EricsLGT Posted October 31, 2021 Share Posted October 31, 2021 I have a bone stock 08 LGT. I bought it 3 weeks ago from the original owner. Out has 217k miles and engine was rebuilt about 20k ago. Stock rebuild. The owner hasn't driven it much in the last year or two. Not sure on those details. After I bought it I noticed some bucking under hard accel. but thought I'd run a fresh tank through it to see if it would clear it up. It seemed to take care of that issue. The only other drivability issue I have had is engine big if I snap the throttle, like giving it a blip before engaging the clutch or rev matching. After putting about 400 miles on it, I got a check engine light. P0171, lean. The last thing I did before getting the code was to double check that I put the sorbic back together correctly after checking the filter. I'm pretty sure it's sealed up tight. After looking on forms I got a Bluetooth OBD2 scanner and have been using an app to monitor fuel trims and other info. Yesterday, they seemed normal at idle and then fluctuated a lot while driving. I'll add the screenshots. Today, I checked fuel pressure and it seemed okay. Around 30psi at idle and increased to like 40 under accel. Are those numbers okay? I looked for vacuum leaks though I feel like those would be effecting the idle more than they were. I pulled the tmic off to check the pcv and found the pipe from throttle body to intercooler was loose at throttle body. I put it all back together and proceeded to relearn the idle. It was pretty wonky when I first started it before doing the idle relearn, so I was hopeful it was fixed. First start after reconnecting the battery it would fit and stall. Did that the times before I intervened and gave it gas. After doing the relearn, CEL was back on and STFT was at 25%, LT at 0 and it was idling a little rough still. I drove it a bit and both ST and LT were all over. My first time jumping into stuff like this... Any help would be great! Attached screenshots are at different speeds and from before tightening hose and resetting computer. Link to comment Share on other sites More sharing options...
heartless Posted October 31, 2021 Share Posted October 31, 2021 2008 will be a "drive by wire" throttle pedal - meaning no actual cable between pedal and engine.. all electronic.. and with that kind of mileage, would not surprise me if it needed a new pedal assembly.. the sweep that tells the ECU where the pedal is just wears out. had to replace the one on the other half's 06 LL Bean Outback.. made a BIG difference in responsiveness. 1 1 Link to comment Share on other sites More sharing options...
idosubaru Posted October 31, 2021 Share Posted October 31, 2021 Find any other vacuum leaks. Check for any exhaust leaks, upstream of sensors. Those items are directly related to engine removal and installs which yours needed if it was “rebuilt” Test the O2 sensor and catalytic converter. Those could be impacted by issues requiring a “rebuild”. Too much fuel, oil or coolant entering the exhaust. You might want to watch what the O2 sensors are doing while watching STFT and LTFT but I’m not well experienced in interpreting the results. But I’d be curious what it looks like. 1 Link to comment Share on other sites More sharing options...
idosubaru Posted October 31, 2021 Share Posted October 31, 2021 Some Subarus in the last 10-15 years have had auto trans and ECU software updates too - I’d check with them and see if your VIN has been all updated. 1 Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted October 31, 2021 Share Posted October 31, 2021 usually, the pedal assembly failure throws a code, P21?? something......? Link to comment Share on other sites More sharing options...
heartless Posted November 1, 2021 Share Posted November 1, 2021 5 hours ago, 1 Lucky Texan said: usually, the pedal assembly failure throws a code, P21?? something......? maybe eventually, but it did not right away on the 06... took several months for it to finally throw a code. In the meantime, we were scratching our heads trying to figure out what was going on with it. Sometimes it would be fine, others it wasnt.. 1 Link to comment Share on other sites More sharing options...
EricsLGT Posted November 1, 2021 Author Share Posted November 1, 2021 Alright, so I went looking for vacuum leaks again and pulled the intercooler of to make sure I got everything plugged back in correctly. I found that while I was fiddling with the pcv valve yesterday, I had accidently unhooked the line that runs from the bpv on the intercooler to the ...? I can't remember now what it connects to. Anyway, I hooked that up, looked around for anything else I might have missed, and put it all back together. The idle and the fuel trims at idle all went back to normal after that. It seemed to drive okay, but the fuel trims were still bouncing around a lot while driving. I plan to clear the code and drive some more, watching the fuel trims. So, if the hose to the throttle body was a little loose, would that be enough to throw the lean code after about 400 miles? Nothing has given me the impression that the pedal assembly could be malfunctioning. What kind of symptoms did you have with that? I have not noticed any exhaust leaks, but I will look a little better next time. I will also start monitoring 02 sensor voltage and consult the internet on what that should look like. As for testing the cats... I don't think I'm equipped to do that. Link to comment Share on other sites More sharing options...
heartless Posted November 1, 2021 Share Posted November 1, 2021 10 hours ago, EricsLGT said: Nothing has given me the impression that the pedal assembly could be malfunctioning. What kind of symptoms did you have with that? it has been a while since we had the problem... but if i recall, just a general lack of/slow response to throttle input. possibly a bit of stuttering as well in certain positions. Sounds like you may have found the problem with yours.. hope so anyway. Link to comment Share on other sites More sharing options...
idosubaru Posted November 1, 2021 Share Posted November 1, 2021 12 hours ago, EricsLGT said: Alright, so I went looking for vacuum leaks again and pulled the intercooler of to make sure I got everything plugged back in correctly. I found that while I was fiddling with the pcv valve yesterday, I had accidently unhooked the line that runs from the bpv on the intercooler to the ...? I can't remember now what it connects to. Anyway, I hooked that up, looked around for anything else I might have missed, and put it all back together. The idle and the fuel trims at idle all went back to normal after that. It seemed to drive okay, but the fuel trims were still bouncing around a lot while driving. I plan to clear the code and drive some more, watching the fuel trims. So, if the hose to the throttle body was a little loose, would that be enough to throw the lean code after about 400 miles? Nothing has given me the impression that the pedal assembly could be malfunctioning. What kind of symptoms did you have with that? I have not noticed any exhaust leaks, but I will look a little better next time. I will also start monitoring 02 sensor voltage and consult the internet on what that should look like. As for testing the cats... I don't think I'm equipped to do that. Yes loose intake results in unmetered air. Make sure again there’s no intake or vacuum leaks. Are O2 sensors original with 200,000 miles? 1 Link to comment Share on other sites More sharing options...
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