nh484000 Posted July 4, 2015 Share Posted July 4, 2015 Hi All- My 2008 LGT 5MT with approx 160k miles has limited power under 3,000 RPM. I've had my car since almost new so I know something is wrong. Stock, all maintenance done religiously, and Exeter, NH Subaru can't seem to find the problem. One day I was driving on the highway is it felt like someone flipped a switch. No check engine light, car seems to idle fine and run ok. Over 3,000 RPM the car is fine. I can easily wind 4th right out so I'm guessing the fuel pump is fine. Most relevant post I can find is this one. http://legacygt.com/forums/showthread.php/need-advice-find-odd-fueling-problem-242575.html?t=242575&highlight=test+sensor I replaced the front O2 sensor about 25k miles ago and have another one sitting on the shelf if needed but I wanted some input before I start throwing parts to it. The replacement part was a Denso and it fixed the CEL I had when it went. This is literately the only thing other than oil, filters, plugs, brakes and tires that I have done to the car. I just logged the car but honestly don't really know what I am looking at. I can see the car is making boost (about 22 psi) so its not a boost problem. I usually work on diesel so I have an idea of what is going on but since this car has never really had a problem I haven't worked on it much. Not sure if the cat is clogged. I only logged O2, boost and cat temp but maybe it would help if I logged fueling too. I just drove around the block for a few mins. If I need to log it more or take different reading I can do that. Any insight would be appreciated. Thank you and happy 4th.DataLog-Jul_04_2015_171539.csv Link to comment Share on other sites More sharing options...
Phillip J. Fry Posted July 4, 2015 Share Posted July 4, 2015 have you changed the air filter recently? cleaned the maf? can try a barryman b12 fuel system cleaner as well. after looking into a new maf the car seems to be driving better. im starting to think some others are correct. to replace these at normal interval. just starting with the basics man. some will say boost/vacuum leak. can check for that too. Link to comment Share on other sites More sharing options...
nh484000 Posted July 4, 2015 Author Share Posted July 4, 2015 Forgot to add that I did just clean the MAF sensor and put in a new air filter. I did try to injector cleaner about 5 tanks ago after this started. No change. Thanks. Could be a vacuum leak. I'll have to get some carb cleaner out. Link to comment Share on other sites More sharing options...
nh484000 Posted July 5, 2015 Author Share Posted July 5, 2015 So I just changed the O2 sensor and there is no real different. I did take the car our for a drive for a few mins with a few full throttle runs and logged everything I could with the app that I have. Nothing really stands out to me.DataLog-Jul_05_2015_112952.csv Link to comment Share on other sites More sharing options...
Phillip J. Fry Posted July 5, 2015 Share Posted July 5, 2015 have you reset the ecu after the o2 change? i dont know how long it takes for the ecu to adjust. Link to comment Share on other sites More sharing options...
nh484000 Posted July 5, 2015 Author Share Posted July 5, 2015 Well I disconnected the battery for about 3 hours this afternoon and then took the car for a drive for about 10 mins. Car ran fine and feels like new again. Hopefully it stays that way. Going to take it to work tomorrow and see. Thank you. Link to comment Share on other sites More sharing options...
Phillip J. Fry Posted July 7, 2015 Share Posted July 7, 2015 good to hear man. hope thats all it needed. good luck. Link to comment Share on other sites More sharing options...
FJuan Posted July 7, 2015 Share Posted July 7, 2015 It takes over 3 on/off cycles for the ECU to learn after you reset it. Right now you're running in the learning cycle which is the safe mode for now. After a couple of days you will know if it fix the problem or not. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
Phillip J. Fry Posted July 9, 2015 Share Posted July 9, 2015 you are on stock bpv? if so i think that could be a problem too. Link to comment Share on other sites More sharing options...
bigbadboss101 Posted July 10, 2015 Share Posted July 10, 2015 So in learning mode after battery disconnect should one drive more aggressively? Link to comment Share on other sites More sharing options...
Max Capacity Posted July 10, 2015 Share Posted July 10, 2015 Yes. I do. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Phillip J. Fry Posted July 10, 2015 Share Posted July 10, 2015 So in learning mode after battery disconnect should one drive more aggressively? i always do. about 3-5 pushes to 100 with wot usually does it. then the other things will fall into place over the next 100 miles. Link to comment Share on other sites More sharing options...
nh484000 Posted July 11, 2015 Author Share Posted July 11, 2015 I've put about 300 miles on the car in the last week and it's still running well. I am also still on the stock bpv. So maybe it was just another O2 sensor. Link to comment Share on other sites More sharing options...
gimpydingo Posted July 11, 2015 Share Posted July 11, 2015 So in learning mode after battery disconnect should one drive more aggressively? Maybe somewhat related. Do take it on a nice long trip, at least 30 - 40 mile cruise to help set everything. Even though I had a few hundred miles on my car after a reset, I didn't drive it far/long/hard enough to get a couple of sensor to activate for my SMOG. So it failed and I took or on a nice long trip, checked sensors and all was good. Link to comment Share on other sites More sharing options...
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