CT10LGT

Well, just figured this problem out. For reference, I pressure tested the entire intake, checked the fuel press (when running and when engine off to see if it bled down quick), replaced the upstream O2 (even though it appeared to be reading correctly). As a last resort I replaced the injectors (in case one was not always closing) and replaced the exhaust OCV (because I had a spare set and it was the solution to someone elses similar but not identical problem). Nothing helped. STFT droped as soon as it went closed loop and then eventually pulled the LTFT to -25 and then you get the CEL again. So I started pulling sensors and actually Ohm'ing them out. Found the intake air temp portion of the MAF was showing "open" all the time. Bought a new one ($80) from RA, swapped it in, problem solved. So, the morel of the story is don't always believe the OBD2 data. In my case Torque was reporting the intake temp was "normal" however Torque must be mapping the "intake temp" to some other temp sensor because the one the ECU uses, the one built into the MAF was open. Open temp sensor means "as cold as you can measure" thus the ECU thought, damn it cold out, better squirt lots of gas in this dense air, then the O2 sensor goes, whoa, there is too much gas, start trimming it back, right up to the point where LTFT is at -25 and it trips the CEL. All while Torque is reporting all sensors reading "normal" values. Good news is it's got nice new injectors now, should be good for another 100K miles.

Well, learned today that the upstream O2 sensor is wideband so you really care about the current, not voltage. 4.0V is normal, current at +/- .500 mA when blipping the throttle is what I'm seeing, which is OK. DrD, the MAF checked out clean but I sprayed it again just to be sure. It appears to increase properly when throttle is opened. After driving (warm) it's now reading closer to 3.2-3.5g/s when idling vs "sitting in garage" warm, I think this is OK. I attempted a pressure test by blocking the intake after the airfilter and putting a couple of PSI in the bypass hose (oil filler cap off), losing air somewhere so I disconnected the intercooler, capped it there an reran the test. No leaks from there thru intake so I must have a leak either in the intercooler, uppipe, downpipe or fittings. Will attempt to pressure test intercooler by itself as the very quiet muffled leak sounds like it might be coming from there. Leak sounds pretty small, can't believe this is what's causing the STFT to go -22 as soon as it goes OL. My gut tells me there's a bigger problem. Is it common for the FPR on these to go bad? For $95 might just have to replace it as I don't have a good way to measure fuel pressure. Anyone have any other ideas? Is there any way I can test for a stuck or sticky injector. Once I get it back together I'll post a picture of my Torque screen, see if anything jumps out to those with more knowledge of what "normal" values are for this car. Thanks

Hello, have a 2010 Legacy GT, just started throwing a P0172 code. Plugged in my OBD2 reader and checked the LTFT, STFT, MAF and O2 values. Sure enough LTFT was pegged at minimum, STFT jumping around 0.0 +/- 5.0 but lambda was at 1.00. MAF appears to be high to me at 4-5g/s, thought it should be closer to 2.5 at idle. The odd one to me is the upstream O2 is mostly at 4.0V but occasionally drops to 3.9, shouldn't this only go between 0 and 1V? So I replaced it with a new O2 and it reads the same, pegged at 4.0 most of the time. If I pull the connector off and measure across the pins (non-heater side) I don't get 4V, mostly it's at 0V but does occasionally jump around under 1V. The downstream O2 sensor looks normal as it's at .78V. Any ideas what is going on? Can someone tell me what values I should be reading for this car when it's warmed up and idling? Would like to have values at idle for MAF (g/s), O2S1(V), O2S2 (V), intake (PSI) and any others that you deem important that I'm missing. Thanks

Nope, did not swap the cam sprockets (used JDM) although we did need to remove the left set to replace the rear timing cover. Bought the special tools to hold the other cams in place. Did not do anything with the valve covers, didn't dig down that deep, just swapped the intakes over, reused the old gaskets. Wouldn't worry about shipping next time, all the damage was done at JDM engine zone, wasn't much left to break other than the turbo. Shipping wasn't all that expensive.

Well we (son and I) successfully did it. Bought an engine from the JDM Engine Zone in NJ ($1300), drove and picked it up in person. Checked it out while still attached to the trans. Looked good, had same turbo (my main concern). OK'd it but then walked away while they removed the trans (I didn't need it and it was auto anyway). Mistake, they must have used a forklift to separate the two. Many bent broken parts (they don't guarantee anything but the long block, everything else is "free"). Didn't notice until I got it home that they put a hole in the left rear timing cover (cost me an extra day and some custom tooling to pull the cam pullies off to replace it). Thought I'd have lots of "spare" parts but found they broke most of them in the process (coil packs, etc.). Ended up swapping the old intake over, the wiring harness on the new looks like it would work but the main disconnect plugs were in a different location and would have taken more work to untangle it all. The gas lines have different ends and would not directly connect US connectors. The auto trans JDM engine didn't have an oil cooler (warmer?) and mine was all rusted out so just deleted it. There was an extra coolant line that I removed and plugged. The water pump that came in my new timing parts kit would fit but had the outlet on an angle (think I ordered the wrong kit so not a JDM engine issue) so reused the JDM one. The JDM right rear timing cover didn't have timing belt "anti-jump off" bracket, didn't realize until I had the new timing chain and components in and was putting the front cover back on. Wasn't going to undo all that so just ignored it, apparently auto trans engines don't have/need it. Had to swap what I think was the temp sender from old engine over only because of the connector (fast on tab vs screw down) because I didn't want to cut into the wiring. Engine started right up and runs fine, no CELs. Did clutch at the same time but reused flywheel, mistake, it chatters, will repull engine and put in a new one.

Following as I'm just about to do the same. Hopefully someone has some useful advice other than "go get a service manual". Good luck.

Thanks, looks like I've got to cut the studs off then replace them on the forward cat + 2 new nuts before reinstalling engine. Can get the grinder in to get the easier one, going to get a pneumatic saw to get the other as my saws-all is just too big. Guess I should splurge on a service manual but am 90% thru yanking this thing, but do appreciate the info on getting me through the remaining 10%.

Ok, newbie here, just bought a '10 LGT with a bad engine. Son and I are attempting to remove to get it repaired. Followed a bunch of YouTube videos but most are for pre '10 LGT or non-turbo '10 and later Legacys so none seem to show where I should be disconnecting the exhaust. Much rust in exhaust area, lower heat shield just fell off when I touched it. I tried to remove nuts (QTY: 2) that attach long exhaust pipe to larger diameter short curved tube, nuts are now rusty cylinders, no grip. They appear to be on threaded studs that have no features to remove them. Might be able to get to QTY:6 nuts that attach exhaust manifolds to block but this would seem to not quite accomplish full separation. Can someone who has worked on this version LGT provide some much needed guidance. I might be able to cut the QTY: 2 rusted nuts off (die grinder on one, saws-all on the other, is this my best bet?? Thanks