Poor Gas Mileage

[mjh67]

Hello,
I have a 92 Metro, did a complete tune-up, and oil change, Just figured my mileage, and am only getting about 26 miles to the gallon...I am mechanically inclined, but this has me stumped....this car should be getting way better mileage than this correct? It has a new O2 sensor, but the car has failed Indiana emissions due to high hydrocarbons,(HC), the Standard is:0.80, the first time it failed was when the previous owner had it tested, it failed @ 3.23, I got the car, tuned it up, ect, as I stated, and it failed even worse @ 3.49 with fresh plugs, wires, ect, and synthetic oil. The car smells as if it's running rich, I pulled the plugs again after it failed this time, and #2 plug is blackish. I also checked the EGR, and it's functioning fine( did a vacum check) The other plugs look fine....can anyone steer my in the right direction....the car shows 91,856 miles on the clock, and I know it may be more, but the engine looks to be clean internally, from what I can see from the oil fill....dipstick comes out clean, and it doesn't seem to burn oil. I got the car with hopes to save on gas as I have a Chevy K-5 Blazer with a 5.7, and can't afford to feed it at the current gas prices, so I was a bit disappointed to see that this car is only getting 26. Any help is appreciated!!!!

[SeanMurphy]

I'm have a very similar problem, as detailed a couple posts down. I'd suggest getting a compression tester and checking to make sure the engine builds pressure and holds it. You should see 180psi per cylinder, and it shouldn't bleed pressure off very quickly, if at all.

Smelling of gas and a wet plug tells me you probably have a misfiring cylinder #2. Check the distributor cap to make sure that the post isn't cracked or worn. Heck, replace it anyway, it's cheap and you're already in for a penny, might as well be in for a pound.

Other than that, you could have a burnt valve in cylinder 2, or a bad ring, and the compression test would tell you either. If it doesn't build pressure on cylinder 2, try pouring a couple spoonfuls of oil down the cylinder, if it builds pressure after that, it's probably a worn ring, if it still doesn't, it's either a bad valve or a severely damaged ring.