98 Civic mpg dropped 30% and battery overweekend discharge

about couple two month ago, I had oil change, alligement, replaced tires, sparks plugs, air filter. about month ago, the mpg dropped from 32 to 22. and during holiday season, after a weekend, the battery comeptely discharged too. The battery problem happened last winter and I replaced the 20 months old battery with a new one, now it comes again, any thoughts?

Did your driving pattern change over the last month? A lot of time off at Christmas and no commuting . Cold weather alone would account for some mileage drop but not that much. Sticking brake caliper or sticking emergency brake / Before you spend money chasing the problem, Jack up the wheels and make sure they turn freely. For the dead battery get a free charging system check at autozone or advance auto parts before you spend time or money chasing a parasitic load.

Thank you, oldtimer for your advice. My drive pattern did not change, always home to work. I will have the wheels and battery checked. Thanks.

Although it shouldn’t cause the battery drain, you didn’t mention replacing the spark plug wires. How old are they?

I also wonder if you might have a sticking brake caliper, a sticking parking brake, or a dying clutch. Any of these can lead to decreased fuel economy.

Regarding the battery drain, I am no help with electrical problems. Perhaps it is time to get the alternator tested. Some auto parts stores will test it for free.

the sparks plug wires are about 3 years old, should they be replaced too?

I feel the sticky break caliper is a good point to start, since I feel the engineer is not as powerful as it was, espacialy there is any slope.

That sounds more like a slipping clutch than a brake problem. Does your car have an automatic transmission or a manual transmission?

oh, I forgot to mention, it is a automatic transmission. but the transmission fluid never been replaced, could this be a problem?

You want to be sure you have the charging system checked as oldtimer suggested rather than just the battery. They’re different things. The charging system consists primarily of the alternator, recharges the battery after starting, and keeps the battery charged as you drive.

The battery is the storage device. The charging system is what makes the electricity.

30% is a big drop.

Yes, you should get the spark plug wires changed too, as well as the rotor and distributor cap, and I’d also want to verify that all the cylinders are firing. This can be done quickly and simply in a number of ways, probably most easily with a spark tester.

You should change your fuel filter as well.

Yes, you should have your tranny serviced.

And, is the engine revving without pulling the car along at any time?

My final guess is that the drop in mileage is caused by simple ignition components long overdue a change, and perhaps even a clogged fuel filter.
My guess on the battery problem is that your alternator has lived its full life.

How are you measuring the mileage?

If I had known your 12 year old car still had the original transmission fluid in it, I would have never responded. No disrespect intended, but if your car is that neglected, it could be anything. For all we know you might need a new transmission. I drive a 98 Civic, and I am very fond of the car. Hearing how you have treated yours saddens me.