you're doing mostly highway driving then you're gas mileage would be considered low. If there is something wrong, it would usually throw a code. If there is a problem, I would start with cleaning the MAF sensor.

 

Correct me if I'm wrong, but I don't believe the OP's car has a MAF sensor; I'm pretty sure it's a MAP, and cleaning it typically causes more harm than good.

 

Around 2006/07 is when Honda started using MAF as a secondary sensor. I think the main "control scheme" is still MAP/RPM. Still, I took a quick look & 2007 EX V6 sedan auto.trans doesn't seem to have a MAF sensor anyway.

 

Thanks.

Can't say I've every heard of a manufacturer using primary MAP and secondary MAF; sounds kind of redundant (maybe that's the point).

 

I suspect the redundancy gives them a bit more accurate control as the newer EPA regs get tighter & tigher. Adding an MAF sensor was one of the few differences between LEV and ULEV engines back in the 6th-gen days.

 

I have nothing to add other than that the EPA lists a 2007 V6/auto Accord at:

• 18 City
• 21 Combined
• 26 Highway