i have a 2003 accord 2.3 ex 5 speed manual w/120k miles on it. owned it since new. i use to get 30-33 mpg and recently after some work done, i'm only getting best 29 on highway cruise control at 75 mph for the whole tank. here's what i did 2 months ago before the loss of mpg's; and all of this was done in 3 weeks time.

1. short ram intake (self) aem
2. changed spark plugs and o2 sensor (self)
3. changed front shafts (dealer)
4. valve adjustment (dealer) they some how con me into it...
5. new tires (nexen 225/45/17) old tires (continental same size)

i don't drive any harder then i use to and i've been taking it easier since i noticed the mpg loss... i even had the throttle body cleaned. and nothing. i should've listen to my dad... if it ain't broken; don't fix it!! any advice???

thanks!!

 

Were the plugs and O2 sensor OEM parts?

Make sure that the tire air pressure is correct. Also, check that the brake pads aren't dragging.

 

Did you Check the gap on plugs before you put them in?

Even though when you buy alot of sparkplugs anymore they say they are gapped from the factory its still a good idea to double check the spark plug gap before you install them to make sure they are correct

 

the plugs (expensive) and o2 sensor (very expensive) i got from honda... the gap was correct when i put them in; and i just double checked tonight and they are still correct.

tire pressure, i'm over inflated already... i always like to run high, it's at 44-46 lbs. the wheels are rolling fine, on my last oil change when my car was jacked up, i turned all 4 wheels and there was no problem. my buddy has a car lift and that's where i change my oil.

anymore ideas??

thanks again!!

 

What was the reason you changed the O2 sensor?

 

You probably just have a heavier foot after installing the intake, I know I did

 

the reason for the o2 change was becuase the check engine light came on, i had it checked and turned off, after a mile from the shop it came back on with the same error message. bank 1 sensor 1... so i changed it and turned off the light and it stayed off ever since.

lead foot... for the first few hundred miles... oh yeah baby... but then after i noticed the horrible gas milage, i drove like grandpa... and it's still bad... so now i'm here. who else to ask besides experts like y'all!!

hope someone will help shed some light soon.

thanks!!

 

Your tire size improves apparent (not real) gas mileage (compared to stock) by about 3% (1 mpg), but would not account for a reduction in mpg w/ same tire size, unless new tire is an all-season compared to highway travel tire. Any significant road noise? That noise is wasted energy (reduced mileage) compared to standard.

I would remove the CAI and replace stock components. It does nothing except make a lot of noise and could be reason for reduced fuel efficiency.

Check PCV valve and hose. Check wheels for easy turning.

good luck

 

More air leads to more fuel. If i was you, I would check you fuel to air ratio.

 

you may want to have your exhaust checked out usually the catalytic converter needs replaced bout the same time as the O2 sensor. (alot of time a plugged "cat" and/or Muffler is the reason your O2 sensor goes bad)
I would suggest haveing exhaust checked out and if you find the muffler needs replaced i would have your buddy with lift do it.

The best way i have found to check cat is to remove the muffler and fire up the car if the exhaust doesn't sound like a stock car at the race track pretty safe bet the "cat" needs replaced