birkhoff

Can you remind us: Cylinder 2 is your misfire cylinder? Something definitely is up with Cyl 2. If it is fuel, you don't want to leave it like that very long. The lube oil will be washed off the cylinder walls and you'll have sealing problems over the medium run. If it is oil, then lube oil is getting past the rings, diluting the fuel charge and possibly causing misfires in the first place. If it is fuel AND oil (as you suspect) then kind of like the first scenario except this has been going on for a while. I would run it for a couple of days. Bring it into the garage hot with minimal idling, pull the #2 plug and confirm that things really do look like that. If they do, well, . . . cross that bridge when you get to it.

Great pictures! Sometimes you can resize the rod big ends, but that one is toast. Better to source a replacement. I'd send all of them (3 plus replacement) to the machine shop and have them resized when you get the bores reconditioned. Mains do look good, but again, the crank is a goner. Don't even think about turning it down for oversize bearings. With the tight tolerances you need to hit, it is not uncommon to have to mix and match bearing shells. If you start with a new crank and with the mains looking that good, you may get away with a single set of STD size bearings. Get your pistons, take the case halves, pistons and rods into the machine shop and let them do their schtick. You probably just need a light hone and replace like with like on the pistons. If you want to be sure, add a step and have the machine shop pre-measure the bores and tell you if you need to go up a grade (if you can) on the piston size. Most likely you don't need to. You have a completely do-able project there and should be back to a good short block in no time. While your parts are in the shop you can turn your attention to the heads.

Ya, that would cause a little rod knock. The 'good' shell also looks like it is down to the copper. Were their oiling issues on this engine? How did the mains look? If you have not built one of these motors before, a good strategy would be to rebuild what you have there to stock. You'll learn a lot and you can keep the cost way down. That way, if there are problems (and there are ALWAYS problems with a rebuild of this complexity; usually, but not always, fixable) you aren't going to blow up a bunch of expensive parts just to find yourself back where you started. Once the first rebuild is a success and you have some confidence, take the other block mentioned in the first post and gather parts for a forged build. Your goals will be clearer at that point. And since everything attached to the SB will be swappable over to the new platform, you really won't be that much behind $$-wise. `Do-it-once-and-do-it-right' doesn't translate well to these engines, in my mind. I'm sure there are exceptions, but the successful, reliable, high-power builds reported here tend to involve experienced builders/owners that have worked their way up to it. Not always on the Subaru platform, but something of similar complexity.

Aftermarket parts don't necessarily trump OEM. The fit and finish on stock parts is of a very high standard. The use of `graded parts' to hit clearance targets, such as A/B grade pistons and 0/1/2 grade bearing shells give a build on the shortblock that is difficult for a machine shop to beat, even a very good one, using aftermarket parts. If your power target is reasonable, a stock SB (as almost everyone will say) is one of the best options. Push the power limits, then everything changes. Somewhere in the middle?; forged pistons are popular. This explains the Crawford spec. Your parts don't look that bad. A new crank and pistons,* good clean up and hone, plus a couple of sets of bearing shells should get you pretty much back to stock on the SB. The cam bores can be cleaned up by cutting the caps and honing. This is all pretty standard stuff for a machine shop that has seen a few Subaru engines. * I agree with StkmltS that Crawford is your best option for stock pistons. You can't beat $25x4 if they are still available.

you can't get the concentrated heat you need with a torch. Of any kind. By the time the core of the bolt head was glowing, your cam gears would be either a) melted (for the plastic ones) b) on fire (for the oil filled intake VVT ones) To answer your question, I've so far always got them off with a breaker bar (touch wood). But having done plenty of welding, it works roughly like this. With any kind of electric welding, the intense local heat expands the metal; since it has to go somewhere, it distorts and is driven into whatever open space it can find, typically thickening compared to the surrounding metal. Once it cools, it still remains thicker, so it has to shrink in the constrained directions to account for conservation of volume. That is what will loosen the head on the bolt. It is also what causes warping and puckers in almost everything you arc weld if you don't take care with welding patterns and corrections as you go.

Unless you have a clever way to hold the cams rigidly, there is probably too much slack in the system to take much advantage of the impact. Those bolts seem to respond best to a slow and steady high torque, with a good tool bit and a long breaker bar. When they go, they will let loose with a bang but the torque level needed to get there can be really high. By welding a nut on, you are partially breaking the head free because of the heat and post-weld shrinkage, which is, I suspect, why you see them come off pretty easily in the video. Zip. . .

I'm with bonbon on this one. Check your valve clearances. This isn't a fun job, and if you do find a problem, it's even worse to do anything about it, but for both these reasons it seems a too many of these cars don't get the attention they should in the valve dept. Marginally tight exhaust valves may not show on cold compression. The valves need to heat up. Hot compression test is not really an option, or at any rate, not for the faint of heart. Same problem with a leak down test on a cold engine. After following this issue for some time, I'm starting to think a significant number of these engines are torn down for suspected ring problems, when in fact it is the top end and valves that are to blame. Mine, for example.

I'm super interested in seeing how the oil consumption settles down long term on this build. Keeping my fingers crossed for you.

Is it engine lube oil, gear oil, or power steering fluid? I don't recall this was settled a few pages ago . . .

The noisy plot on that RPM curve kind of stands out, doesn't it. Out of curiosity, I fired up one of my logs and snipped out a chunk of the rpm curve. I chose a time interval where everything was stable, no misfires etc. Just a completely boring chunk of log. When I plotted the RPM vs time I got the following graph: http://legacygt.com/forums/attachment.php?attachmentid=239262&d=1476548761 Keep in mind that the time units are milliseconds. What I find hard to believe is the oscillations on the order of 30 - 50 RPM multiple times per second. My car has had rough running issues and misfires, but it is stable right now. My question is, how is the crank position, timing, misfire detection etc supposed to work with this kind of noisy signal? The engine has a brand new crank gear, but used (180 K) position sensor. I have not done any tests on the sensor. With all the discussions on this forum about rough running, timing issues, misfires and whatnot, I cannot seem to find anyone who has replaced their CPS in an attempt to solve their problem. Given that so many calculations at the ECU depend on this signal, I'm kind of surprised.

That's an easy differential (no pun intended). Gear oil smells awful, from all the sulphides. Nothing like engine oil. Take a sniff. You didn't have your half-shafts out, so leaking seals is a long shot.

Tell us more! Do you know any conditions for sure that put the MDS to sleep in the 2005 logic? It would be great if you could help to move us from pure speculation to a reasonably accurate reverse engineering of the system!

I know, I remember you saying that you could feel the misfires. But if the crank angle determination is marginal, it could be messing up the MDS as well as causing general timing issues with the trigger signal to one or more cylinders. A scope (as someone suggested before) would help identify the latter, but we don't have a scope handy. In the old days, a simple timing light would show this kind of thing very clearly. A sloppy or loose distributor or worn timing gear line would be the culprit and unsteady idle, general $hitty running the symptom. A bad crank sensor could be the modern equivalent. Ignition trigger is going to be some combination of crank and cam sensors, RPM etc; cam sensors mainly to determine what stroke the cylinder is on. The lead angle parameter must be crank position because the cam sensor does not seem to be designed (from the look of it) to be nearly as accurate for this. If the crankshaft trigger signal is moving around, that would explain a number of symptoms, but not all. As far as MDS cutting in and out, I think the most curious things about your logs are the long long periods of positive but stationary count. I wasn't actually joking when I commented this could be a clue. To me, it is pretty bombproof evidence that the system is blasting through what should have been a count reset under some conditions (wheels moving as a best guess) and therefore must be inactive at those times. Contrast this with a long string of zeros, which contains no information about active/inactive status for the MDS. What is causing the MDS system to cut out, we don't yet know. But it may be quite unrelated to the actual misfires, if you see what I mean.

I didn't want to confuse the above post with wild conjecture about what this means for our specific problem here. However, as an attempt to widen the focus, consider the following scenario. Suppose that the misfire free periods are actually just the MDS being suspended by some other glitch. This would include suspending the reset count, leading to long periods with the system holding whatever count it currently shows. Now suppose that you have a bad or marginal crank position sensor; the observation that the problem is mostly showing up in #2 and #3, two cylinders that are in exactly the same position on the crank (but 360 degrees out of timing phase) may not be a coincidence. Suppose the MDS is reporting misfires, like, all the time. Finally, suppose you have an overly active rough-road suppression signal disabling the MDS whenever the car is moving. That would lead to a very different interpretation of your recent logs. Periods of no activity or flat counts would indicate a problem, not a lack of problem. Up to this point we have been thinking exactly the opposite. Question: Do you have the same crank sensor as pre-rebuild? Have you gone through the FSM diagnostics on it?

I think we need to start a project to figure out how the subaru misfire detection system (MDS) works. Unfortunately, we don't have much to go on. I've not found anything definitive in the FSM. From the web, you get mostly shallow articles; the best I could find was this one. Unfortunately, it is a discussion of generic systems with lots of 'some manufacturers do this . . . ' and we don't know specifically what is going on with our cars yet. Let me start trying to collate this information. I'll start with what we 'know' from the article. When/why does the MDS decide to reset the count to zero? From the article: Any misfires that occur are recorded every 200 revolutions of the crankshaft. The tally is stored in 16 memory blocks, so every 3,200 rpm the misfire count starts over again.' Something like this is mentioned in other articles, so let's assume for the moment it is approximately correct. What I previously thought was a timed reset, is in fact a rotation count reset. Since we were mostly monitoring around idle, time was a reasonable surrogate for revolutions. We can backwards engineer the count used by Subaru by integrating the RPM log between two hard resets in a good log. I tried this on some of StklmS's recent logs but got unreliable results. However, we may have some confounding factors in those logs. Is the MDS active at all times? Apparently not. For example The OBD II system is usually programmed to ignore misfires when the engine is cranking, and when a cold engine is first started. It will also ignore misfires during decel when the fuel is momentarily cut off. and One of the drawbacks of using a crank sensor to detect misfires is that it can sometimes be fooled by normal powertrain vibrations. Driving on a rough road, for example, may produce variations in crank speed that seem like misfires but are not. Some OBD II systems monitor inputs from the ABS wheel speed sensors to tell when a vehicle is driving on a rough road, and disable misfire detection until the road smoothes out. So reports that the car only misfires after it warms up could be misleading. Also, if your ABS sensors are messed up, that could interfere with the MDS! Our cars have another system monitoring pitch and yaw. Inputs from that system may be part of the subaru MDS algorithm. Who knows? Could a lightweight flywheel be a factor in causing `phantom' misfires reported by the MDS? I posted a link to a discussion about this in earlier posts. This seems probable, as in, while it is not the case that every LWFW will cause problems in every car, it will increase the chance of the MDS observing unsteady crank rotation, especially at lower RPM. << space for further discussion/comment >>

Maybe it's another clue

If you look at the CSV sheets, the misfire count resets to zero every 8 seconds, and it does so simultaneously across the cylinders. There must be a counter in the ROM. I don't think it has anything to do with how long you are in gear or not, or how high the count goes (although there is evidence from Bonbon that it cannot go past 99). Every 8 seconds all four cylinders are set to 0 and the sum begins again.

^^^^ beat me to it! I was trying to find the location -- still not sure. Somewhere on the transmission but the FSM doesn't seem to be clear about this. Could be interesting.

Compelling log. I'm thoroughly stumped on this one. With trans in neutral you have very little added inertia in the system and yet, nothing happens until the wheel speed hits zero.

Misfires disappear with the car moving. While moving, you also add in the extra inertial moment of the drivetrain. Could that be a key? I vaguely recall you tried an experiment where you coasted with the clutch engaged. Did the misfires come back while coasting? Just to be sure, when you say LWFW you mean light weight, aftermarket, whereas, single mass FW is what we often install, in place of the stock dual mass flywheel by using the 2008+ WRX setup. Light weight is what you have, correct?

Yes, I understand, but before, I assumed from your description you only had misfires in #2. Is that still the case? I would not have noticed the misfires in other cylinders in your recent posted log just by scanning the spreadsheet. But if you do a column sum they show up. If indeed you have misfires in three of four (or four of four) cylinders, that is something to take into account. Also, I thought this was a completely stock setup, but I see now you had a lightweight flywheel reported in post 1. How come? And how light? Rough idle and misfires are sometimes reported when LWFWs are installed, reducing the inertial mass compared to the stock flywheel. For example, see this NASIOC sticky I have no experience with lightweight flywheels. But I recall momentum scales linearly with inertial moment, so a LWFW could be messing with the roughness detection algorithm, especially at low RPM. Did you re-use the LWFW in the rebuild? If so, it should be put into the list of things to look at. As I said, include all things that didn't change during the rebuild.

Can you check the log you made with this ROM, or record a new one and confirm that you are misfiring in all cylinders except #1?

From those logs, cylinder 1 is actually the outlier, with no misfires recorded in the log. Misfire counts over the combined dataset are (cylinders #1 - #4 respectively) 0, 4235, 1105, 114 So what is right about #1 that is not right with the others?? Try moving things between #3 and #1, for example. Try to move the zero. It is tempting to swap with #2 but there may be other problems with that cylinder. There could be something global going on, like an MAF problem or airflow leak, but why then is #1 perfect and apparently not affected by any of this???

It sometimes takes a while for the accumulation from a simple leak to drain through the undercarriage. Maybe all you are seeing is the residuals from the coolant leak above the turbo. One trick I learned from a diesel mechanic: after 'fixing' a leaking joint or hose connection, blow it off well with compressed air. Any new drops or wetness means it is still leaking, not just residual drainage from behind the hose/fitting. Also, spray around under the leak to distribute the mess -- it will either evaporate off without dripping, or coat things with a fine mist of oil, which also won't drip.

Double clamp it and move on