Really Bad Gas Milage?
 

So, last time I got gas I got 14.2mpg. I decided to give it another go just to make sure. I got gas tonight: 12.6mpg. I'm not quite sure to go about diagnosing this one... I don't drive too crazy; I'm assertive:), but not enough to warrant that bad of gas milage. I resealed the engine, replaced the water pump, timing belt and pulleys, cylinder heads, 2 of the camshafts, knock sensors, filters.... So I think the engine is okay. I replaced the transmission so that should be okay... What else could cause this bad of gas milage? Thanks

Re: Really Bad Gas Milage?
 

o2 sensors?

Re: Really Bad Gas Milage?
 

Is there a way to check if they're bad or do you just replace them and hope for the best?

Re: Really Bad Gas Milage?
 

All I know is that if your going to get them replaced, get the good ones... not the cheap ****. (aka universal) If your willing to put in money in everything else, no need to sacrifice elsewhere or where it helps/counts.

Re: Really Bad Gas Milage?
 

Haha, yeah. I'm not about to go cheap after all I've put into this car. I just wanted to know if there is some way to check them before I replace them. And if I do replace them is OEM ($213.28 @subaruparts.com) the way to go or some other brand?

Re: Really Bad Gas Milage?
 

Check codes and see if anything is stored in memory.

Re: Really Bad Gas Milage?
 

I used the $25 ones on ebay which lasted 1 week. Then bought some Denso universals for $60 a piece and they've been great for almost a year now.

Re: Really Bad Gas Milage?
 

Before dropping the cash on the 02s just yet, theres other things that can hurt your mileage. Id first try some good quality injector cleaner thru the system. A binding brake or low pressure in the tires would be a factor. Mine always gets great mileage on the highway, almost 30, but in the city with a cold start every morning im lucky to get what you are. Just a thought, oh and a vacuum leak can also kill mileage, id do a quick once over of your intake tube and see if any of the 600 hoses that go to it were forgotten, it happens (I know).

Re: Really Bad Gas Milage?
 

Alright, now I tried to pull the codes for my engine and the check engine light does not come on. I fact I have never see it... It doesn't come on when all the lights turn on when you first start the car. I think it's supposed to be to the left of the power light. The bulb must be burned out or something...

I checked intake hoses and they all seem to be in the right place. I also have another problem that might be causing problems, but I'm going to post that in another thread so someone with the same problem will be able to find the answer...

So it sounds like OEM O2 sensors are not necessary, so I'll go to napa and get some there if this other problem isn't the culprit...