Cobrae Posted December 23, 2015 Share Posted December 23, 2015 (edited) Just picked up a 2002 Legacy GT Limited and it drove fine for the first month then just went insane. Its bucking and stalling like mad and getting 14ish mpg. I scanned it and got a few codes it is misfiring in all 4 cylinders and running rich. Only codes it gave. I have since replaced the coil, plugs, wires, Fuel pressure regulator, throttle body, MAP, and TPS. Nothing has changed. I'm at a bit of a standstill the only things left I could find searching is injectors or the front o2 sensor. I do have a parts car an 03 Legacy L that ran amazing it just had suspension problems and no clutch. I just don't see all 4 injectors failing at once so could it be the front o2 sensor doing it? Sorry if this has been covered before I've been searching everywhere and its hard to keep track of what I have found. This is my first Subaru, I'm more of a domestic guy my other car is a 62 Ford Galaxie. I know nothing about them other than I like the car enough to try and fix it. Here are a couple screenshots of what I got on the scanner. Edited December 23, 2015 by Cobrae Quote Link to comment Share on other sites More sharing options...
wtdash Posted December 23, 2015 Share Posted December 23, 2015 Assuming it's avl. swap the '03's O2 sensor...but really should get a new one....does NOT have to be OEM. Look for Denso brand on Amazon or similar. GL, TD Quote Link to comment Share on other sites More sharing options...
Cobrae Posted December 23, 2015 Author Share Posted December 23, 2015 I was thinking about swapping the 03 on as a temp deal just so I can drive it till I can get a new one. Defiantly going to get it online the local parts store quoted me $232 for the upstream sensor. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted December 23, 2015 Share Posted December 23, 2015 Does it have a MAF sensor? I would suspect that if it does. Front O2 sensor would be my next suspect. Quote Link to comment Share on other sites More sharing options...
wtdash Posted December 23, 2015 Share Posted December 23, 2015 (edited) No MAF on the '00-'04 Ej251, IIRC....just the MAP. Denso on Amazon - <$35 No MAF in/on the intake tube of this 2002 Subaru EXAMPLE: http://images.gtcarlot.com/pictures/60960101.jpg Edited December 23, 2015 by wtdash Quote Link to comment Share on other sites More sharing options...
Cobrae Posted December 23, 2015 Author Share Posted December 23, 2015 (edited) That was my first go to then I got looking at it as it had a CAI kit on it and I was like.... ooooook there is no MAF then I found the MAP sensor. I have since put an original intake on it though. The MAP sensor I got was used from a friend in unknown condition. Didn't run any better or worse so I assumed mine was ok. Or both could be dead lol. Edited December 23, 2015 by Cobrae Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted December 23, 2015 Share Posted December 23, 2015 I couldnt remember if Legacy had a MAF that year or not. I think the Forester may have for 99-01ish. Whenever you see fuel trim numbers maxed out all the way in one direction or the other, probably gonna be an O2 sensor problem. Can you do another screenshot at idle, and include TPS in your PID list. Quote Link to comment Share on other sites More sharing options...
Cobrae Posted December 23, 2015 Author Share Posted December 23, 2015 Will in a few got the laptop charging. Forgot and left it in the car all night. Didn't like the cold much. Quote Link to comment Share on other sites More sharing options...
logic23 Posted December 24, 2015 Share Posted December 24, 2015 Check the Knock sensor.. they will cause a scenario like this Quote Link to comment Share on other sites More sharing options...
Cobrae Posted December 24, 2015 Author Share Posted December 24, 2015 I actually changed the knock sensor also off the 03, forgot to mention that. Quote Link to comment Share on other sites More sharing options...
Bushwick Posted December 24, 2015 Share Posted December 24, 2015 It can be either up or downstream O2 sensor. They might not even throw a code either. My 99' Saab 9-3 had a similar issue some time back. Only codes it popped were for the O2 heating elements (both sensors). Car ran w/o issue for over a year, then started getting the random misfires. In my case, the after the car warmed up for roughly 5 minutes, going down the road it'd misfire. Then it'd eventually straighten out. Near the end, that got worse and would continue to cause the misfire. Last time I was running catless briefly and it back-fired with so much force it blew a new muffler apart at the seams! I 1st replaced the front O2, but misfire persisted. Replaced downstream O2 and problem cleared up and never returned. Upon close examination of downstream O2, the metal casing on the outside was cracked and rusted (where wiring loom enters sensor). Mind you, it never threw any codes other than the heater element. But even that shorting out can cause all sorts of issues. Try disconnecting one then both sensors and driving the car. Engine should go into limp mode as it can't detect either sensor. See if problem disappears. Quote Link to comment Share on other sites More sharing options...
Cobrae Posted December 25, 2015 Author Share Posted December 25, 2015 Ill try but as it sits right now the car is not drivable. Will only go at almost full throttle and thats just gonna break something or ruin the clutch. Any less and it bogs and stalls or bucks. That or you try to go a constant speed and just a slight move of the throttle to slow down = no throttle and it kills the engine or idles or god knows Quote Link to comment Share on other sites More sharing options...
Bushwick Posted December 25, 2015 Share Posted December 25, 2015 (edited) With sensors disconnected, engine should run in a closed loop. You'll get CEL, and MPG will suffer, but it should at least run, and should help rule out a sensor that's shorted internally and messing with the ECM. Ideally a multi-meter should help detect issues with O2 sensors, but it can be more difficult with intermittent issues. Just disconnecting them is a crude, but effective way to quickly rule out if an internal short is present. You could have a clogged cat too. The honeycomb can melt into a blob that resembles blown glass. Sometimes only part of the substrate melts, while a small section remains unaffected and allows some gases to exit. On light throttle/slow speeds, it might not be noticeable as the engine is still able to pass through the restriction. A vacuum gauge is paramount to troubleshooting a clogged exhaust if it is actually an issue. A cat can clog from overly lean and running too hot, which can occur from fuel additives to malfunctioning O2 sensors. If your exhaust is really sooty, that'd be a rich condition. Edited December 25, 2015 by Bushwick Quote Link to comment Share on other sites More sharing options...
Cobrae Posted December 25, 2015 Author Share Posted December 25, 2015 (edited) I dont think its a clogged cat just cause the car runs too good at wide open and when its not bucking it runs perfect at any throttle. Gonna go out and scan it again at idle and stuff real quick. It could be the cat I dunno but it just seems to run too good when it decides to. Just unhooked the front o2 and let it run for a bit. No change at all in how It runs. Edited December 25, 2015 by Cobrae Quote Link to comment Share on other sites More sharing options...
Cobrae Posted December 26, 2015 Author Share Posted December 26, 2015 Just got out from under the parts car, o2 on that thing was welded on with rust. Is a maine car with 200k afterall lol. That one posted up there will work on the upstream? Says its a downstream but Im guessing the sensors are the same just diff hookups. Quote Link to comment Share on other sites More sharing options...
wtdash Posted December 26, 2015 Share Posted December 26, 2015 Just got out from under the parts car, o2 on that thing was welded on with rust. Is a maine car with 200k afterall lol. That one posted up there will work on the upstream? Says its a downstream but Im guessing the sensors are the same just diff hookups. I'd find one specifically for UPstream. I neglected to spec which location. ???? Quote Link to comment Share on other sites More sharing options...
Cobrae Posted December 26, 2015 Author Share Posted December 26, 2015 Yeah im probably gonna order one when I can. Hopefully thats all it is. I like the car but there is no way I can afford to bring it to a shop around here lol. I know old cars these newer ones are way out of my league normally. Quote Link to comment Share on other sites More sharing options...
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