Dalee1104 Posted June 27, 2019 Share Posted June 27, 2019 Hello all, I've been around these forums awhile with my previous cars and have recently secured a new to me 02 outback. It's the base model and has 260k miles. Picked it up for 1000 bucks and the head gaskets, timing belt, and clutch have all been replaced fairly recently which is why I decided to go through with the purchase. Now I'm getting a little weary. Driving it for about a month and keeping the rpms low it developed a really bad exhuast leak which I thought was the source of a p0171 code I pulled. Saved up some and just installed the uel headers and had the hole system welded up all nicely. Now that the car is nice and quiet I've been able to hear some slight clackity noises upon start up and also higher rpms. That being said I've been keeping up on the oil and maintenance and keep it below 3k The reason I'm posting here is because I've ran into an issue that kinda stumped me. I checked the codes for safe measure and plugged in my torque pro app and pulled a pending p0420, an active p01507, and a still active p0171. I was checking all my screens on torque and everything seems okay intake wise, I checked with starting fluid for a vacuum leak. Only thing that really scares me is the afr is pegged at 22. With the afr pegged extremely lean the short term fuel trim is also clear up to a 35% at idle. With the afr pegged so damn high I dont want to drive it because it's an old tired engine and running max lean is asking for it to blow I feel like. I'm just kinda looking for help on what this could be? What controls the afr? Is it the afr sensor solely? And if so how do I know if mine is bad? The car has a semi hesitant idle but nothing really too bad. How can I fix this car for a reliable daily driver Link to comment Share on other sites More sharing options...
RumbleRumble Posted June 28, 2019 Share Posted June 28, 2019 p01507 is idle air control and p0171 is a lean code. make sure you don't have a exhaust leak before the cat. The front 02 sensor is pretty easy to replace if it doesn't look new. Link to comment Share on other sites More sharing options...
Dalee1104 Posted June 28, 2019 Author Share Posted June 28, 2019 I did have an absolutely massive exhaust leak before the cat but after installing the headers I had the shop replace all the gaskets and seal her up. The p0171 may be residual then as I didnt clear the codes yes but being that I have no more leaks, I'm curious as to why the car was intermittently lean while logging Link to comment Share on other sites More sharing options...
Max Capacity Posted June 28, 2019 Share Posted June 28, 2019 The front O2 sensor is responsible for meting fuel flow. Check the wires going to it. Investigate that IAC too. That sound, check the idler pulley's for the drive belts. 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...
twisty Posted June 28, 2019 Share Posted June 28, 2019 that p0420 could be leftover from the exhaust as well, id say clear them and see what comes back after a bit of driving. the sounds you are now hearing, are they seeming to be internal? Link to comment Share on other sites More sharing options...
Dalee1104 Posted June 28, 2019 Author Share Posted June 28, 2019 I'll have to pull the iacv and clean or replace it. Likely replace the O2 sensors as well for safe measure. And honestly that's what I'm worried about twisty, I've heard what rod knock sounds like in a few or my buddies subarus who forgot to check they're oil but the only difference is on this outback its much quieter, but still a deeper pitch than valves. On top of that its only on start up and only above 3k rpms. Once shes running if I keep her around or below 3500 rpms it seems fine, havent really hammered it out of fear I'm on borrowed time with this engine. What does this sound like to you guys? Worn crank bearings maybe? If I run heavy oil, possibly some Lucas if that helps, and keep her low rpms, do you guys think she should last a bit longer? On a side note I have noticed I'm getting a decent amount of smoke coming out of the tailpipe when the engine load is increased like up a hill or something. I'm guessing worn rings causing a bit of oil blow by? Smoke is blackish in color Link to comment Share on other sites More sharing options...
doublechaz Posted June 29, 2019 Share Posted June 29, 2019 (edited) Black smoke is un-burned fuel. Blue would be oil. White would be steam from coolant. I'd say with the black smoke that you are not actually lean but rich. An exhaust leak ahead of the front O2 makes the ECU think you are lean so it puts more fuel in. This fuel doesn't actually help with the air pulled into that leak after the combustion event, so it puts more fuel in. You end up with max positive fuel trim which triggers a lean code. Eventually you get carbon clogged cats and washed cylinders. BTW the exhaust leak that can let air in like this sounds like a lifter tapping. I've done this before on my car. I bolted on a lot of parts before I learned enough to understand the situation. If you can drive the car up on ramps in the front and get under there with it's running, try to see if the sound is coming from the manifold to head connection. I don't know what headers you got, but the ones I got are badly warped where they bolt to the head. There is no hope of them sealing until I figure out how to bend them straight and even. Until then I'm on OE Y-pipe. P.S. Every time I have my header off, I use a little bit of RTV ultra copper on both sides of the gasket. It is very common to have a leak there with most brands of gasket. Edited June 29, 2019 by doublechaz Link to comment Share on other sites More sharing options...
Dalee1104 Posted June 29, 2019 Author Share Posted June 29, 2019 Okay I'll check that later today. Do you guys run any Lucas or anything like that on your older engines? Opposed to it for any reasons? Link to comment Share on other sites More sharing options...
doublechaz Posted June 29, 2019 Share Posted June 29, 2019 At 300k I'm running a mix of 10-40 and 20-50 especially when ambient is above 100. It helps keep the oil pressure up at idle for me (I have an actual guage), but the down side is it burns more. Seems that the oil is too thick and the rings can't scrape enough off the cylinder walls. (10-40 is what my original owner's manual calls for at my temperature range.) Link to comment Share on other sites More sharing options...
Dalee1104 Posted June 30, 2019 Author Share Posted June 30, 2019 Okay I'll probably run that as well then. Checked the gaskets out and there is a slight leak, go figure, but not the same sound as I'm hearing that has me worried. Still basically above 3k get a pretty rowdy metallic sound so I'm thinking internal. Might just try and keep my rpms as low as absolute possible and see how long she'll last Link to comment Share on other sites More sharing options...
doublechaz Posted June 30, 2019 Share Posted June 30, 2019 Can you isolate what area the sound is coming from? Could be the timing belt tensioner. If it really is rod knock, it won't be long before you know. Link to comment Share on other sites More sharing options...
Dalee1104 Posted July 1, 2019 Author Share Posted July 1, 2019 I suppose that is true. I can definitely try. It know it always sounds louder on the drivers side by the wheel well. Sort of underneath the engine gets decently loud. I've heard people mention piston slap and rod knock, what's the difference? Is whatever I'm hearing possibly piston slap? Link to comment Share on other sites More sharing options...
twisty Posted July 1, 2019 Share Posted July 1, 2019 had a friend with a 98 or so forester that had the same thing going on, sounded like a knock at higher RPMs. we put some lucas in it and seemed to quiet it down pretty well, but it eventually failed and spun a bearing or two. i think she got about 3 or 4 months out of that engine after that. Link to comment Share on other sites More sharing options...
Dalee1104 Posted July 2, 2019 Author Share Posted July 2, 2019 Okay so Lucas it is and hope for the best lol might just start saving to find a junk yard ej251 to just drop in it when this one goes Link to comment Share on other sites More sharing options...
doublechaz Posted July 3, 2019 Share Posted July 3, 2019 (edited) Rod knock is when the bearing in the big end of the rod has failed so there is room for the rod to bang back and forth as the piston changes direction. Piston slap is when the skirt of the piston doesn't fit the bore and slaps into it as the side loads change during crank rotation. Could be piston skirt wear or bore wear. I'm hoping for exhaust still if it is definitely on one side and louder below than above. I suppose with a 251 you have valve lash buckets for solid lifter adjustment. Could be an exhaust valve clicking. Hard to describe but... Injectors tick Valves click exhausts pit Pistons chuck rods clack timing belt tensioners clunk I forgot to mention before. Get about three feet of hose about 1 inch diameter. One end to the ear sealed up with your hand in a fist around the end of the hose. Probe around in the engine bay with the other end. It helps isolate where noises are coming from. It takes a fairly long time to slowly search around all over and carefully compare the sounds. You'll need a fairly quiet place to do this. At my house I have to wait until everyone is stapled to their couch or asleep as any other time my street is a lot like the Indianapolis Speedway. Edited July 3, 2019 by doublechaz Link to comment Share on other sites More sharing options...
RumbleRumble Posted July 5, 2019 Share Posted July 5, 2019 rod knock noise goes up and down with the revs. piston slap is when revving and not on decel. Rod knock sounds horrible and piston slap sounds "questionable" Link to comment Share on other sites More sharing options...
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