A84Nate

My CEL cleared itself today, Yahoooooo!!!

A84Nate

Eversince my CEL cleared, I've been getting pretty crappy fuel economy. With the light on I would average 23-24 mpg mixed city/highway and that is calculated by hand. Now I will be lucky to get 20 mpg. I've not yet run the second can of BG 44-K through a tank of gas but I was wondering if this is normal.

jordonb

Well, I have a 1.8T, so I can't say what your mileage should be, but I don't think it should have dropped off.... Did you
change your brand/grade of fuel? Are you using ethanol blended gas? Is it possible you fouled your spark plugs?

A84Nate

I switched to Chevron 91 octane and I believe all of our filling stations in Utah have 10% ethanol fuel. I don't understand how I could have fouled my spark plugs and not have a misfire or rough idle.

jordonb

Shell v-power 91 octane contains no ethanol.
If even your plug gap is incorrect it could affect performance without throwing a code. Not saying this is a guaranteed problem, but if you had some bad gas, maybe the plugs got a little fouled. for that matter, have you changed your fuel filter? I just changed mine a few days ago.... Quick and easy (maybe 20 minutes or less).Also, how is the air filter? Also check the little screen where air passes into the airbox to be sure it is clean and free of debris. Also, keep in mind that at this time of year with colder weather and snow on the roads that fuel mileage will suffer a little. Also, if you recently changed tires it could affect mileage.
Do you happen to have a vag com? It is a great tool for helping to diagnose problems.

A84Nate

Thanks for the tip on the Shell V-Power but I'll have to search online for the nearest Shell station because we don't have many of those. I havn't changed any filters or my engine oil because I wanted to run a second can of BG 44-K through first to get things extra clean. My air filter is in good condition but I'm not sure about the other screen you mentioned. I did put a new set of tires on a few weeks ago and both my front and rear alignment done the same day. The all season tires I picked shouldn't be the culprit because they have a low rolling resistance. Today, after church, I noticed the smell of burning oil briefly while driving but everything else was normal. No smoke, warning lights, visible oil leakage, or odd smells coming from outside the car. May have been coming from the snow blower a man was using as I drove by.

jordonb

again, not sure about the 3.0 engine, as i have a 1.8T, but i had an occasional oil burning smell too. it went away when i changed the valve cover gasket. if it wouldn't have gone away, i would have thought cam seal.
not sure how any of this might relate to your mileage dropping though... still, like i said, perhaps it is due to the winter weather and roads?
when you do get around to changing your oil, perhaps it would be a good idea to pull your plugs and inspect them (or for peace of mind, just install a new set).... any time i buy a new car, i do a seafoam treatment, change the oil, all filters, plugs, flush the brake fluid, and give it a real good overall inspection just so i know where some of the maintenance is at.

Kid Talegas

Another burnt oils smell case here. had me very worried until it went away once i changed the cabin air filter(!?). i checked around the valve cover and rear main as a local indie turned me on to it as typical seeping paths but my 1.8T is clean there....


also another vote for the wintery driving conditions and blended fuels to be a cause for your MPG drop. i am averaging 20mpg city and 28-29 mpg highway driving (at 80 mph averagish)..

wheelmanbg

Where did you get this 44K? I want to try it.

Trey A4

Yeah, I might want to try it too. I have the same issue for one of my cats on my 8 yr old 3.0. I was a couple of thou over 80K, so no coverage. Unfortunately, my guess is that the code will come back some time in the next few mos. My light has gone off but it always come back. Fixing the cats under CA law is cost prohibitive, unfortunately. You may have the option of a cat bypass or a non-CA legal cat, either of which would cost much less than a replacement.