Hello everyone! I've read numerous threads on this site throughout the years and got a lot of helpful info but now it's time to post for once. I'm stumped with this one and I'm about to sell this thing but I am curious as to why it's getting crappy mpg.

I am by no means a mechanic but I have learned so much messing around on this car

I've got an 05 SXT, automatic, standard 4 cylinder engine that's been in the family since my sister purchased it brand new in 05.

At the end of last year the head gasket burnt out between cylinders 3 & 4. We took it to a mechanic who replaced the gasket. He also did the timing belt, water pump, a pulley that came in a kit with the belt and pump, new oil, antifreeze, oil filter.

After I got it back I noticed after a couple fill-ups it wasn't getting good gas mileage at all. I've estimated over the months it averages about 15 mpg. Seems pretty weak to me.

Here's everything I've done to it for various reasons that I can remember. I've replaced the PCV Valve, Spark Plugs, Wires, Coil Pack, Camshaft Sensor, Air filter, I've cleaned intake manifold, we replaced a fuel injector and all the gaskets on all fuel injectors.

There's no error codes or lights on, it runs good, sounds good. I don't drive it very much due to the poor mpg.

The only thing I wonder about and I haven't replaced is the catalytic converter or the sensors with it but I'm getting tired of throwing money at it. I would like to know what the heck's going on before I sell it. It's still a real nice car!

Thank you!

-Dean

 

-You could try the o2 sensor. When it goes bad it affects the mileage.

L8R,
Matt

 

Car is aligned? Tires are properly inflated? The catalytic converter only needs to be replaced when it is bad (it will glow bright red from being clogged up). The O2 sensors could be on their way out. Also, winter blend gasoline is being used right now, and that usually reduces MPG a bit. Have you ever calculated the MPG, or just guesstimated?

I'd hate for it to be the case, but the timing could be off too from the timing belt change if you are sure the big drop in MPG was after work was done.

 

Thanks BassMan!

Darthroush, Yes car is aligned, tires are properly inflated. Thanks for the tip on the converter, I put my hand at the end of the exhaust pipe and it seemed to be blowing exhaust out pretty good. Doesn't glow red either. I know it's all try this and see what happens but I hate to change the sensors for nothing and spend the extra money. There's no engine codes being thrown. It has been getting bad mileage since I started driving it after the work was done. I took ownership after the work was completed. My dad owned it prior to that but we never calculated mpg. He never complained about it but knowing him he never cared. He'd fill it up when he needed to and go on. I have been actually calculating mileage though. It has been getting approx 15 mpg since the work was done roughly back in January 2013.

We did check the timing belt and it's right on the correct marks. My step-dad helped me check it out (he's pretty knowledgeable on mechanic related stuff)

Thanks for the help!