BIGBLUE1212 Posted October 8, 2006 Share Posted October 8, 2006 hey everyone, i noticed that my car is getting about 18mpg on average, its a 97 legacy gt 2.5, i thought this car would do alot better.....and 18mpg is mostly highway doing about 65mph (110kmh) I dont get it.....the other day i filled up the tank from about an 8th left and i put just under 10 gallons. The car is supposed to have a 15 gallon tank.....where did the other third of a tank go?.....i think the guage is wrong/broken....does anyone else have these problems? Quote Link to comment Share on other sites More sharing options...
ericem Posted October 8, 2006 Share Posted October 8, 2006 hey everyone, i noticed that my car is getting about 18mpg on average, its a 97 legacy gt 2.5, i thought this car would do alot better.....and 18mpg is mostly highway doing about 65mph (110kmh) I dont get it.....the other day i filled up the tank from about an 8th left and i put just under 10 gallons. The car is supposed to have a 15 gallon tank.....where did the other third of a tank go?.....i think the guage is wrong/broken....does anyone else have these problems? i was thinking the same, im trying and u should try, to drive around until the tank is empty, and see how many more km u get then we it shows empty, and definityl bring a jug of fuel. Might be moisture in the gas tank also. Quote Link to comment Share on other sites More sharing options...
monytontanarx Posted October 8, 2006 Share Posted October 8, 2006 hey everyone, i noticed that my car is getting about 18mpg on average, its a 97 legacy gt 2.5, i thought this car would do alot better.....and 18mpg is mostly highway doing about 65mph (110kmh) I dont get it.....the other day i filled up the tank from about an 8th left and i put just under 10 gallons. The car is supposed to have a 15 gallon tank.....where did the other third of a tank go?.....i think the guage is wrong/broken....does anyone else have these problems? i own the exact year and model and mine gets a little over 30 mpg so you either pulled a lemon or your gas gauge is the problem. Quote Link to comment Share on other sites More sharing options...
nipper Posted October 8, 2006 Share Posted October 8, 2006 hey everyone, i noticed that my car is getting about 18mpg on average, its a 97 legacy gt 2.5, i thought this car would do alot better.....and 18mpg is mostly highway doing about 65mph (110kmh) I dont get it.....the other day i filled up the tank from about an 8th left and i put just under 10 gallons. The car is supposed to have a 15 gallon tank.....where did the other third of a tank go?.....i think the guage is wrong/broken....does anyone else have these problems? do a search. The gas gauges get contaminated over the years and become innacurate. Techron or Chevron ( i think) has an additive that cleans the gauge. nipper Quote Link to comment Share on other sites More sharing options...
subiefan Posted October 8, 2006 Share Posted October 8, 2006 I've got the same thing going on. Just seems like the gas gauge is dropping too fast. Need to measure the mileage with the trip odometer and the gallons at fill-up. I'm guessing that either my gas guage is three resistors shy of a full load or my o2 sensor is going kaploee. But I'm not usually the one that takes it to the gas station, and when I do, I never remember. Will get around to it eventually. Back on to your question: I have seen an ej22 get 17-18 mpg before. Reset the computer and all was well.:-\ My best guess is that it got a batch of bad gas run through it. Your are measuring your mpg by the gas gauge, correct? This is how you measure mpg the right way: 1.) Fill up until pump shuts off. Don't top off. 2.) Reset trip odometer to 0. 3.) Drive around until you need to fill up again. 4.) Go ahead and fill up again like before. Technically, you should use the same gas pump as before. 5.) Write down the number of gallons that your car held. 6.) Now divide the miles on your trip odometer by the number of gallons you just put in. 7.) You now have your MPG. If your mpg turns out to be really low, you could try and reset your ECU. I've seen it work, and probably would if bad gas was the problem (after fill-up with clean gas, of course). If your o2 sensor has never been replaced, it's probably getting lazy and causing the trouble. Sorry 'bout the long-winded post. Cheers. Quote Link to comment Share on other sites More sharing options...
ericem Posted October 8, 2006 Share Posted October 8, 2006 I've got the same thing going on. Just seems like the gas gauge is dropping too fast. Need to measure the mileage with the trip odometer and the gallons at fill-up. I'm guessing that either my gas guage is three resistors shy of a full load or my o2 sensor is going kaploee. But I'm not usually the one that takes it to the gas station, and when I do, I never remember. Will get around to it eventually. Back on to your question: I have seen an ej22 get 17-18 mpg before. Reset the computer and all was well.:-\ My best guess is that it got a batch of bad gas run through it. Your are measuring your mpg by the gas gauge, correct? This is how you measure mpg the right way: 1.) Fill up until pump shuts off. Don't top off. 2.) Reset trip odometer to 0. 3.) Drive around until you need to fill up again. 4.) Go ahead and fill up again like before. Technically, you should use the same gas pump as before. 5.) Write down the number of gallons that your car held. 6.) Now divide the miles on your trip odometer by the number of gallons you just put in. 7.) You now have your MPG. If your mpg turns out to be really low, you could try and reset your ECU. I've seen it work, and probably would if bad gas was the problem (after fill-up with clean gas, of course). If your o2 sensor has never been replaced, it's probably getting lazy and causing the trouble. Sorry 'bout the long-winded post. Cheers. thanks ill give that a shot, but would filling the tank right up to the top cause that issue? I usually go way past after it clicks. So to reset the ECU how long do i unplug the battery for? Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted October 8, 2006 Share Posted October 8, 2006 If your mpg turns out to be really low, you could try and reset your ECU. Cheers. i just finished 2 bad mpg tanks. the first was due to a misfire on #4 about 10 gals. 16.75 mpg. new plugs and wires corrected that. the second was just the after the first, drpove 136 miles on 8 gals. that's 17mpg, very little hiway. question, will the ecu re-learn and start delivering good mpg even if i don't reset? how long will it take? reset is easy, but i was just wondering how long it wolud take for the computer to correct itself. and if it doesn't is that an indicator of bad o2 sensor. thanks, john Quote Link to comment Share on other sites More sharing options...
ericem Posted October 8, 2006 Share Posted October 8, 2006 Again, how do i reset the ECU, just unplug the battery? ANd for how many minutes? Quote Link to comment Share on other sites More sharing options...
nipper Posted October 8, 2006 Share Posted October 8, 2006 Again, how do i reset the ECU, just unplug the battery? ANd for how many minutes? 30 minutes will do it, though most will let it go overnight. i hope your not like me where you have to spend 20 minutes resetting the stero grrrrr nipper Quote Link to comment Share on other sites More sharing options...
ericem Posted October 8, 2006 Share Posted October 8, 2006 30 minutes will do it, though most will let it go overnight. i hope your not like me where you have to spend 20 minutes resetting the stero grrrrr nipper nope, i know what station i listen to, its just a OEM stereo, nothing special. Quote Link to comment Share on other sites More sharing options...
Manarius Posted October 8, 2006 Share Posted October 8, 2006 Pull the fuse to the ECU for at least 45 minutes. Put the fuse back in and start the car in park. Leave it until it's warm then shut it off. If you reset the ECU, you HAVE TO make it relearn or else your car will run crappy. Quote Link to comment Share on other sites More sharing options...
ericem Posted October 9, 2006 Share Posted October 9, 2006 Pull the fuse to the ECU for at least 45 minutes. Put the fuse back in and start the car in park. Leave it until it's warm then shut it off. If you reset the ECU, you HAVE TO make it relearn or else your car will run crappy. wheres the fuse? Inside or the fuse box under the hood? Thanks. Quote Link to comment Share on other sites More sharing options...
BIGBLUE1212 Posted October 9, 2006 Author Share Posted October 9, 2006 what does reprogramming or letting the ECU relearn everything intail?......do i just do that idle till warm up thing and its reprogrammed? Quote Link to comment Share on other sites More sharing options...
ericem Posted October 9, 2006 Share Posted October 9, 2006 what does reprogramming or letting the ECU relearn everything intail?......do i just do that idle till warm up thing and its reprogrammed? guess thats what hes saying, so unplug ur battery or pull the fuse for 45 mins, then put the fuse back in, turn on the car, and let it idle till it warms up then turn it off. Quote Link to comment Share on other sites More sharing options...
Manarius Posted October 9, 2006 Share Posted October 9, 2006 The fuse for the ECU is in the kickbox under the dash. As I recall, it's like position 15 or something. Pull that fuse for 45 minutes so it'll just reset the ECU, not the entire system. Then, after you've done that, put the fuse back in. Put the car in park and turn off all accessories. Turn on the car and just let it sit until it gets warm. Once it reaches operating temp, shut it off (~10 minutes should be enough). This stuff is all on Josh's website, it would be nice if you guys would look so I wouldn't have to keep repeating it. Quote Link to comment Share on other sites More sharing options...
BIGBLUE1212 Posted October 9, 2006 Author Share Posted October 9, 2006 link please Quote Link to comment Share on other sites More sharing options...
BIGBLUE1212 Posted October 9, 2006 Author Share Posted October 9, 2006 position 15 is: meter and airbag indicator light, 16 is :engine ignition system and srs airbag....which one is it? Quote Link to comment Share on other sites More sharing options...
BIGBLUE1212 Posted October 9, 2006 Author Share Posted October 9, 2006 im also thinking of putting a fuel additive in to clean out the fuel system i have a suspicion my fuel guage isnt working properly....i fill it from practically empty and i can only put 10 gallons in instead of 15 Quote Link to comment Share on other sites More sharing options...
unobtainium Posted October 9, 2006 Share Posted October 9, 2006 [...]i have a suspicion my fuel guage isnt working properly.... There are two fuel senders in your car because the tank has a hump in the middle. Your symptoms are like mine were before I took both senders out and cleaned (carefully!) the potentiometers. The needle would point to empty at 260 miles and the yellow "low fuel" light would go on at about 275. Then the car would take only about twelve gallons of the 15.9 it's supposed to accept. After cleaning, the needle points to 1/4 at about 275 miles and the yellow light goes on at 320. That is much more reasonable. BTW my car (the '93) gets 25-26 MPG calculated as discussed in this thread. Quote Link to comment Share on other sites More sharing options...
Manarius Posted October 9, 2006 Share Posted October 9, 2006 position 15 is: meter and airbag indicator light, 16 is :engine ignition system and srs airbag....which one is it? Oh, duh, your car is a 97 2.5 GT. God only knows how to reset it and relearn the ECU on that car. I was assuming that you had a 90-94 legacy. You're going to have to ask someone with a manual to help you out on that one. I wouldn't reset the ECU until you learn how to relearn it. However, it would be smart of you to read the kick panel and look for the slot that says "ECU." Quote Link to comment Share on other sites More sharing options...
subiefan Posted October 9, 2006 Share Posted October 9, 2006 Reset procedure is the same for OBDI and OBDII if you don't want codes. Just disconnect ground cable at battery or pull the ECU fuse(s). There might be more than one. Don't know for sure. Personally, I always do the battery deal. The only thing I have to reset is the stereo, but if you have a keyless entry/security package, it could cause issues. OBDII doesn't have to idle til warm like OBDI. I usually let them anyway, but the car actually relearns most of it's programming on the road. About topping off....just say no. It won't hurt your fuel mileage, but could damage parts of the evaporative system. Plus it's not good for the gas station's systems either. A lot of times that fuel that you top off with doesn't even go into your tank. It feeds right back down into the station's tanks, and you pay for gas you don't get. Not good with the prices these days. It would make your mileage appear lower, as the pumps says you put more gallons of fuel in than you actually did. If you think you got bad gas, a fuel system cleaner wouldn't hurt. Be careful with that stuff, though. If you don't run your engine hot enough (short trips around the block, etc.), it can actually gunk up your injectors and whatnot worse than before. Jeeps are bad abou it because they run so cool. Seafoam and MM are more oil-based cleaners, and don't tend to do this. If your bad mpg doesn't go away, I'd start to suspect a lazy o2 sensor. If it turns out to be your gauge that's loony, there's some stuff that will clean up your senders...Techron, I think. I think Nipper here has recommended it. I just live with mine. I live out in the middle of nowhere, and don't like to let it get too low anyway. Quote Link to comment Share on other sites More sharing options...
BIGBLUE1212 Posted October 10, 2006 Author Share Posted October 10, 2006 ok, i bought a fuel additive that is supposed to clean the injectors, valves, fuel line, pumps etc. so if nothing changes it has to be the oxygen sensor. If it is the oxygen sensor would it be the very expensive mass air flow sensor or is it another sensor? Quote Link to comment Share on other sites More sharing options...
subiefan Posted October 10, 2006 Share Posted October 10, 2006 Fuel additive is fine. Just try not to do too much "around the corner" driving. If you don't get the engine up to temperature, that stuff likes to gunk up. Like I said...do a computer reset. Go ahead and do that now, if you haven't. Then, if you still don't get any good results, your o2 sensor is probably going kurpluee. The MAF is something completely different. It's not involved here. The o2 sensor I'm talking about is the one in the exhaust...the front one, not the rear heated one. The heated o2 sensor rearely fails. The front one is about $80 USD. Don't know what that is in Canadian, and as usual, prices vary from dealer to dealer. I'm pretty sure aftermarket universals from Autozone and such are ok too. Quote Link to comment Share on other sites More sharing options...
BIGBLUE1212 Posted October 10, 2006 Author Share Posted October 10, 2006 is it difficult to install the o2 sensor yourself? and is there anywher i can get a walkthrough? Quote Link to comment Share on other sites More sharing options...
Manarius Posted October 10, 2006 Share Posted October 10, 2006 O2 sensor is a joke. Undo O2 sensor nut. Pull out old sensor. Unplug old sensor. Put nut around new sensor. Plug in new sensor. Tighten new sensor to the exhaust. It's that simple. Quote Link to comment Share on other sites More sharing options...
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