i bought a 99 accord I4 sedan with ~130k miles, this spring. it had no maintenance record.

i was getting 27-30 mpg, but soon realized it was consuming quite a bit of oil. nearly a quart per tank of gas

then (around august) i got a ecu warning that came up as a misfire on one of the cylinders. not knowing anything about engines, i took it to a local shop and they put in new spark plugs, but couldn't get the misfire to replicate, so they didn't do anything else.

since then i have had a few more misfires (but not very often), but directly after they did work on it my gas mileage dropped to the 20-23 mpg range it has stayed in that range for the last few months.

also, at high rpm's i get some dark smoke out of the tailpipe.

recently i have changed the air filter, pcv valve, and installed the small diy catch can as described in the sticky (which fills about halfway every tank of gas).

since these changes (a week or two) i have not gotten any misfires, and seem to have lass dark smoke (at high rpm's), but my gas mileage is still in the lower 20's and oil consumptions remains the same.

since i bought it i've gotten the oil changed every 3000 miles with 5w-30 (non-synthetic).

it should also be mentioned that i'm in college and work limited hours, so i do not have any extra income anything over a couple hundred dollars is totally out of the question.

any suggestions on what i should try next?

 

Sounds like you have an oil burner. Replacing the oil fouled plugs reduced the misfire episodes. As for the drop in MPG...Did the shop use the correct NGK plugs as replacements? Are the plug boots firmly seated onto the plugs. Are the plug wires in good condition (not soaked in oil or cracked)?

Colder temps will reduce fuel mileage, but not as severe as you indicate.

 

Drop in mileage is a strange one; you're talking like at least a 20% drop in mileage. A Honda dealer might be able to help you out, but it wouldn't be cheap. One comment on the oil usage though; if you're really using a quart per tank of gas (or so), you're wasting your money having it changed. You're using it way faster than it would take for the oil get dirty or degrade.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2005S2000 &raquo;</TD></TR><TR><TD CLASS="quote">Drop in mileage is a strange one; you're talking like at least a 20% drop in mileage. A Honda dealer might be able to help you out, but it wouldn't be cheap. One comment on the oil usage though; if you're really using a quart per tank of gas (or so), you're wasting your money having it changed. You're using it way faster than it would take for the oil get dirty or degrade. </TD></TR></TABLE>

yeah, i'm stumped and don't have money to take it to the dealer and tell them to make all my problems go away

i really do use that much oil, though. i'd say about 500 miles and it's off the dipstick