well....crap. please help

[JazzAvi8r]

I actually just bought something similar a week or so ago. haven't used it yet, but perhaps I will. the cylinders looked absolutely fantastic when I had the heads off. still had great cross hatches on them, the tops of the pistons looked pretty good too with little to no carbon build up. I would suspect a valve problem except the leakdown test was good. I still think it's timing related.

 

at this point, i'm still very open to any and all suggestions -- even the way left field crazy stuff. tell me what kind of diagnostic test you'd like me to run, and I'll post back with the results.

[ehsnils]

If you are sure the cylinders are OK (you could still have cracked or stuck/dehardened piston rings though) then what's left is the valves, so check the valve gaps. It may not reveal the full story, so a leakdown test is next step - and then it can either be bent valves or burnt valves.

 

One crude way to check the piston rings is to start the engine and take off the oil filler cap and check how much it "breathes". If you have a car with a good engine to compare with it's good since then you can get a reference on reasonable "breathing".

 

It may of course still be a timing issue and one of the cams for the 2&4 bank may be "off" for some really stupid reason, like broken sprocket key or something.

[JazzAvi8r]

ehsnils,

 

leakdown test passed with flying colors. I doubt it's the valves. <1% on cyl1&3; <5% on cyl2&4. yet the compression is still stupid low. that leads me to believe the valves and the rings are fine. would you agree?

[xt2005bonbon]

Just to be sure, you need to do the leakdown test warm. As I previously said, I did two cold leakdown tests on two different cars. Both yielded good results and yet both had a completely tight exhaust valve.

[ehsnils]

Then I would consider to narrow this down to that it's either bad valve gapping, a weak valve spring or that one of the cams is badly off in timing.

 

I'd take off that head and make a very thorough analysis of it. Even inspect it for cracks and warping since a leakdown test only put a certain amount of pressure on the head and if it's cracked or warped that may not be revealed unless the pressure increases above a certain level.

[JazzAvi8r]

yeah, I believe that's what its going to come down to. I tried hooking up BtSsm last night with a Vag-Com and for whatever reason, my phone wont allow it to connect to the ECU. I've already enabled developer mode, factory reset the phone, and tried various settings to no avail. I guess I'll just have to buy the Bluetooth connector and go that route. Unless someone else has a suggestion on that front.

 

This weekend I'm doing a clutch and ISB on a civic so I wont have much time to work on this car. If it comes down to it and I have to pull the head again, I will swap out the head gasket with a 6star unit instead of the OEM TLS gasket. maybe that will help? Pretty sure I shouldn't use the gasket that's currently on it even though it has less than 10 minutes of run time on it.

[JazzAvi8r]

I'll do a warm leakdown test before I pull the engine just to be sure. I might actually be able to do it on Thursday night.

[xt2005bonbon]

yeah, I believe that's what its going to come down to. I tried hooking up BtSsm last night with a Vag-Com and for whatever reason, my phone wont allow it to connect to the ECU. I've already enabled developer mode, factory reset the phone, and tried various settings to no avail. I guess I'll just have to buy the Bluetooth connector and go that route. Unless someone else has a suggestion on that front.

 

PM heiche or post on the btssm thread. He will help you troubleshoot this issue. Should be an easy fix I think.

[ehsnils]

I'll do a warm leakdown test before I pull the engine just to be sure. I might actually be able to do it on Thursday night.

If that doesn't reveal anything then hand crank to different positions to see if you can detect when the valves opens. Maybe that can reveal something too.

[xt2005bonbon]

True. You could also use a high definition borescope type camera to actually see them. If you do, make sure you buy a good one.

[gkinslow]

True. You could also use a high definition borescope type camera to actually see them. If you do, make sure you buy a good one.

 

 

I recently bought a cheap one for looking around under the intake manifold and couldn't make out a damn thing.

[xt2005bonbon]

Exactly. I also bought a cheap one to see if my ringlands were shot. Picture was pretty crappy. Color reproduction was poor. AND it was a pain to try to rotate it 180 degrees to see the valves. Soooo yeah, get a good one.

[JazzAvi8r]

I do have a boroscope -- just haven't tested it out yet. maybe this weekend after the clutch job.

[1-3-2-4]

Exactly. I also bought a cheap one to see if my ringlands were shot. Picture was pretty crappy. Color reproduction was poor. AND it was a pain to try to rotate it 180 degrees to see the valves. Soooo yeah, get a good one.

LOL did we get the same scope? Despach or something like that.. Here is one of the shots I grabbed while I was inspecting my FMIC for turbo bits.. I wrote a nasty review and I got refunded the full amount if I would remove the bad feedback.. I wont be bribed so I left the neg review up.

[JazzAvi8r]

^ savage!! i like your style

[JazzAvi8r]

Sorry for the delay. Here's the first two logs. What do you think? I noticed the,misfire events after the logs ended as i was pulling bavk in to tue garage

BtSsm_20171217_183024.csv

BtSsm_20171217_182941.csv

[xt2005bonbon]

oh yeah. I can see 2 and 4 clearly misfiring. IIRC, the misfire CEL gets triggered if it hits 30+ a couple of times in a row or something. At least, that's what I experienced several times in the past. FYI, these misfire counters max out at 99 and reset. But yeah, something is definitely going on the driver side bank. Looks like your passenger side is fine. A count of 1 can be completely ignored IMO.

[JazzAvi8r]

Right, i know the misfire events are likely a result of me having low compression on those two cylinders. The question is why is the compression low?

[xt2005bonbon]

Ah the million dollar question. I don't know man. I mean, you've checked almost everything. The only thing I see that is left to do now is tearing down that side of the engine once again, which definitely sucks. Have you checked the valve clearance on that side to make sure you can rule that out?

[ehsnils]

Yes, I agree, it really requires a thorough analysis of that side - including that the sprockets are correctly keyed in position for the camshafts.

[AndySTi]

Yes, I agree, it really requires a thorough analysis of that side - including that the sprockets are correctly keyed in position for the camshafts.

This

[BarManBean]

IIRC he has checked that the sprockets are installed correctly already.

[aj_mariner]

Started with a 2 and 4 misfire at 195k. Got it resolved for 10k and am now dealing with a cyl 4 misfire only in cold temps. If those two cylinders weren’t the most touchy, I would suspect the intake and exhaust AVCS oil control valves.

 

Edit: can you see the AVCS oil control valve duty cycles? Does it misfire all the time or only during certain loads?

[JazzAvi8r]

i will do another log with the AVCS d/c. Going to count the teeth today to once and for all rule out timing. looking at the screenshot, IAM seems pretty high. I interpret that as the ECU seriously advancing timing to keep the car running -- which means timing is still the culprit. if I'm wrong on that, please chime in and let me know. I don't claim to be an expert by any stretch.

[rhino6303]

i will do another log with the AVCS d/c. Going to count the teeth today to once and for all rule out timing. looking at the screenshot, IAM seems pretty high. I interpret that as the ECU seriously advancing timing to keep the car running -- which means timing is still the culprit. if I'm wrong on that, please chime in and let me know. I don't claim to be an expert by any stretch.

The IAM is part of Subaru's knock control strategy. Your ecu will always try to have the highest possible timing. When conditions are met and your ecu detects a knock event the IAM may lower to reduce the timing in order to control the knock. Once the knock subsides and conditions are met the ecu will higher IAM again and therefore increase timing.

 

It is part of a three piece control strategy with both fine learning knock and feedback knock. Each piece of the puzzle has different conditions that must be met in order to be active such as load and rpm.

 

In general the two in the strategy people focus on most are IAM and fine learning knock as feedback knock tends to hear false knock events such as throttle lift, etc.