14 mpg - I need help!

[polskamafia mjl]

Well, still struggling to get 18 mpg even at highway.

New exhaust, from cat back
New plugs from Volvo
New air filter

What else can cause bad gas mileage? It used to be 28 mpg on the highways.

Thanks
Matt

This:

My slow decline in gas mileage was eventually traced to a bad O2 sensor. I was getting about 14/20 hwy. I never had any codes, but I had pretty much eliminated everything else. At 170,something miles, it was about time for a new one anyway. The one I pulled out was covered in a white crust, so it had probably needed to be replaced for some time.

Trace down ANYTHING else you can find though, first. Vacuum leaks, clean the MAF sensor, rule out leaking injectors, pre-cat exhaust leaks, a bad fuel pressure regulator, etc.

[Free2drive!]

Thought I'd give a bit of feedback and thanks to all who posted.

My mileage is back up to 28+ mpg, in fact I think at 55mph I'm getting low 30's.

The plastic hose that goes between the airbox and turbo had a split on the concertina. Only whe I pulled it and held it up to the light could I see it. It was gunged up with oil from the ptc nipple. Because it is an air leak after the maf sensor my u2 sensor was asking for more fuel.

Seems quieter and faster and smoother, me happy!

Thanks and now onto other issues.

Matt

[jblackburn]

That would do it! Congrats, that's much better than 14 mpg

[v70xc]

I too am getting bad mileage as listed in the past few fill ups.
16.660
13.921
15.889
17.437
Suggestions?
would vacuum tests give answers?
No codes "Thank God"

[EstVolvo]

Check your temp gauge - does it come up and stay up?

[Red-Arrow]

Always look for vacuum leaks when your getting bad fuel economy.

[v70xc]

EstVolvo: temp gauge gets to about 4 o'clock. I understand it should sit around 3 o'clock.

Red-Arrow: can you tell me how to test for vacuum leaks. I have no devices to test for this. Suggestions on how I can test without buying equipment that I will only use for one test...?

I have been hearing a lot about MAF and crack in plastic pipe going to turbo.
Could either of you tell me where to find the MAF? I have probably seen it a dozen times, but am not sure what it is ...

Thank you

[EstVolvo]

v70xc
Luckily previous owner took care of the vacuum-lines and such - so I can't help you here.
But I changed the thermostat after I noticed:
1.milky stuff under the oil cap
2.bad fuel economy
3.long time to warm up inside the car - first I thought why do they have such a weak heating in those cars ...
4.temp gauge going down on highway driving and up when idling in a parking lot.

After I changed the thermostat it gets warm much faster, there is no milky stuff under the oil cap, temp gauge goes up and stays at 3 o'clock, fuel mileage needs to be tested.

On turbo engines they have a thermostat that opens little earlier than in non turbo engines - so maybe temp gauge is supposed to be lower? Hopefully somebody with turbo engine can help us here.

It is easy and cheap to change the thermostat.

[v70xc]

EstVolvo: Thanks for the prompt reply.
Might you have pic as to where I can find the thermostat.....sounds like you are suggesting to change it..?

[matthew1]

4 o'clock means the engine is running cold. Get a new thermostat in there. DIY instructions.