cal_look_zero Posted February 21, 2012 Share Posted February 21, 2012 The night that I bought my 97 OBS, I filled up the tank in Bend, OR, and drove nearly 360 miles before I needed to fill up again. Being that the car was used to drive 2 - 5 miles at a time, I flogged it hard to clear the crud out of the engine; like 4th gear pulls to 80+. This was all during the 360 miles I got to that tank. Immediately upon getting back to Grants Pass and filling up, my fuel mileage dropped from about 27, to around 21. At that time, no modifications were made, I was driving it easier than I had coming back from Bend, and the vast majority of my driving is on the freeway about 28 miles each way; per day. A few weeks back I did a large amount of repair work to the chassis: Fixed the bad inner tie rods, installed all new front brakes and wheel bearings, lubed critical points in the front end (ball joints, brake slide pins) and installed a new clutch. I'm running 60k mile tires inflated to 38psi, and they're 205/55/16 on WRX rims. I replaced the PCV valve with a Subaru part, replaced the Fram air filter with a Wix, am running Rotella T5 and a Bosch oil filter, and use cruise every chance I get. Cliffs: OBS got 27mpg or better after purchase/hard driving Get home and fuel mileage drops Done everything right IMO and repaired everything I can think of. So being that the car is OBDII, I'm under the impression that any bad sensor like a coolant temp, knock, or o2 would throw some sort of code alerting a bad condition. At this point, I'm hovering around 18-19mpg; 90% freeway driving at 70mph or so. In other words, I'm stumped and leaning towards trading this for a more fuel efficient lifted F350 or Freightliner tractor. On a slightly related note, my 2003 Mitsubishi Montero Sport which got around 18mpg at purchase, is down around 13mpg as well. Could it be that we just have really REALLY crappy gas where I live? Quote Link to comment Share on other sites More sharing options...
ivans imports Posted February 21, 2012 Share Posted February 21, 2012 check the fuel fillter out if it gets pluged a bitt it make the pump run at higher presshure and it will get bad milage idling around because it runs to high of preshure low rpms and not enuff on high rpms makes the milage suck Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted February 21, 2012 Author Share Posted February 21, 2012 check the fuel fillter out if it gets pluged a bitt it make the pump run at higher presshure and it will get bad milage idling around because it runs to high of preshure low rpms and not enuff on high rpms makes the milage suck I'll replace the fuel filter and see if that helps. I forgot to mention above also, that after the mpgs were consistently crap, I opted to desnorkus, build a UEL header, and install a freer flowing muffler. So far, no change in mpgs positive or negative. Quote Link to comment Share on other sites More sharing options...
CoupedUpSubie Posted February 21, 2012 Share Posted February 21, 2012 What are you running for fuel? Some stations have 100% gasoline while others have E10 gasoline. The switch to E10 happened in Maine before I got my subaru so I am not sure what I would be getting with straight gas. The jetta with a 2.0L got 33-35 mpg on straight and dropped to 28-30 mpg with the E10. Also look into if your local stations run a "winter" blend as this also effects my fuel mileage. Once you replace your fuel filter I reccomend running seafoam or some other fuel system cleaner made for the fuel you use. E10 fuel requires special formulas. If you find that your filter is clogged after this then you know the cleaner did something for you. Yeah it is another $25 but if you are getting 4-5 mpg more then the savings will return. Quote Link to comment Share on other sites More sharing options...
jamesm113 Posted February 21, 2012 Share Posted February 21, 2012 Did you get an alignment after replacing the inner tie rods? How are the spark plugs and wires? Quote Link to comment Share on other sites More sharing options...
TheLoyale Posted February 21, 2012 Share Posted February 21, 2012 What does the exhaust smell like? Rich, burns your eyes? If so, check/replace the MAF with a lesser milage one from the Junkyard for about $40. I had a similar issue with my '95 Outback EJ22. 100 miles would be Half tank Also, check the IAC. These were the two major culprits with my extremely poor MPG, 16MPG with a Flat-4 Engine = BS! Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted February 21, 2012 Author Share Posted February 21, 2012 Car is aligned, plugs and wires are newer (3k miles), fuel filter was clogged a bit so I replaced with Wix. Exhaust smells normal, but I shot the MAF with MAF cleaner for good measure. Car has 230k miles and noted blowby. I installed the catch cans I've had for awhile (one at valve cover T into airbox and one at primary breather into airbox) and noted improvement in throttle response after a couple of Italian tune up pulls. Going to order a bluetooth OBDII dongle and do some real time CBM to see what the computer is doing. Moreso out of curiosity at this point, but also for the sake of seeing if I have a sensor that's within parameters but causing a rich condition. EDIT: We have E10 here. I had to get a whole new dyno tune and remap done on my bike just to get it to run, so I'm sure all my cars hate it as well. Causes dieseling in my F100 if I have my timing even slightly advanced. Quote Link to comment Share on other sites More sharing options...
littlegto Posted February 21, 2012 Share Posted February 21, 2012 I have a 2.2 1995 Legacy wagon getting very poor mileage and can smell fuel when it is running but witness no leaks. Changed the fuel filter a year ago and made sure that the hoseclamps were tight. No check engine light and currently only driving short stop and go trips. For the mass airflow, will the cleaner suffice (and what was the brand name) or should I get another? What is the IAC and how much? A friend mentioned it could be 02 sensors but wouldn't that cause a CEL? I am going to change the plugs and wires and fuel filter again but note that the car runs great currently other than this issue. Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted February 21, 2012 Author Share Posted February 21, 2012 I have a 2.2 1995 Legacy wagon getting very poor mileage and can smell fuel when it is running but witness no leaks. Changed the fuel filter a year ago and made sure that the hoseclamps were tight. No check engine light and currently only driving short stop and go trips. For the mass airflow, will the cleaner suffice (and what was the brand name) or should I get another? What is the IAC and how much? A friend mentioned it could be 02 sensors but wouldn't that cause a CEL? I am going to change the plugs and wires and fuel filter again but note that the car runs great currently other than this issue. http://www.oreillyauto.com/site/c/detail/CRC0/05110.oap?******=Search_maf+cleaner_-1_3112&keyword=maf+cleaner Is what I used. Small improvement on my Montero Sport.. Does anyone have a method for testing functionality of the MAF? Quote Link to comment Share on other sites More sharing options...
uniberp Posted February 22, 2012 Share Posted February 22, 2012 I never hear about replacing Soob injectors, but in my history, injector wear makes for bad mileage. Try some Techron. Car is aligned, plugs and wires are newer (3k miles), fuel filter was clogged a bit so I replaced with Wix. Exhaust smells normal, but I shot the MAF with MAF cleaner for good measure. Car has 230k miles and noted blowby. I installed the catch cans I've had for awhile (one at valve cover T into airbox and one at primary breather into airbox) and noted improvement in throttle response after a couple of Italian tune up pulls. Going to order a bluetooth OBDII dongle and do some real time CBM to see what the computer is doing. Moreso out of curiosity at this point, but also for the sake of seeing if I have a sensor that's within parameters but causing a rich condition. EDIT: We have E10 here. I had to get a whole new dyno tune and remap done on my bike just to get it to run, so I'm sure all my cars hate it as well. Causes dieseling in my F100 if I have my timing even slightly advanced. Quote Link to comment Share on other sites More sharing options...
Ricearu Posted February 22, 2012 Share Posted February 22, 2012 does your freeway have traffic? My 90 lego got 25-26 out on the open road but get it around dallas, in city traffic and it got 18-20... Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted February 22, 2012 Author Share Posted February 22, 2012 does your freeway have traffic? My 90 lego got 25-26 out on the open road but get it around dallas, in city traffic and it got 18-20... Oh god no, nothing like 20 or 30. Quote Link to comment Share on other sites More sharing options...
NoCo Posted February 22, 2012 Share Posted February 22, 2012 you need a scanner to test your MAF. first check with KOEO and look at the barrometric pressure and compare to the local pressure, i use the third dial on the "decoration" weather staion that i keep i my paint booth for temp and humidity. i dont know how high bend is but here in the front range i expect about 24.5"Hg. next check at idle you will have to look for a spec but id expect to see 5g/sec. and as for cleaning you MAF alittle isopropal alcohol on a q-tip has always served me well. good luck tell us wha you find Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted February 22, 2012 Author Share Posted February 22, 2012 you need a scanner to test your MAF. first check with KOEO and look at the barrometric pressure and compare to the local pressure, i use the third dial on the "decoration" weather staion that i keep i my paint booth for temp and humidity. i dont know how high bend is but here in the front range i expect about 24.5"Hg. next check at idle you will have to look for a spec but id expect to see 5g/sec. and as for cleaning you MAF alittle isopropal alcohol on a q-tip has always served me well. good luck tell us wha you find Bend is about 3600' and Grants Pass and Medford are 11-1200'. I did order an OBD - USB scanner and plan to... find... some higher quality scanning software that will allow real time data collection on multiple parameters. Quote Link to comment Share on other sites More sharing options...
NoCo Posted February 22, 2012 Share Posted February 22, 2012 vato zone will scan it for ya. you may have to talk them thru pulling live data...google your local baro pressure...as long as your car doesnt have a MAP sensor the reading is taken from the MAF...make sure you tell us what you find Quote Link to comment Share on other sites More sharing options...
john in KY Posted February 22, 2012 Share Posted February 22, 2012 My 95 fuel mileage recently took a major hit similar to yours. Turned out the problem was the vacuum line to the FPR came disconnected. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted February 22, 2012 Share Posted February 22, 2012 (edited) 2 thoughts, My 95 fuel mileage recently took a major hit similar to yours. Turned out the problem was the vacuum line to the FPR came disconnected. 1/ i'm going to check my 96 ej22 engine in my 97 GT for this today. but i'm pretty sure mine is running rich all the time. 2/ since you only had one tank of good mileage, is there any chance you didn't completely fill the tank when you filled up? 13.33 gals at 27 miles per gallon = 360 miles. but that means there were still 2.5 gals still in the tank. was the low fuel light on when you filled up? Edited February 22, 2012 by johnceggleston Quote Link to comment Share on other sites More sharing options...
LeolaPA Posted February 22, 2012 Share Posted February 22, 2012 My 95 fuel mileage recently took a major hit similar to yours. Turned out the problem was the vacuum line to the FPR came disconnected. What is the "FPR?" Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted February 22, 2012 Author Share Posted February 22, 2012 2 thoughts, 1/ i'm going to check my 96 ej22 engine in my 97 GT for this today. but i'm pretty sure mine is running rich all the time. 2/ since you only had one tank of good mileage, is there any chance you didn't completely fill the tank when you filled up? 13.33 gals at 27 miles per gallon = 360 miles. but that means there were still 2.5 gals still in the tank. was the low fuel light on when you filled up? I consistently log my fuel mileage through an app on my phone and started with the first tank when I bought it. I don't believe my car even has a low fuel light. I'm consistently at around 260 miles and 13.5 gallons. Quote Link to comment Share on other sites More sharing options...
jamesm113 Posted February 22, 2012 Share Posted February 22, 2012 Do you have a EJ22 or EJ25? And the tank is 15.9 gals, so you still have nearly 2.5 gals left, so maybe the low fuel light isn't getting the chance to come on Quote Link to comment Share on other sites More sharing options...
nipper Posted February 23, 2012 Share Posted February 23, 2012 Does your engine oil change like gas? Put the snorkus back on untill we figure this out, too many changed variables can make it impossible to diagnose sometimes. I get 18 around town with a stop sign on every corner, 24-25 above 70, below 70 27-28. A none OE air folter can screw up the intake sensor. Check for dragging brakes. The high flow stuff is a bit of a waste on a subaru unless you put in cams. Quote Link to comment Share on other sites More sharing options...
nipper Posted February 23, 2012 Share Posted February 23, 2012 Why running 38 PSI on the tires, that is awfully high and can be dangerous. Quote Link to comment Share on other sites More sharing options...
NoCo Posted February 23, 2012 Share Posted February 23, 2012 i like the idea of a vacuum leak causing poor milage. very possible. you can take carb cleaner and spray you engine(not in it) while it is running. if the engine speeds up then you are close to the vacuum leak. dragging brakes or binding drive train could also do it. can you put it in nuetral and push it? let us know i know i get 27-28 at 65mph and 23-24 at 75mph. i contibute that to the forester's complete lack of areodynamics lol. let us know what you find Quote Link to comment Share on other sites More sharing options...
aprezzal Posted February 24, 2012 Share Posted February 24, 2012 I know when they went to the 10% alcohol here in NJ my fuel economy took a hit (30MPG Average to 26-27 average) maybe its the fuel contributing to most of your MPG woes.. Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted February 24, 2012 Share Posted February 24, 2012 I blame ethanol 100% sure hope they don't approve 15% required ethanol blend. Will drop even more mpg if that happens. Quote Link to comment Share on other sites More sharing options...
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