usps Posted October 16, 2013 Share Posted October 16, 2013 Hello everyone I have a 95 subaru legacy wagon this is a right hand drive mail car my wife delivers mail and I fix the car when she tears it up . I have been through many issues with this car and resolved most the one I can't get is a fuel trim code . For a little background we currently have 2 right hand subes on the road one she drives on her route (a 97 ), and one I drive to work which is her back up one( the 95 ). I have driven this 95 for six months at a time no problems then when she gets it on the route with aggressive driving and lots of starts and stops it starts acting as though it's loading up won't idle and just won't go this is where I believe the fuel trim code comes in . Keep in mind I have changed of course the simple stuff plugs wires filter ect. but also oxygen sensors MAF sensor TPS , cam sensor , crank sensor,IAC valve ,MAP knock sensor, computer, coil , ignition module probably more can't think of everything and just recently cleaned the EGR valve . Not sure what else to try any suggestions would be appreciated . Link to comment Share on other sites More sharing options...
Legacy777 Posted October 20, 2013 Share Posted October 20, 2013 Welcome to the USMB. Fuel trim codes are kind of tough to diagnose. Do you have an exact trouble code you can share? PXXXX One thing you may want to try is checking the grounds throughout the car chassis and engine chassis. If the wiring is the same as the first gen Legacy (90-94) the ECU grounds to the back of the intake manifold on the driver's side down near where it bolts to the head. The engine grounds to battery through the starter. So if any of these ground points have extra resistance in them, it could be causing issues. If you have a multimeter you can check the wiring resistance through the various ground wires to see if they're ok. Also, adding an extra ground wire for the main grounding does sometimes help. I had a friend that would get a random shift solenoid code on his 93 legacy. We found the ground wire between the chassis and transmission was broken. We fixed that wire and no more code. Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 21, 2013 Share Posted October 21, 2013 It would be really helpful to have the exact code. Do you have any other codes besides the fuel trim code? Most of the time a fuel trim code will be due to a vacuum leak. And there are plenty of places on an EGR engine where a vacuum leak can occur. Check carefully for any cracks splits or loose fit. Throttle body cleaner is useful for finding leaks. Just spray it on the hoses and around the manifold and throttle body gaskets. If any of the hoses are hard its a good idea to replace them. Also be sure all of the breather hoses and PCV hoses that attach to the intake tube are in good shape and attached where they should be. Link to comment Share on other sites More sharing options...
MilesFox Posted October 21, 2013 Share Posted October 21, 2013 The ground wire mentioned above will connect on the right hand side (lookig at motor)of the intake near the #4 injector (rearmost). and the bolt for it is horizontal and perpendicular to the engine. 12mm tool. try cleaning the ontacts on the pigtails to the cmponents. One especially to consider is the engine temp sensor, which is under the intake at the rear ont he water crossober pipe lust below and to the left of the throttle body. It will be hiding under the bundle of wires that connect on the bellhousing Link to comment Share on other sites More sharing options...
usps Posted October 21, 2013 Author Share Posted October 21, 2013 Thank you all for your posts on this topic , I ran my code scanner again to see the exact code it was P0170 says fuel trim bank 1. And now after this last episode when my wife was about half way through her route it started acting up like loading up and giving it throttle and it just didn't want to go she stopped at one point and it would not restart fired but wouldn't start so she left it there and got help to finish the route . I went out that evening and it started right up run like a top but along with that P0170 code I now have a misfire code for cylinders 1,2,3 which it must have acquired when she was trying to run it. I have been over a lot of the vacuum lines but will do so again as well as check the grounds thanks again for your help. Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 21, 2013 Share Posted October 21, 2013 That description sounds like the fuel pump is bad. Checking pressure may only work when the pump is hot, since that's when the problem happens. Checking pressure with a cold pump may not show there is a problem, but its worth a try. Should have about 35 psi at idle. Pull the vacuum line off the FPR and it should jump up to about 43-45. Link to comment Share on other sites More sharing options...
usps Posted November 5, 2013 Author Share Posted November 5, 2013 I had to order me a new fuel pressure tester so I haven't checked the fuel pressure yet but I have some new info . Up until now the car only acted up for my wife well the other day I got behind a wreck and had to sit idling in traffic for about 30-40 min. After sitting there that long the car developed a miss that started getting worse until I decided I'd better turn around before the car shuts off . About 1-2 miles after turning around and heading up the road it straightened up . I decided to to the same test at home and let it idle till it started messing up then I opened up the hood to look around and shortly it straightened up so I closed hood again and within a few min. it started missing again . So I'm thinking something in the engine compartment is getting hot . I iced the coil and ignition module didn't help do you think the fuel ( filter etc. ) could be getting to hot or does it have to be electrical related ? I did watch my scan tool temp. and it was reading fine and the fan was kicking in and out properly . Link to comment Share on other sites More sharing options...
usps Posted December 4, 2013 Author Share Posted December 4, 2013 Well I got my fuel pressure gauge and upon checking the pressure my results showed that no matter what I did the pressure stayed at 25 lbs . Pressure didn't change when unhooking FPR at all and it would actually drop a little when revving the engine no change even when pinching off the return line . So I replaced the fuel pump with a new one and retested all tests proved good so I think your right fuel pump it was . So far no more symptoms been about two weeks now . Thanks very much for the advice just end wanted to give some closure on this matter. Link to comment Share on other sites More sharing options...
Fairtax4me Posted December 4, 2013 Share Posted December 4, 2013 Thanks for updating us! Glad to hear that its fixed! Link to comment Share on other sites More sharing options...
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