bad gas mileage?

2000 chevy cavalier, 2.2L engine w/ 103,000miles. I rencently replaced the plugs and wires because one of the wires was so bad it was arching from the ignition coil to some point on the plug wire. B/f replacing the plugs/wires, the car was starting hard( ie seemed to have to turn over much more than was normal). This has not improved since I replaced the plugs/wires. I have to turn it over for a few seconds, then turn it over again for it to start...it seems to be related to it needing the fuel pump to run twice b/f it starts?

Gas mileage before this fix seemed to be slowly declining, and just afterwards seemed fine. Now it seems to be getting worse. At 1/2 tank, it was typical to get 180-200+ miles. Now at 1/2 tank, I am at 130miles. The check engine light is on, and has been for about 3 oil changes...I have ignored this because the person that changed my oil said the light was related to the catalytic converted being full/used up. In the winter, I use isopropyl alcohol, and have run ~4 fuel injector treatments in the last 1.5yrs.

Is there something characteristic of cavy's that shows a steady decline in gas mileage? Any ideas?


Thanks

Do you have a WAI or CAI?

warm/cold air intake..? These are both upgrades, right? It has whatever is stock...

thanks for your help

Ok. I had the same problem in a way. I have a WAI and I didn't have my IAT sensor plugged in right. Driving habbits, have they changed? Regualr oil changes? I'm don't know too much on why this could be happening. Properly inflated tires also.

When's the last time you had your fuel filter changed? It should be changed every 50,000km (30,000 mi). If it is plugged it will cause poor fuel mileage and hard start up. If you have to cycle your key twice for it to start right away, the fuel filter is more than likely the problem.