What do you make of this?

I'm at my witts end as far as MPG is concerned. My MPG has dropped from 18-19 to about 15-16. Now this tank seems to be even worse.

Recent maintenance:

-Iridium Plugs 8k miles ago
-Cleaned KN Filter
-Replaced Fuel filter 500 miles ago
-Constantly use Lucas injector cleaner
-Also used Gumont Regane this last fill up
-Tried cleaning MAF, However stripped a screw, so its hard to clean it.
-Seafoamed twice using vacuum line
-Been using Royal Purple synthetic for about 10k miles
-Changed Differential Fluid with Mobil 1 synthetic
-Also reset ECU

Now, today I noticed one more thing. Once I started the engine for about a minute and turned it off, I noticed a gasoline smell coming from the exhaust.

Could that be a bad O2 sensor? Or just winter gas?

 

I too thought of going to Denso Dual Grounds, however I hate to think I wasted so much money on Iridiums for nothing. Only 8k miles used.

I really do not think that Lucas Upper Cylinder Lubricant is all that bad. A lot of people use them and it works. I also use it all the time in my corolla, and it is just fine.

As far as the O2 is concerned, I thought that if it was bad I would get a check engine light?

 

Seafoam?

 

definitely sounds like an o2 sensor is heading out on ya. you will get a cel, but only when the sensor isnt functioning.

 

Forgot to mention that I seafoamed twice. LOL

Both times through the vacuum line.

 

Seafoam does work on everything

 

I really can't but I know a lot of people who swear by it. I am kind of a sucker like that. lol

 

Well since it is sounding like an O2 Sensor, has anyone had to replace theirs yet?

 

My truck has 53,000 miles. Does that seem a little soon for an o2 sensor?

Also where did you get your o2 sensor and how much was it?

 

replaced my bank 1 sensor 1(upstream) a few weeks back. not hard at all. the clip is the biggest bitch about it.

 

my truck only had right at 60k.

got my sensor from the stealership.....right about $215 or so.

rockauto.com has the alot cheaper.

 

Damn, that is quite a bit. However this bad gas mileage is driving me crazy. I suppose I should test the older one before I replace it.

Most likely, would the bad sensor be the upstream one?

 

thats the one that goes most often i believe.

 

The primary/upstream is the one that controls fuel mix, the secondary has nothing to do with fuel, it just makes sure the cat is working OK.

O2 sensors have a life span, they wear out like anything else. I replace mine based on mileage, around 80 to 100000 miles, but they can fail earlier

 

Just did mine at 110K and got it at RockAuto.com for a descent price.
its perty easy to do, its just that stupid little clip that a bitch to get to and up plug.

I will be checking my MPG's soon.

 

So should we be replacing the Bank2 sensor as well? the one for the cat.