benh

Hey Gang !
I have been chasing a fuel mileage issue for approx a year now ! Tryed A bunch of suggestions from this site and others And finally nailed it this week!
First off the 2.4 has 245000 kms it gradually lost mileage over the last year went from a consistent 500 kms per 50 liter tank full down to 425 per 50 litre tank full slowly over the last year !
Things I went thru to get to this point included changing plugs / air filter / o2 sensor/ checked the CAT .ect: After having it checked at the dealer with a clean bill of health I had the compression checked And had found
2 - 3 cyl lower on compression 120 than the the other two 150 I assumed after a wet test I had a stuck ring issue !
The Fix Seafoam in this order
Remove plugs turn the engine to start of compression stroke on each cyl An pour in the cyl approx an ounce of Seafoam with the spark plug re installed turn the engine over BY HAND using the p/s nut past TDC this helps force the seafoam Past the rings! repeated this on the rest of the cyls.
Next turn the engine till all the cyls are halfway up the bores and repeat the pour in instruction this time leaving it soak overnight, Next day with spark plugs removed crank the engine for several revs and reassemble and drive for a couple of days then retest your compression In my case here my compression came up to even + - couple of pounds ! the mileage is now back to where it was when I got the car 50 litre per 500 KMs
Thought I would post this in hopes it will help others with similar issues! Worth a try in my mind!

Just something to try if your chasing a mysterious fuel mileage issue with no codes or anything else to go on!