I have noticed that, lately, my MPG has been hovering around 19.5 when normally its around 22.5. then one day, the service engine soon light came on. I went to the local shucks and asked them to help me figure out what the problem was. the person said it was running lean, and told me that he went ahead and turned off the light. I dont know what he means by turning off the light, but he also said that its no big deal unless it comes on again so im assuming he just reset it. the light hasnt come on again, but my mpg is still bad. i calculated it and figured that im wasting 2 gallons per tank on normal driving.

i would just like to know how i can fix this because i took it to the dealer and they told me they cant do anything unless the light is on.

basically if the guy at shucks reset it and its still running lean, how long until the car figures out its running lean and turns the light on?

 

Has your car ever been tuned at all? Because the stock ecu makes it run very rich. So if its stock I don't see how it could be lean.

 

if the problem is still going on the light will set after the 2nd trouble cylce

 

Did you ever get this figured out?

 

nope gas mileage still sucks and light still hasnt come on.

 

Do u have an exhaust on the car? If so could be the o2 sensor. It would cause it to run rich though. If your car is running lean I don't see how gas mileage would decrease. Seems like it would actually increase.

 

an exhaust leans out the air/fuel ration, not richen

 

Replace the plugs, o2, and get a tune.

 

Fully aware that an exhaust getting more air out of an engine with the smae amount of air and fuel as stock going in will lean out the air to fuel ratio. My point was if the o2 sensor needed replacing it would be running rich cause the ecu will do that when the o2 sensor goes out. My other point was what he is saying is not making sense. He says his car is running lean. If it is running leaner than it should be how would gas mileage decrease. Shouldn it increase? My gas mileage is really sucking right now cause its running super rich due to an o2 sensor going out.

 

thats what i thought too, but the guy at schucks said that because the car isnt running optimally, its wasting gas even though its running lean. kinda made sense when he explained it

 

You need a tune that's what my evo needed