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Discussion Starter · #1 ·
So just a few weeks ago, i bought a beautiful 2005 outback xt 5 speed. this is the first turbo subaru that i have owned and so far, its been giving me some issues. when i bought it, it had low compression and failed a leakdown test on cylinder 3. this was discovered after the previous owner put all new subaru coils, injectors and ngk plugs in it. i pulled the engine out and had the valves and the seats ground for all the cylinders. my machinist told me that #3 exhaust valve seats took quite a bit to smooth out, that was the low compression. then i put the engine all back together and back in the car. for the first few days, it had the issue of surging and loosing power at moderate throttle below around 3K rpms. twice it threw a code for camshaft a being too advanced and misfires on 2 and 4. it hasnt thrown those codes in probable a week and a half now, yet it still has the same issue. i put a new set of intake manifold gaskets on the car and it actually made the problem worse. so i took some data logs and i cant seem to find anything super unusual. so if anyone could help me, that would be great.
 

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Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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16,225 Posts
Post those logs please.

Have you done an intake pressure test?

Have you done a fuel pressure test?

Do you know what the condition of PCV system is? (inside sludge)

Drop you downpipe and check the turbo.
 

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Discussion Starter · #3 ·
no sludge in the pcv, the turbo is in very good shape, no fuel pressure test. im not entire sure what you mean by an intake pressure test. my logs are all .csv files and it doesnt seem to let me upload those files, any suggestions?
 

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Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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16,225 Posts
no sludge in the pcv, the turbo is in very good shape, no fuel pressure test. im not entire sure what you mean by an intake pressure test. my logs are all .csv files and it doesnt seem to let me upload those files, any suggestions?
Put the csv.file in a zip folder.

Intake pressure test, so, that means pressurizing the intake after the MAF to test for leaks. Similar to a smoke test.

If the turbo and PCV system are in good shape than its possible fuel pressure, vacuum somewhere that affect fuel pressure...or possible boost / wategate issues.

Post your zip and lets see what you have logged. Have you logged the actual surging event?
 

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Discussion Starter · #5 ·
i thought about smoke testing the intake but there will never be a point in engine rotation where all the intake valves are close. if im wrong about that, please let me know. im thinking it could be the turbo inlet hose or the hose from the top mount to the throttle body that are leaking. and yes, i did catch the surging event.
 

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Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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16,225 Posts
Ok, I would agree that the data in your logs looks very normal. But you didn't log what you need too

Example...

engine speed
accelerator Pedal %
throttle plate open %
battery voltage



I have attached a log, please change your parameter list to this. I would ask that you also add ... and log the next time its convenient and post those back.

requested torque
target boost
boost error


if you can. I get limited sometimes.

You are correct about the smoke test, so you end up pressurizing the block as well with a slow leak. But if there is an intake leak that is obvious...it will show.
 

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Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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Could it be the clutch slipping?

The parameter list I sent would show the RPM rising/dropping and the throttle and accelerator pedal angles...
 

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2005 OBXT Ltd Obsidian Black 5MT
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I see a copule of things that don't look quite right.

Your AVCS don't seem to be doing much. I only see them responding in a copule of spots.

The wastegate seems to be doing what mine is doing where it seems to not respond. That causes mine to chug and miss. One of your logs it's working, the other two, nothing. Mine doesn't seem to want to respond after a cold start. Shuttting it off and restarting after driving a few feet seems to fix it, but I don't know what the root cause is.

It also looks like your alternator output is a little low, but not too bad. I get over 14v out of mine, yours is about 13.5v. Make sure the belt is tensioned properly.
 

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Discussion Starter · #9 ·
belt is all tensioned properly, i noticed the lowish voltage too. i think the alternator is just a bit past it. the clutch is definitely not slipping. the car did at one point throw a code for the avcs on the drivers side being too advanced, never any other codes relative to avcs. here are the logs i just took with only that pid list, soon i will go take more with more pids.
 

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Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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Great

The more you log, the more opportunity to see whats going on.
 

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Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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16,225 Posts
Ok I just looked at the logs. (very....quickly) out to log myself...

Open Up the log I attached...You need to log all of those parameters. I meant add request torque and the boost pids if you could to the long list.

Also if you log the surging even, I identify which and long though. I leave my self voice messages...

"surging was 1/3 of the log through, log time now 12:15 pm"

Then I can look at the specific log and zero in. I am no expert. But I can use software and manipulate data viewing.

I see you renamed several with cruising....use the file name as well.

Thx
 

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2005 OBXT Ltd Obsidian Black 5MT
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I don't see it in your latest logs, but was there earlier: Primary Wastegate duty cycle %.

If this isn't functioning, lots of things go wonky.
 

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Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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what does this mean for me? how can i fix that?
It depends whats causing it.

Vacuum leak, ebc not working, tune is messed up, back pressure messing with it.

Most likely a vacuum leak. I need to take some time and look at the new logs. Thanks for jumping in @Logie_OBXT
 

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Discussion Starter · #18 ·
if you could make a list of all the primary pids for logging, that would be great. im new to all of this tuning and logging. not new to subarus, just turbo ones.
 

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And to add, I've been fighting air leaks since I put in a new engine 4 months ago and I think I'm finally getting them all straightened out.
 
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