possibly a bad oxygen sensor?? please help

[eclipse0508]

I have been getting really bad gas mileage on my 95 eclipse gs. my car has the following upgrades....Iceman CAI, Greddy header w/downpipe, mozart system exhaust and NGK plugs and wires. Besides the bad gas mileage, my car seems to be running really poor, loss of power is noticable. I am only getting about 220 miles per tank. Also, every so often when I start my car, it will start okay, then almost instantly it will bog down and shut off. It has even died in the middle of me driving it. I believe it might be a bad oxygen sensor, but Im not getting any check engine light, so I cant get a scan done on it. Can anyone help me in how to test the o2 sensor? Any info on what else the problem could be, would be very useful.

thanks

also, i do not have any check engine light coming on.

 

[JayRolla]

You should beable to have it scaned still. Just because there is no CEL the ecu still may be throughing a code. They stay stored. I would have it scanned

 

[chrisfrye]

If you have a haynes manual(just for looks), it should tell you the proper voltage and how to check the oxygen sensor with a voltimeter. I only have the one for 1g. you can also pull it out and inspect it, see if it looks burnt up, if its bent, any of the holes are restricted.
When you say it died in the middle of you ridding it what happened with that? did you drop real low in rpms, come to a stop, punched it, switching gears... i dont know i cant say for sure but i havent heard of the oxygen sensor causing something like that. When an oygen sensor fails it goes into open loop mode in the ecu and uses a base set of fuel maps to give you the right amount of fuel, which would result and a less accurate a/f mixture.