well I am running rich all the sudden and getting poor gas mileage all the sudden I am only getting like 16-17mpg. I need help. for the most part my 1991 300zx n/a is stock I am running good fuel press. Is it a mas, 02 sen. Any toughts

 

could be O2 sensors, temp sensor, plugs, etc....quite a bit of things.

 

new plugs, and temp sen.

 

Could have a dirty air filter, dirty fuel filter, could need the throttle bodies cleaned, tires could be low on air.

Could be lots of things.

 

MAF???? throttle boddies yes.

 

It's not the MAS. A MAS won't cause poor mileage.

 

MAS my bad. hmm... is this like crazy rich? or just rich? as in a bit of smoke bad gas mileage. just curious

 

Any ECU codes?

 

Crazy rich? Is that a technical term? How would one determine if their car is just running rich, or running crazy rich?

 

Maybe CRAZY rich is liquid fuel coming out the exhaust pipes.

 

Oh shnit, a thread bagg'n on Sno..lol..hmm crazy rich?

 

It's probably a bad O2 sensor

 

haha. basically yeah its almost a liquid or distinct smell of pure gasoline straight out the tail pipes. compared to as where you said you noticed gas mileage suffering so you say its rich. it made sense in my head. haha. CC understood me.