Started my car up the other night after work and reved it a few times... a friend noticed that my car "smells like a lawnmower." IE, it smells like a rich blend of gasoline and oil. Checked the oil every night and the level isn't really changing, but the car does seem to possibly be burning more fuel than usual. I haven't noticed any performance changes, other than it does seem to backfire a bit more than usual. Car also seems to idle slightly lower than usual (~500rpm vs. usual 700rpm)

Car is a stock '90 GXL with ~39k on rebuild. I'm pretty sure I need a new o2 sensor (I have the sensor but not a wrench that will both fit on it AND have room next to the wheel well to turn :P) anyway, was just wondering if this could also be an o2 sensor problem.

 

check your TPS adjustment and water temp sensor for ECU.... O2 will not have affect on this, it works pretty much only when u are cruising.....
bad or unplugged water temp sensor will make your overall mixtures richer (safe mode)
TPS out of adjustment will have affects on mixtures as well...
checking error codes should help as well

 

where is the water temp sensor located

 

Bottom of the radiator. If your looking from the front into the engine bay it is on the bottom right I believe.

 

actually i beleive the water temp sensor is on the water pump itself. heres a pic.

 

Take off the alternator, its that much easier to access....
if you are looking straight down at the alt from the front of the car it will be just down and to the left with a green (I tink) plug on it...
Its along the water pump filler neck. .........Hidden in the pic above