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What did we do wrong? Detonation? She knocks :(

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Hello all, I am hoping to get some insight as to what might have happened to my engine which now knocks. Teardown will hopefully start this week so that should tell us what is damaged, but may not tell us why...


2005 Legacy GT wagon 5mt. Relatively stock with some bolt ons (perrin downpipe and intercooler, LW flywheel, exhaust), as well as an accessport.


I bought the car in 2018 with about 145k. I work in service up front at a dealership and have seen firsthand the troubles these motors can have with poor maintenance and wanted to get ahead of it. Had the headgaskets replaced, valves adjust/shimmed, new plugs, all timing components and waterpump replaced, because I had no records of any of these services. Also had clutch flywheel and such replaced with a more standard weight but still single mass kit, and had him put some more bolt ons like a turbo inlet and recirc valve.


The work was done by one of our technicians on the side and I had asked for a very thorough job and feel like I got a bit of a rush job. I think he did do the shims and gaskets and all of that correctly, but once he got passed that and the long block was together, I think he wanted the money more than he wanted to do quality work. As things went back together from there, there was a lot that should have gotten replaced that did not. Namely rock hard vaccum lines, rock hard turbo drain tube, and some pretty minor stuff that would be easy while it was apart. Whatever.


The car ran well enough and was given back to me. I had to replace the turbo drain tube which sucked while the car was back together. Mostly though I did not have any issues. I did at some point have a boost leak and had to replace the notorious intercooler coupler. That was fine. Somewhere after this I ran into a target boost problem where I would intermittently hit only about 10 psi and so after some reading here I replaced my boost control solenoid and cleaned the MAF and it worked well again, hitting about 18psi (not sure which fixed it as I did them at the same time, but I would bet on the MAF). In the process, I had smoke tested the car and found significant vaccuum leaks. Significant...


Drove the car as is against my better judgement for a short time but it was not my only car so it didn't end up with too many miles in this state. Still, we can fastforward to this last couple of weeks. Car was still running well and hitting peak boost, but it was time to fix the vaccum leaks. Have about 150k on it now. Another technician and I pulled the intake and found all of the stuff that really should have been replaced the first time around, but whatever, we had most of the vacuum lines on hand, a few more got ordered and replaced a bunch of rotten PCV lines while we were at it. Put it back together, started up just fine. No issues.


Drove the car home that night to burn off some powersteering fluid and coolant that had been spilled. Car was running great, cruise control even was a lot smoother at it had a bit of a lope before, but saw I was only getting about 11-12 psi. Drove it back to the shop and parked it so I could look at it again the next day. Next day roles around and I figure I may have a vacuum/boost leak so my plan is to start with a smoke test. Simple. No leaks detected so I am pretty excited about that, but have no clue why my boost was not right. I'll let the tech look at it the next night and figure that out. Start the car and get a light pinging so I immediately shut it down. Thought maybe I had just heard another tech who was still working in the shop, but I looked everything over once more, it all looked in place, not that I had taken anything apart to smoke test anyway. Start it again and my worst nightmare has been realized. Full blown knocker.


Looked at it the other night with the second tech and could not find anything out of place. Cyl 3 was the issue looking at roughness monitor. Swapped coils and still the same issue. We are a bit stumped at this point as to what might have happened. The only thing I can think is that I had detonation (the pinging) and then suffered ringland failure (the knock). It does not seem like an oiling issue or bearing failure, although the noise was hard to pinpoint so that is possible. If I am correct then my cylinder wall on #3 is probably jacked, so I've already started looking at reman short blocks, but I still dont know what happened as we did not have a chance to solve the underboost issue. I dont know if it leaned out or just missed and detonated or what... Our borescope is broken so I am just going to have him take the heads off and inspect for damage. My biggest concern is that we put a new shortblock in and it suffers the same fate...


Thanks for reading my long winded story. Any advice would be greatly appreciated. I'm sure there is not much here that can be diagnosed over a forum, but I needed to vent and I am hoping for some sort of magical answer. I am a very sad man

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That blows, but at least you have access to the expertise needed to get it fixed up. Can you clarify what you mean by light pinging? Could it be valvetrain noise or no?


Sounds like you guys are a Subaru dealership and have access to an SSM tool to see what kind of fine learned knock correction and ignition advance multiplier adjustments may have been stored. That would at least give you some indication whether or not it was detonating (and how severely based on load range and how much timing was pulled) while you drove it. Learned fuel trims would also give you some idea of how bad the vacuum leak really was. All of that is if the battery hasn't been disconnected and the ECU hasn't been reset.


You can buy a borescope good enough to do what you need on Amazon for $20 or less - I'd start with that rather than pulling the heads. At that point I'd make the call whether it's worth doing compression/leakdown or just save the effort and pull the motor.


My .02

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I only work here for another week before I move, lol. It was really bad timing. The battery was disconnected when we took the intake manifold off, so I wont see how bad the old vacuum leaks were, and as far as I saw with the smoke test there are no vacuum leaks currently. But yes we do need to spend more time with the scan tool on it.


EDIT: My foreman tells me the only way I would have data is if the Check Engine Light set and saved freeze frame data. The CEL did not set, surely because of the accessport tune.

Edited by SageAbkatsorLocked
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A compression test and/or leak down test would be the next step before pulling the heads.


Was the injector checked on #3 ?


Are the coil connectors clean and tight ?


Have you zip tied the vacuum lines ?

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

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Have not checked injectors. Not a bad thought.


So we thought maybe the coil connector could be an issue because we made a repair to that connector during the intake swap. It was broken and had to be zip tied to the coil from the original repair, so we swapped a connector (just the plastic piece, pulled the pins from the original so it’s not a splice or anything) from an old harness in the back and my technician thought he swapped the wires to the wrong pin but wiring diagrams showed that everything looked right. We swapped coil packs on the passenger side and the dead cyl was still #3. I don’t know that we ruled out 100% the connector that was repaired, but I think we safely ruled out the coil itself.


The part that doesn’t add up with it being a coil or connector issue though, is that I drove the car home and back. No missing, no noise. Butter smooth, just not full boost.


Vacuum lines are all tight.


Also another datapoint for consideration. When I prime the engine (crank w/ WOT) I can hear a clack noise. Not every turn of the engine produces the noise though. I hate to give myself any false hope, but you’re right that more testing must be done. I have pretty much just assumed the worst based on the noise. I don’t see how something is not terribly damaged internally. Sounds like either a rod knocking or a piece of piston slamming around in the cyl.

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FWIW, here's my #3 connector, its been zip tied since the first spark plug change at 60,000 miles, car now has 276,800 miles.




May be want to pull the timing belt covers and make sure the pulleys at all in great shape.


Make sure the crank pulley is tight and in good shape, some have been known to separate.

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

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All timing components were replaced 5k miles ago, with factory parts. That’s a good thought though too, you mean the cogged pulley(crank sprocket) under the harmonic balancer or the harmonic balancer itself? I feel like I’d have more than one cyl off if that was the case though
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when you had the car apart the first time by that naughty tech, did he pull the shortblock apart?


were there signs of abuse when you bought the car?


I was that guy.... I was chasing the dragon changing everything but ultimately it was internal, I pulled my block apart to clean and inspect my pistons, they looked fine at first but after they were cleaned I noticed the hairline cracks in the ringlands for 2 pistons then it just fell off in my hand.... These pistons are shit and sneaky.....veeeeeeeeeeeeeeery sneaky.... he shoulda pulled the pistons at least when he had the heads off... this just screams lazy, especially if you asked for thorough... from a dealership tech no less.... smh


These shortblocks suck ass.... and are far from bulletproof. ringland failure is a common issue, to not even inspect something so crucial.... what else did he overlook!


You really should do a compression/leakdown and scope it before even wasting your time!


Also what about the condition of the turbo? Is it still the original? was it properly inspected or rebuilt? Thats a lot of miles for these turbos, especially if it was beaten on.


Have you dropped the oil pan or inspected/tested the oil?


This tech rebuilt a complete engine with old crusty hoses.... these hoses are like 5-10 dollars even cheaper if ur getting it at cost, why would he skimp, the parts are right there in the dealership, no? I can understand the coolant lines, but not changing the intake lines.... that's asking for trouble, i wouldn't trust anything else they did, where theres smoke theres fire....most times...


Also the fuel injectors, were those cleaned/serviced/changed?? Try swapping them around to see if the problem moves.

Edited by Tehnation
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Shouldn't be any issue dropping an engine from an auto in there, right? A friend may have found a part out, but we don't know the details yet... I much prefer to put something fresh in there but maybe drop this in while we build the other over time...
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aren't u working at a subaru dealership??? just get a new shortblock at cost.... your crazy... with the resources you have why bother with used, new shortblock , put it back together and be done...


did you figure out what happened with the current motor?

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employees don’t get parts at cost. With my employee discount, which is just a small mark up, a shortblock is just over $1800. I talked to my Parts manager and he was not sure how Heuberger Subaru is able to offer such discounted prices.


I do know that the more parts a dealer’s parts department sells in a year the larger the break they get on those parts (but only up to a point as far as I am aware), so my guess is Heuberger is a much larger dealer than we are but may also have very small mark ups and bank on high sales volume. Regardless my being at the dealership doesn’t do a ton for me in the way of getting a shortblock. If I went OEM I would just get one online.


With that said, I also just had my last day yesterday so... there’s that.


I have scrapped the idea of putting a used one in. Doesn’t make sense.


As far as what happened I only sort of know. Last night we stuck a borescope in and didn’t find much in the way of damage, but the gap on the plug had been reduced to almost nothing even though there was no evidence or witness marks that something had impacted it. Swapped in a new plug just out of curiosity and my misfire was gone, obviously still knocked though.


Cylinder heads came off today and the ringland failed on cyl 3 so I am assuming a piece of the piston impacted the plug and then exited via exhaust valve. There is no scoring on the cyl wall, but the head got a little roughed up. It still doesn’t answer all my questions but it does confirm that I need to build it all fresh. Hoping my cyl head can be saved.


Ordered OSVs, oil cooler, oil pump, engine gasket kit, oil pressure switch, and new banjo bolts and my parts manager said he would honor my employee discount.


Planning on a Sunwest short block. A place not too far from me will do the turbo rebuild. Need to find a place for the cyl head machine work...

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how much for the sunwest shortblock? does it have better internals? did your old job have a local machine shop to outsource to? maybe rebuild that block with some forged pistons and rods and get the block rebuilt.


before you pull the trigger you should take a long look at end your goals etc. doing shit twice is painful and expensive. once some people start they can't stop..... here i am 2 years later lol ...


here's how my engine rebuild broke down


So I ended up getting :


BC Stage 3 Cams BC0622 $650

BC Springs BC0600 $215

Manley Turbo Tuff Extreme Duty Pistons 632800CE-4 99.50 -17cc 8.5cr $650

Manley H-Tuff Rods 15024-4 $275

ARP Head Stud Kit 260-4701 $185

Subaru STi 11mm 15010AA360 Oil Pump $130

Subaru 10105AA720 Engine Gasket Kit $235

Cost to rebuild longblock, includes hot tank and 10k rpm balance, with King Bearings $1600 and whatever extra if they need to readjust the heads after assembling longblock.

Total $3940


Essentially it was $1k to rebuild the shortblock and $300 per head, if I were to get it separate, so might as well have them do it all for 1600! I ended up with a good deal and they tossed in the install of the oil pump as well.


So lets see 650+275+1000= $1925 vs spending $1700-$1900 for a new shortblock, I was able to build a nice new block with much better goodies! By doing a complete tear down I saved a lot on rebuild costs.



Final cost to rebuild longblock, includes hot tank and 10k rpm balance, with King Bearings $1815

New Total $4155

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Deck plate honed, hyper eutectic pistons, king bearing, OEM crank


We do have a machine shop we use. They do good work, but I may look for someone who more-so specializes in Subaru to do the head work. Worst case I know this shop can do it and they’ve always done good work before.


End goals are just stock+ with reliability as the primary focus. The other goal is to get the car back on the road. I can’t let it sit for 2 years at a shop I no longer work for.


In regards to your build, what about the oil cooler, OSVs, and turbo? What started you down the rabbit hole? Were you preemptive in your build or did you start because the last one failed?

Edited by SageAbkatsor
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preemptive, i have another car so this has been sitting in my driveway for a while....i was trying to tune it but never could find where the issue was, eventually realized it was probably the valves so I just tore it apart to make a better assessment, found out some of my pistons were shot, but everything else was fine, so I decided to rebuild it rather than get a new shortblock. I was able to rebuild the shortblock for around 2k with forged pistons and rods capable of 500+hp i would guess. ocvs and oil cooler I changed before while chasing this dragon trying to get it tuned...i am using a bnr 20g billet turbo... i have a thread going on here somewhere with more details...
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......the gap on the plug had been reduced to almost nothing even though there was no evidence or witness marks that something had impacted it. Swapped in a new plug just out of curiosity and my misfire was gone, obviously still knocked though.


Cylinder heads came off today and the ringland failed on cyl 3 so I am assuming a piece of the piston impacted the plug and then exited via exhaust valve.



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Hi guys, I am trying to confirm the correct ECU part number for a 2009 2.5i non turbo Subaru legacy with push button start system.


First off, you’re kinda hijacking this thread... I feel like there was a better place to post that question.


Second, a 2009 with a push button? I could most certainly be wrong but I don’t think that was a factory option. If you had a VIN I could give you better info as I do still have access to Subaru’s EPC for another day or two... The EPC doesn’t even list the special edition as having push button start, nor the limited.


Third, why do you need an ECM part number/why do you need an ECM? What gremlins are you chasing? Maybe it has to do with your aftermarket push button start?


Finally, 22611AN00C, 22611AN00D, 22611AN02C, and 22611AN02D are all listed for the automatic (4EAT) vehicles and 22611AM99B, 22611AM99C, 22611AN01B, and 22611AN01C are all listed for the manual (5MT) vehicles. Subaru calls this part the Unit Assembly - E.G.I. Control.


Part numbers 22611AN00C and 22611AN00D are superseded by 22611AN00E and there are 12 left in the country. Part numbers 22611AN02C and 22611AN02D are superseded by 22611BC05A and there are 24 left in the country. Part numbers 22611AM99B and 22611AM99C are superseded by 22611AM99D and there are 5 left in the country. Part numbers 22611AN01B and 22611AN01C are superseded by 22611BC04A and there are 3 left in the country.


There are a few other part numbers that were in the supersession list but I only included the ones listed in the EPC and the latest supersessions for the sake of simplicity. If you are looking for a used one you may find other part numbers that could work if they were in between the original part number and the final supersession.


The primary difference between any of the superseded parts and the latest supersession will be the software loaded onto it. A dealer scan tool’s flashwrite program should be able to take an old ECM and update it to the current software version which will actually tell the computer it has the new part number. Usually these updates provide some level of improvement to vehicle performance (not go fast performance but reliability or quality of life improvements) or emission control updates.


Good luck...

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1200 isn't bad at all! do these people have a website?? do they have options for a 2618 or 4032 forged ..... damn 1200 isn't bad at all. do they require a core deposit? that would be the swing factor 1200 + core ehhhh , 1200 without core thats an awesome deal.


any decent machine shop can rebuild the heads or block, it's not any kind of special technology. Its crazy sometimes how people really overestimate these engines, making them seem like some mystical magical creature, this engine design is like 20+ years old now, everyones seen one.... nothing to see here keep it moving lol

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I feel like every machine shop specializes in Subarus :lol: I'd be scared of a machine shop that says they dont work on many Subaru blocks.



On a side note, that's messed up they dont give parts at cost.


we are in the northeast and we see all seasons, snow, sand rain and sun, so subarus are everywhere, by now all machine shops should have adequate experience with them...


thats what i was thinking.... when i get parts from my local stealership, they charge me damn near cost because they make the money on service, not so much parts. They will say it costs 10 dollars then when I pay its like 6 or 7 bucks... they just knock it down on their own, to think they wouldn't for an employee....

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