7th gen accord fuel consumption woes

[ian silva]

Hi.. Hoping for help on getting this fixed.
I have an 05 accord, i4, Automatic. Just over 135,000 miles. MPG has been declining for the last few months. When I bought the car I was getting around 17.6MPG and now Currently at about 12MPG. Things I’ve done so far is listed below. No codes found, does not show a rich or lean code, STFT is between +7 to +10 at idle.
Changed front and rear o2 sensors with Denso (O2 and LAF sensor)
cleaned throttle body
Changed Map sensor
New air filter
New PCV Valve
new NGK spark plugs
Injectors cleaned
Engine oil is Castrol 5w20
transmission fluid changed with honda dw1, less than 3000 miles back
I run on 91 octane fuel (the lowest available where I live)
smoke tested for vacuum leaks multiple times, and a few were found, all fixed.
IAC valve rerouted and blocked off (as I thought it might be feeding excess air into the intake, bypassing the MAP sensor)
Tires are filled to 35PSI all around.
The average ambient temperature where I live is about 104 degrees Fahrenheit
Nothing I do seems to make it better, just progressively worse. The engine idles at around 800rpm, Runs smoothly, and has no hesitation, no jerking, or anything weird. No black smoke out of the exhaust, no water in oil or anything like that. Even checked to see if the fuel is leaking out, but didn’t find anything. please help… Any advice would be greatly appreciated.

Topic

[EricTheCarGuy]

If there was a performance issue the CEL would likely be on. If it’s not, the the type of fuel being used, driving habits, or ambient conditions are the most likely cause. The use of AC does effect fuel economy BTW.

Know that altering the engine, like blocking off the idle passage can effect fuel economy. The less you mess with it the better. Also, I highly recommend OE parts whenever possible.

You might also find this info helpful. http://ericthecarguy.com/faq/finding-and-fixing-the-causes-of-poor-mpg

Good hunting

[Author]

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