91LegLS Posted April 26, 2006 Share Posted April 26, 2006 Have a 91 Legacy 2.2. Have changed the air and fuel filter, new plugs and wires, Seafoamed the top end of the engine and crankcase, 44k in the injectors, tires properly inflated, just had the engine "scoped", tech found no problems. I'm lucky to get 220 on a full tank with highway driving. Trip meter usually says 185 when tank is empty. Tech pressure tested fuel system and no problems with leaks anywhere. Brakes are not dragging, they were recently inspected. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted April 26, 2006 Share Posted April 26, 2006 No check engine light? how old is the timing belt? i'd wonder if it is old or not tensioned properly? by brakes inspected what does that mean? did they actually pull the caliper apart and grease the slides or just inspect them by saying the function properly and have good rotors/pads? perfectly working brake systems can still drag. check that all tires rotate easily - bad bearings? O2 sensor? is the a/c on all the time? gas cap leaking? Quote Link to comment Share on other sites More sharing options...
91LegLS Posted April 26, 2006 Author Share Posted April 26, 2006 No check engine light? how old is the timing belt? i'd wonder if it is old or not tensioned properly? by brakes inspected what does that mean? did they actually pull the caliper apart and grease the slides or just inspect them by saying the function properly and have good rotors/pads? perfectly working brake systems can still drag. check that all tires rotate easily - bad bearings? O2 sensor? is the a/c on all the time? gas cap leaking? No check engine light, timing belt good, not recently changed but in good shape. Wheels rotate easily (brakes and bearings OK). HVAC is not using A/C (have automatic climate control and the ECONO button is engaged all the time). O2 sensor was evaluated and was reading correctly but I don't know how old it is. I work in a diesel repair shop and some of the techs think the O2 sensor should be replaced because of possible age issues (159K on the odometer) Quote Link to comment Share on other sites More sharing options...
idosubaru Posted April 26, 2006 Share Posted April 26, 2006 replacing the O2 isn't a bad idea. Quote Link to comment Share on other sites More sharing options...
nipper Posted April 26, 2006 Share Posted April 26, 2006 How many miles are on the car in general. Is the trunk empty? Are all the tires inflated? DO you have long life tires on the car (harder rubber, less rolling reistance) 02 sensor would not hurt. nipper Quote Link to comment Share on other sites More sharing options...
ron917 Posted April 26, 2006 Share Posted April 26, 2006 Any smoke or other sign of running rich? O2 sensor would be near the top of my suspect list. Check the engine temp sensor, the one used by the ECM, not the one that drives the temp gauge on the dash. On most cars, if the temp sensor fails open, the ECM thinks the temp is -40 degrees, and it runs a rich mixture. Quote Link to comment Share on other sites More sharing options...
nipper Posted April 26, 2006 Share Posted April 26, 2006 most times on the sooby, the car wont run if the gauge goes open or has a dead spot (never understood this, but i didnt write the software). Does your temp gauge on the dashboard read correctly ( a stuck open thermostat will affect gas milage too). nipper Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted April 26, 2006 Share Posted April 26, 2006 Yep, open t'stat can be hard to spot too. FEEL of the wheels after driving some, a hot wheel may indicate a draggy caliper. How did the old plugs look? consistent with each other? no carbon? Did the o'scope the O2 sensor? I'vre they can be 'lazy' and lead to problems. Maybe a search for a vacuum leak would be good? I dunno - everyone else has good ideas. Quote Link to comment Share on other sites More sharing options...
firstwagon Posted April 26, 2006 Share Posted April 26, 2006 Have a 91 Legacy 2.2. Have changed the air and fuel filter, new plugs and wires, Seafoamed the top end of the engine and crankcase, 44k in the injectors, tires properly inflated, just had the engine "scoped", tech found no problems. I'm lucky to get 220 on a full tank with highway driving. Trip meter usually says 185 when tank is empty. Tech pressure tested fuel system and no problems with leaks anywhere. Brakes are not dragging, they were recently inspected. How fast do you drive on the hwy? Going over 75 mph really kills my mileage. Also when you fill up you car, how much gas does it take? I've heard a lot of people complain about the guages on the 1st gen Legacys. My 91 will read empty after 250 miles but there's really a third of a tank left. ( it will only take 40 litres and it's a 60 litre tank). The averages out to about 25 mpg which is about as good as you'll get. Quote Link to comment Share on other sites More sharing options...
91LegLS Posted April 26, 2006 Author Share Posted April 26, 2006 Yep, open t'stat can be hard to spot too. FEEL of the wheels after driving some, a hot wheel may indicate a draggy caliper. How did the old plugs look? consistent with each other? no carbon? Did the o'scope the O2 sensor? I'vre they can be 'lazy' and lead to problems. Maybe a search for a vacuum leak would be good? I dunno - everyone else has good ideas. When the tech scoped the engine he also tested the temp sensor and said it was reading correctly and didn't see any problems. The temp gauge always seems to be on the "lower third" side. Tested the emmissions and everything showed normal (not running rich or lean). I have a wagon and the back is always empty. When I fill up, I fill the tank and it usually takes 10-12 gallons. I always record the odometer and trip meter reading on the receipts. When I replaced the plugs, there was no excessive deposits but the plugs were tan in color. They were also Delco's that weren't properly gapped. Changed the plugs in November 2005 (bought the car September 2005). Had the coolant tested in March and they said it was a little weak but the temp never seems to get higher than the halfway mark. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted April 26, 2006 Share Posted April 26, 2006 When the tech scoped the engine he also tested the temp sensor and said it was reading correctly and didn't see any problems. The temp gauge always seems to be on the "lower third" side. Tested the emmissions and everything showed normal (not running rich or lean). I have a wagon and the back is always empty. When I fill up, I fill the tank and it usually takes 10-12 gallons. I always record the odometer and trip meter reading on the receipts. When I replaced the plugs, there was no excessive deposits but the plugs were tan in color. They were also Delco's that weren't properly gapped. Changed the plugs in November 2005 (bought the car September 2005). Had the coolant tested in March and they said it was a little weak but the temp never seems to get higher than the halfway mark. Hmmm, the only thing here is the temp. Lower third MAY be open t'stat. I'd prefer you said it was at 40% and gets there quickly. Again, just a few degrees difference but it can matter. It depends a lot on the linearity of the gauge but I had this exact problem in a Dodge Avenger and the apparent guage difference was about 30% when bad and 40% after putting a new t'stat in. Oh yeah, I guess the tires are the correct size for the car? Carl Quote Link to comment Share on other sites More sharing options...
91LegLS Posted April 26, 2006 Author Share Posted April 26, 2006 Hmmm, the only thing here is the temp. Lower third MAY be open t'stat. I'd prefer you said it was at 40% and gets there quickly. Again, just a few degrees difference but it can matter. It depends a lot on the linearity of the gauge but I had this exact problem in a Dodge Avenger and the apparent guage difference was about 30% when bad and 40% after putting a new t'stat in. Oh yeah, I guess the tires are the correct size for the car? Carl So...when I get the coolant changed I should also get the t'stat replaced. I should still strongly consider having the O2 sensor replaced first, right? Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted April 26, 2006 Share Posted April 26, 2006 So...when I get the coolant changed I should also get the t'stat replaced. I should still strongly consider having the O2 sensor replaced first, right? That's a lotta mileage on both those items if they are original. I'd consider it - at least they'd be eliminated from further speculation. You can also test the t'stat in a pot of hot water if that interests you. Carl Quote Link to comment Share on other sites More sharing options...
Gnuman Posted April 27, 2006 Share Posted April 27, 2006 I see no mention of the type of transmission. Auto or Manual? O2 sensor is the most likely culprit. When you change the thermostat, be sure to use OEM Subaru. The aftermarket ones do not work as well, nor are they as reliable. The reason I asked about the transmission is that Auto trannies get a few MPG less than the Manual ones, as they have a bit more internal drag. Quote Link to comment Share on other sites More sharing options...
Andyjo Posted April 27, 2006 Share Posted April 27, 2006 i've been having this sort of problem.. i changed the O2 sensor.. nothing really changed, and i still get that silly fuel temp sensor CEL... someday i'll fix it :-\ Quote Link to comment Share on other sites More sharing options...
91LegLS Posted April 27, 2006 Author Share Posted April 27, 2006 I see no mention of the type of transmission. Auto or Manual? O2 sensor is the most likely culprit. When you change the thermostat, be sure to use OEM Subaru. The aftermarket ones do not work as well, nor are they as reliable. The reason I asked about the transmission is that Auto trannies get a few MPG less than the Manual ones, as they have a bit more internal drag. I have the Auto but I don't think I should be getting as low as 16, I have the fuel receipt to prove it. Is the O2 sensor difficult to get at? I understand I have only one. Quote Link to comment Share on other sites More sharing options...
nipper Posted April 27, 2006 Share Posted April 27, 2006 I have the Auto but I don't think I should be getting as low as 16, I have the fuel receipt to prove it. Is the O2 sensor difficult to get at? I understand I have only one. ive gottne as low as 12, but that is winter using the remote starter, i usually get 17-20 around town depending upon how i drive. Now town here is a stop sign on every corner, i still have no idea what the mileag is on the highway, anyone want to take my car on a run nipper Quote Link to comment Share on other sites More sharing options...
LosDiosDeVerde86 Posted April 27, 2006 Share Posted April 27, 2006 ive gottne as low as 12, but that is winter using the remote starter, i usually get 17-20 around town depending upon how i drive. Now town here is a stop sign on every corner, i still have no idea what the mileag is on the highway, anyone want to take my car on a run nipper yeah, i'm in this with you; as you can see in my Richness and Other Stuff thread. 17.5 city 21 hwy Quote Link to comment Share on other sites More sharing options...
LosDiosDeVerde86 Posted April 27, 2006 Share Posted April 27, 2006 also, don't be fooled by the gas guage. after 1/2 talk on mine i may as well not even look at it. it'll drop down to less than a quarter and i still have around 1/2 tank full. i have to watch my trip tick. 220-230 miles, it's time to fill up. normally 12.5 gallons. Quote Link to comment Share on other sites More sharing options...
91LegLS Posted April 27, 2006 Author Share Posted April 27, 2006 also, don't be fooled by the gas guage. after 1/2 talk on mine i may as well not even look at it. it'll drop down to less than a quarter and i still have around 1/2 tank full. i have to watch my trip tick. 220-230 miles, it's time to fill up. normally 12.5 gallons. I wish I could drive 220-230 miles on a tank. I'm lucky if I get 180. The mechanics I work with looked at my O2 sensor and they said it looks like the original (159K on the odometer). I'll be changing it soon and see what happens. Quote Link to comment Share on other sites More sharing options...
91LegLS Posted May 25, 2006 Author Share Posted May 25, 2006 I see no mention of the type of transmission. Auto or Manual? O2 sensor is the most likely culprit. When you change the thermostat, be sure to use OEM Subaru. The aftermarket ones do not work as well, nor are they as reliable. The reason I asked about the transmission is that Auto trannies get a few MPG less than the Manual ones, as they have a bit more internal drag. A couple weeks ago I had the original O2 sensor (confirmed by the mechanic) replaced. 159K on original engine. It made a big difference. I am now consistently getting 200-220 miles in city driving on 10 gallons. Highway MPG has increased to about 25. Idle set screw was also causing idle RPM to run at 1300. Mechanic adjusted idle screw to 450-500 rpm and the engine is now almost Lexus smooth (ran Seafoam in the top end a month ago). Quote Link to comment Share on other sites More sharing options...
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