2009 Accord V6 terrible MPG

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Originally Posted by krismoriah72

I think an italian tuneup and a highway test thereafter on mpg would yield much better results.

+1 for Italian tuneup.

I think a fresh full tank of ethanol free premium too might be a little treat for the fuel system. What about spark plugs? Original?
 
Originally Posted by IronMaidenRules
I think a fresh full tank of ethanol free premium too might be a little treat for the fuel system.What about spark plugs? Original?
Ethanol is a great solvent. Gasoline without ethanol, less so. You have it backwards. Besides, he is already putting in Techron with PEA. ..... Spark plugs are a good suggestion, as some fouling may be there, running it just rich enough but not too rich to get misfiring yet, or enough to set off the O2 sensor rich alarms.
 
Originally Posted by paoester
Originally Posted by IronMaidenRules
I think a fresh full tank of ethanol free premium too might be a little treat for the fuel system.What about spark plugs? Original?
Ethanol is a great solvent. Gasoline without ethanol, less so. You have it backwards. Besides, he is already putting in Techron with PEA. ..... Spark plugs are a good suggestion, as some fouling may be there, running it just rich enough but not too rich to get misfiring yet, or enough to set off the O2 sensor rich alarms.

Huh? Ethanol that sits is NOT a great solvent. It sounds like the car has always been driven VERY few miles and gas sits in the tank for a long time. This is bad. Regardless of what fuel used, it definitely needs to be driven more.
 
Run two bottles of Redline SL-1 back to back........
That should clean up your low mileage Accord nicely.
 
Originally Posted by JEL01
Nope you read that right, 29k. I got it a few months ago from a relative who rarely drove it, but it had been well cared for and perfectly fine until a couple months back. ...
Was your weather warmer a couple of months back?
 
Originally Posted by supton
Have you taken it out for a nice hour long plus highway drive? Maybe it does great out on the open road, which would indicate no problem.

Was going to suggest thing as well.... Find a gas station next to an interstate highway exit, fill up the tank until it shuts off, and note the current mileage. Go for a ~30 mile or longer drive, get off the interstate, and fill up, at a station right next to the interstate, until it clicks off again. Note the mileage, do the math, etc.

As already mentioned, 17 mpg ain't terrible for a V6 Accord. EPA estimates are 19 mpg. You're 10% under but that could be non-fuel-efficient tires (yes, that's a thing), worst-case "city" driving, etc.
 
Try running a bottle of a complete fuel system cleaner with PEA. Use according to instructions. They are all similar so get the cheapest which is usually one of the Gumouts.
 
Originally Posted by JohnnyJohnson
Sounds to me like your Honda is getting about average MPG

https://www.edmunds.com/honda/accord/2009/mpg/

Seems low to me. I get 18-19 with mixed driving in a V8 Mustang. I'd expect a Honda with 2 less cylinders that's 7 years newer to do better.

I'm going to guess this has a lot to do with the short-tripping though. The weather has probably gotten colder since "a few months ago" when OP says things were normal, and short-tripping a cold engine in cold weather is not good for MPG. Could also be an O2 sensor going bad, they do funny things sometimes. I replaced one in my wife's old Cavalier (which was throwing a code, but did not effect MPG) with a discount-brand one from Rock Auto that did not set a code, but dropped MPG by 5. Replaced with an OEM ACDelco sensor and had no code and MPG went back to normal.
 
Thanks BITOG, it has gotten colder but I'm still expecting better MPGs, especially since it's been mild so far (mid 50s to low 60s for the most part) my old '05 that I no longer have with the exact same conditions and 150k more miles averaged 22-23, the CLK in my sig is right around 20-21, as is the RX350, the only one that does about what the '09 Accord does is the Tundra 4x4 pushing 200k. I think I'll give it a good Italian tune up and see what happens.

As far as calculating, the old tried and true hand calculated method, and interestingly enough it lines up very closely with what the onboard computer reads.

My aunt drove the car prior to me getting it and pretty much puttered around town, so I may pull the plugs and replace them even though they're supposed to be good for 100k, or at least see how they look.
 
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Just for a point of reference, my 08 TL which is a 3.5L J Series (Non-VCM), is getting right about 19-20 MPG driving back and forth to work at the moment. This is a 12 mile drive with some slow county roads, followed by about 6 miles of 65mph cruise, and then 4 miles of stop and go in town.

On the highway with cruise set at 75-80 it will hit 26-28, but unless we're taking a trip I never see that.

Also, if I get in the mood to drive it harder it will dip down into the 17-18's.

Generally, I'll finish a tank of fuel with a 19-21mpg overall average according to the dash, which has been fairly accurate the times I've done the calculations by hand.

The wife is driving the 03 Accord at the moment, but I know it is actually getting similar mileage, at 220+ k miles its time for it to get new AF sensors as I think they're getting a bit lazy.
 
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This is what I usually get in '08 V6 with around 79K/miles with deactivated VCM in mixed driving with 5W-30 or 0W-40 oil -- ~19MPG around town during winter months in NY, it can get as low as ~15MPG, and the best I got in it is around 28MPG.
 
I just found a picture of my information cluster I took several years back from a trip with the family in the TL.

Avg MPG: 26
Avg MPH: 80
Distance: 136(miles)
Time: 1:38

REALLY long and boring stretch of highway on that particular part of the trip. And that was loaded with 3 people and a trunk full of luggage running the AC in the dead heat of the afternoon during the summer.
 
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