I have been experiencing lower fuel mileage for a few months, now. The car used to get 29-31/34-38 mpg. Now, it only gets 27-29/30-33 mpg. I suspected the 80,000 mile catalytic converter (car has 181,000 miles), but the muffler shop told me they rarely go out and that the car would be running like ****. The car seems to be running just fine. The revs drop quickly between shifts, but I may be exagerating that in my head. He suggested a faulty sensor, but my CEL light is not on. I tried jumping the connector, anyhow, but it didn't flash any codes.

I have a replacement fuel filter, but can't seem to get the old one off. I plan to try it again, tonight. I recently changed the plugs, oil, oil filter, air filter, pcv valve, temperature sensor, clutch master and slave cylinders, and thermostat. I also just repaired the main relay and some faulty cooling fan wiring. I do know that the valves probably need adjusted, as the valve cover gasket and o-rings are leaking. However, it was doing that before the mileage started to drop. The clutch will sometime chatter on take-off until it heats up, but it does not slip.

Does anyone have any suggestions on the converter deal? Do they often last a long time, or is this muffler guy mistaken? It hasn't been my experience to see a muffler shop purposely turn down work. Would something like a faulty O2 sensor definitely set a code? I know that with my GN, a lazy O2 sensor could often go undetected by the computer.

TIA

 

The fuel filter is a very likely culprit. When I got my accord (used) it was partially clogged killing my gas mileage and acceleration. It is a royal bitch to change (got pissed off and took it to the dealer after like 3 hours of tinkering), however I'm told a crows foot with a long extension from underneath will crack it loose. Problem is you don't have enough room to turn a wrench and get a good grip on it.

Another good culprit would be one or both oxygen sensors. I'm not really sure on OBDII, but the ECU probably won't show a check engine light until they get really bad. They're made to fluctuate with temperature so technically any reading the ECU gets is within limits. There is a way to test them with a volt meter, however I don't have the numbers on me. If you need when I get home I can give them to you.

If it was an immediate loss in gas mileage I'd say the filter, if gradual probably a sensor thing.

 

o2 sensor is only good for 80K I would see about replacing that and do a tune up at the same time.

 

Car is routinely maintained and has a recent tune-up. I have not replaced the distributor cap, rotor, or coil.

I'll keep trying to get the fuel filter replaced. If that doesn't fix it, then I'll go with a new O2. The 94 Accords only have one, correct?

 

yes they have only 1