Fuel Economy Issues

joeliomartinijoeliomartini Band Wagon
in Engine & Drivetrain
Hi, I am new to owning a wagon, and to these forums.

I recently purchased a 91 rt4wd Manual Civic Wagon with 140,000 miles on it. It's been great so far, however it has been getting really spotty fuel mileage, even on the highway.

Yesterday it was getting anywhere between 21-25 mpg on all highway driving. So far I have done an oil change, changed spark plugs, and installed a new 02 sensor. I have also heard that installing a new ECT sensor is also helpful for this issue. Does anyone have any other suggestions?

The engine temp gauge always runs 20-30 degrees below the midpoint. Is this normal for a civ wagon? In every other car I have owned the engine temp gauge always goes to the exact midpoint on the gauge.

Also, there is a single 10 inch subwoofer in the back of the car pushing somewhere around 300 watts regularly I think. Would this have any real effect on gas mileage? It doesn't have a capacitor, but it also never dims the lights or seems to have much effect on the electrics system at all.

Any help on this issue would be greatly appreciated! Thanks

Comments

  • Eagle BeagleEagle Beagle familEE
    Hi new fuel economy first post'r ...

    any skills, pictures or other info ...

    maybe someone recognizes the car

    air, fuel filters tyre pressure sparks , etc ...

    shaving your head for better aerodynamics

    that kind of action

    :mrgreen:
  • SiWagonSiWagon Council Member
    Your MPG sounds about normal. :? EPA says 26MPG highway.Don't know which state you're in?Could be the state adds in alcohol during the winter.This could drop the MPG by 1O%.A trick you could try that I always wondered about is to run it on the highway in 2WD mode only.Probably not much improvement,but in 2WD mode you're NOT spinning a gear, the long 1/2 shaft & part of the VC.

    Other possiblities:
    1)Running a wider than normal size tire.This adds rolling resistance .
    2) Change the rear diff. oil.It's probably never been changed & may have THICKEN over time.
  • White&NerdyWhite&Nerdy Senior Wagonist
    Assuming you're in the U.S. (since I don't know about the rest of the world), it's winter, and winter blend gas does tend to lose a few mpg. Even my gf's CRX Si is only barely breaking 30 (it's easily exceeded 40 before). My RT4WD wagon is running 22-23. And my gf's Toyota Highlander might as well be a Hummer for the mileage it's getting. :shock:

    Good thought on the rear diff oil, though. I haven't changed mine since I got the car a year ago, and probably should.
  • skinnyskinny Senior Wagonist
    I get anywhere between 200-250 miles per tank. Im running a SOHC ZC that i run out to the red line often. It may not feel like it but our cars are about as heavy as a teg so our little motors have to make up with lower gearing and that can hurt your milage. tuning may bring out more but its not gonna be a whole lot.
  • fettcolsfettcols Wagonist
    When I first bought mine it got some weak mpg's. I discovered 80/90wt oil in the trans, just changing that with the honda tranny oil and my mileage went up about 4-5 per gallon.
  • SlammedtallboySlammedtallboy Wagonist
    Def noticed since I'm not driving my wagon on freeway all the time my milage has gone down. I prob get 25mpg out of my DOHC ZC
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