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Ask EricFromCT Your Own Question
EricFromCT, ASE Certified Technician
Category: Subaru
Satisfied Customers: 3810
Experience:  ASE Master certified L1, L2, Diesel Certified 16 years experience
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MPG fluctuate between fill ups. starts out low 19.2 mpg and

Customer Question

MPG fluctuate between fill ups. starts out low 19.2 mpg and gradually moves up to around 23 24 mpg by the of the end of the gas in tank . It use to hold constant at 23 -24 mpg. I have had a tune up. tires inflated. please explaine
JA: When did you last clean or replace your air filter? And are the oxygen sensors in good working order?
Customer: air flier recently replace, don't know about oxygen sensors.
JA: What is the model/year of your Subaru?
Customer: 2010 forester
JA: Are you fixing your Forester yourself? What have you tried so far?
Customer: NO a mechanic, plugs and wires. air filter. B/4 that I ran a higher obtain and ran sea foam through the tank got up to almost 27 mpg only lasted a short time
JA: Anything else you want the mechanic to know before I connect you?
Customer: No I don't think so
Submitted: 6 months ago.
Category: Subaru
Expert:  EricFromCT replied 6 months ago.

Hi. How long have you noticed this happening?

Customer: replied 6 months ago.
several months
Expert:  EricFromCT replied 6 months ago.

Ok. Has the weather changed as in getting colder outside where you live? Also do you have a remote start for the vehicle?

Customer: replied 6 months ago.
weather ha changed but its been going this through out the summer. I don't think that weather is causing the fuel problem. No I do not have a remote
Expert:  EricFromCT replied 6 months ago.

The effect of cold weather on the vehicle can decrease the fuel mileage. Colder air is much denser and requires more fuel. Also in cold weather usually the car is idled more, from perhaps warming it up before driving it.

Expert:  EricFromCT replied 6 months ago.

The computer uses the calculation of how much fuel in the tank has been used, how far you've travelled on the tank, and the amount of accelerator pedal and idle time used to get the average mpg

Expert:  EricFromCT replied 6 months ago.

Thank you for using Just Answer and please take a moment to rate my assistance with your question. And, as always, after rating the question will remain open for any follow-ups you may have. Thank you.

Expert:  EricFromCT replied 6 months ago.

Please let me know if you have any more questions on this. If you could also please take a moment to rate my assistance, that would be appreciated. Thank you.