SBT Posted January 29, 2006 Share Posted January 29, 2006 Mango, you might want them to check/replace your O2 sensors. My front 02 sensor was failing and finally threw a CEL, on my last tank before they finally got it replaced (they tried replacing the rear 02 first, which did nothing) I also got terrible milage, like 13-14 mpg...usually even if I'm driving like a maniac I get 17 and normal is 19.5. You should be throwing a CEL if that's the case, but I think the conditions to cause that are pretty extreme and maybe you're still on the border. When I finally did throw the CEL, it was P-2097, "Emissions - post cat fuel too rich" or something like that and the 02 sensor was the culprit...they fail all the time on these cars so I would definitely ask if they'd try replacing them both. Definitely would suggest this as this is a typical culprit on every long-term Subaru I've owned. And if it has failed or is failing, you'll be running rich no matter how easy you drive it. Staying below 3K rpms generally keeps you out of boost when the fuel loop cutover to rich activates. But, it sounds like you're doing that and the car is running normally (at least subjectively normal), so I would definitely check out the O2 sensors as soon as practical. SBT - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
team23jordan Posted January 29, 2006 Share Posted January 29, 2006 i get about average of 19-22 all the time if i step on it, i get about 19 if i don't step on it, 22 Perrin BIG maf intake Perrin Turbo Inlet HKS SSQV BOV Megan Racing header with UP (ceramic coated) HKS DP (WRX) DMH E-cutout Custom 3" catback UTEC Link to comment Share on other sites More sharing options...
KA81 Posted January 29, 2006 Share Posted January 29, 2006 could try manually checking your gas milage/16.9 and see if you get the same numbers Link to comment Share on other sites More sharing options...
Brady Posted January 29, 2006 Share Posted January 29, 2006 have you tried resetting your ECU to see if it has any effect? Link to comment Share on other sites More sharing options...
MangoGT Posted January 29, 2006 Author Share Posted January 29, 2006 Brady, are you suggesting a dealer reflash or just running the car for >20 minutes on the highway? Link to comment Share on other sites More sharing options...
Brady Posted January 29, 2006 Share Posted January 29, 2006 I'm suggesting disconnecting the battery, applying the brake until the brake light is out and then reconnecting the battery. This will reset your ECU to the original factory base map. If you see an immediate improvement, your ECU had learned some bad behavior. If it's still really low right away, something mechanical/electronic is bad (bad sensor or whatever). If it starts off significantly higher and after 2 - 3 weeks tapers off, you either might have a problem (sensor) or it could be driving style/conditions (traffic). Try it ... nothing to lose and you can't do any harm. Link to comment Share on other sites More sharing options...
MangoGT Posted January 29, 2006 Author Share Posted January 29, 2006 Sounds like a plan. Thanks for the info. Link to comment Share on other sites More sharing options...
jlce88 Posted January 29, 2006 Share Posted January 29, 2006 Just wondering if you're driving it in sport mode all the time. that has a big effect on my mpg. Link to comment Share on other sites More sharing options...
gt_ltd Posted January 29, 2006 Share Posted January 29, 2006 I'm taking it to the dealer again on Monday. why not try a different dealer this time? This Space For Rent Link to comment Share on other sites More sharing options...
ilh Posted January 29, 2006 Share Posted January 29, 2006 (NYsFinest, are you resetting the trip computer (A or B)? If not, you'll just have a very long-term average that won't really budge.) My hour commute can be pretty horrible here in the Boston area. Even in the worst stop and go, summer with A/C on, my average was never worse than 20mpg. I've got about 8 miles of 75mph, but the rest can be pretty bad bumper-to-bumper. If traffic is better than average, I can generally get closer to 22mph on average. This includes "opening it up" a couple times each way, not beyond the speed limit of course. I think something must be wrong to get 12-14mpg if you aren't going full boost at every light. BTW, my car had an inoperative O2 sensor due to a bent ECU pin. I had no CEL and the ECU wasn't indicating any codes. They only found out about it by logging while driving and noticing the air/fuel reading was stuck at a constant value. I was amazed I drove like this for 5000-9000 miles without any kind of indication. Link to comment Share on other sites More sharing options...
voyetra8 Posted January 29, 2006 Share Posted January 29, 2006 Just to add more "data" to the thread: I currently get: 22.2 = Highway, 80mph cruise 25.5 = Highway, 75mph cruise 12.0(!) = City, Boston I think I am going to do some logging today, just to satisfy my curiosity. Link to comment Share on other sites More sharing options...
voyetra8 Posted January 29, 2006 Share Posted January 29, 2006 BTW, my car had an inoperative O2 sensor due to a bent ECU pin. I had no CEL and the ECU wasn't indicating any codes. They only found out about it by logging while driving and noticing the air/fuel reading was stuck at a constant value. I was amazed I drove like this for 5000-9000 miles without any kind of indication. What were your symptoms prior to the diagnosis? Link to comment Share on other sites More sharing options...
Windex Posted January 29, 2006 Share Posted January 29, 2006 I'm getting a steady 23mpg, but I'm mostly highway... How are you ascertaining your milage? are you going by the trip computer (I hope not)... If you are filling up the tank and calculating by number of miles driven, how many times have you done this? (it is the only accurate way to check fuel mileage) post some numbers. As well, the dealer won't be able to help much if you don't have some definitive numbers to demonstrate the poor milage... I have had to deal with a few poor mileage customers in my time, and nearly half of them were due to incorrect calculations...not saying this is the case, just a possibility, as your calc. method is not stated. As above, city trips, cold temperatures and winter grade gas all do a number on fuel mileage. Link to comment Share on other sites More sharing options...
Scooter Posted January 29, 2006 Share Posted January 29, 2006 I've been pretty annoyed with my mileage the last couple of months, too. I got 14.8 on one tank in mild city driving, and just returned from a 500 mile freeway roadtrip: cruise at 78mph the whole way and the trip computer registered 18.5mph. Turbo or no, that seems ridiculous to me for a 4-cylinder engine. Might be winter gas, but I think I'll try out some of these suggestions myself. Seek first to understand, then to be understood. In other words: SEARCH before you post! Link to comment Share on other sites More sharing options...
Windex Posted January 29, 2006 Share Posted January 29, 2006 Heh.. forgot one thing. My car doesn't seem to have a 75mph sweet spot. As expected, the faster I go, the worse the mileage. Going by the instant fuel economy from the trip computer, and by a couple of tanks where I stayed at 60mph (100kph) I got better milage (25-26mpg) at lower speeds than I did at 75 (I tend to cruise at 75-80). Not unexpected, and wind resistance is proportional to the square of your speed (wind resistance almost doubles from 55mph to 75mph:( ) Still searching for that elusive sweet spot... Link to comment Share on other sites More sharing options...
Windex Posted January 29, 2006 Share Posted January 29, 2006 I think most people are using the trip computer, which can be the problem. as I mentioned earlier, the aVG it computes can be different when doing city vs. highway, and therefore not so accurate. I would agree with Windex, that the best way would be to manually compute it by seeing how long it takes to need a refill. I actually got a reading from the teip computer that was only .2mpg off (optimistic again) for the last tank. most of the time it is 2-3mpg off. Link to comment Share on other sites More sharing options...
SBT Posted January 29, 2006 Share Posted January 29, 2006 ...most of the time it is 2-3mpg off. Higher or lower that your computed "actual" mpg? - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
dark_rex Posted January 29, 2006 Share Posted January 29, 2006 12 is low. i get around 300 miles a tank and i do 50/50 hwy/city Link to comment Share on other sites More sharing options...
NYsFinest Posted January 29, 2006 Share Posted January 29, 2006 How do I reset it so my avg starts from zero? Link to comment Share on other sites More sharing options...
ChruiSSer Posted January 29, 2006 Share Posted January 29, 2006 Select your avg. MPG and then hold down that little black cylindrical trip reset for the trip odometer on the guage cluster. You'll see an A or B next to your avg. mpg and then once you reset it, it will go blank. That will reset it for you. On a side note, I'm running the STi turbo with no cats and I was getting 28.5 avg. today. Normally I avg about 22.8 with a 50/50 mix of city and highway driving. Link to comment Share on other sites More sharing options...
NYsFinest Posted January 29, 2006 Share Posted January 29, 2006 It wont also reset my odometer, will it? Link to comment Share on other sites More sharing options...
Brady Posted January 29, 2006 Share Posted January 29, 2006 It will reset your trip odometer only (whichever one it's set on [A or B] at the time you press and hold the button). You cannot just reset your entire odometer. Link to comment Share on other sites More sharing options...
MangoGT Posted January 29, 2006 Author Share Posted January 29, 2006 I don't stay in Sport mode all the time, I barely use it at all. I've been running my tanks well into the fuel warning light just to see how many miles I can get per tank and my last tank was just below 200. On the current tank I'm over 1/2 of the way through it and I'm around 126 miles. On average, I've been getting 200-220 miles per tank. How big is the Legacy's fuel tank? I've never been able to put more than 15 gallons in it and I've driven it far past the "30 miles left" mark on the trip computer. So if I put 15.008 gallons in the tank (my last fill-up) and I reach 216 miles (current miles on the tank = 126, estimated until empty = 90 miles), that means that I'm averaging 14.4 mpg. The avg mpg according to the car is 13.2 mpg right now. Link to comment Share on other sites More sharing options...
hondas123 Posted January 29, 2006 Share Posted January 29, 2006 I would call SOA or bring it to another dealership. IMO you should be getting significanly better mpg. I do mostly short distance/city driving and avg. 22.9. I don't have a lead foot, but enjoy some spirited launches. - The Mortgage Man Link to comment Share on other sites More sharing options...
MangoGT Posted January 29, 2006 Author Share Posted January 29, 2006 The dealer that I've been going to has treated me well. When I first took it in for the problem they said that my air-to-fuel ratio was "110%". I'm not sure what that means, but they said it's fine. I'll try them one more time and if they say nothing is wrong I'll drive 45 minutes to the next Subaru dealer. Ah, the joys of "east central Illinois". Link to comment Share on other sites More sharing options...
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