RomRaider

Just a little followup - it turns out the wastegate/bcs don't seem to be at fault here. Still looking for the issue though.

Not sure how 2018 went by so fast but I haven't been able to look into this any further until a few weeks ago.
I did manage to do a boost leak test a few months back where I found all four intake manifold gaskets (the orange ones) to be leaking quite badly. Easy fix right? 25 bucks and about six hours later with surprisingly little swearing, another boost leak test showed no leaks at 15 psi.

That fixes everything, right?
Wrong!

I've been hesitant to post here since my issue seems to be mechanical rather than ECU-/sensor related, but maybe somebody has an idea as I need all the help I can get.
This is what I posted on nasioc:



Here's a recent log:
https://docs.google.com/spreadsheets/d/1-wDYpbcwyu-0pdngH_YObdtiefWQFytBhmyjqj8iGsU/edit?usp=sharing

One or both tgvs stuck closed?

That has actually crossed my mind after I couldn't find anything last time.

So I drove around a little bit and logged the TGV position. It looks like they do open and close just fine. But then again, wouldn't the car throw some codes if they weren't? Would it make sense to confirm that the blades are physically moving? From what I've read I might be able to take off the block off plate on the front of the driver's side TGV where the sensor used to be on earlier models and visually confirm that the rod is in fact rotating.

Also, it does seem odd to me that the max. voltage is 3.6V in what I assume is the open position. Shouldn't it be closer to 5V?

Tgvs are long gone on my car, so I can't confirm, but to my knowledge tgvs should be closed for only a short time after a startup. Afterwards IMO they should stay open at all times. The log in this regard seems suspicious.

08 onwards (and some 07's!) use the TGV's when cruising to try and get more swirl/better burn - usually comes a second avcs and timing map also. Though I'd be of the same thoughts once the car is ready open them up and keep them open.

Good to know! In that case, the log appears fine.
Though I'm not sure you can tell by logging that they indeed open normally in a mechanical sense. But as op had stated above, if there is a problem it should throw a CEL.

Yes I've read about the advanced TGV function they started implementing in the '08 models. I did log it again with the engine fully warmed up and a little more load and the TGVs are open a lot more. Also, 3.6V seems to be what other people see as well so everything looks fine.


Next I looked into my secondary air system. Stuck open valves would result in a pre-turbo exhaust leak and therefore low boost.
So I logged Secondary Air Piping Pressure (didn't even know it had a pressure sensor in there?)



Again, it seems to be functioning normally. The pump is active during warmup resulting in pressure slightly above atmospheric (16-17 psi). The pump shuts off after about a minute (which was odd, I can usually hear it shutting off after about 15 seconds), and the pressure drops down to 13.9 psi, same as atmospheric pressure.
As with the TGV valves, I'm wondering whether there is any point in physically checking if the valves do indeed close as I'm not sure whether I would actually be able to see raised pressure in the secondary air piping if the valves weren't closing properly. I'm not sure the air pump will actually block any air (exhaust) from escaping once it's shut off? However, stuck valves *should* throw a code as well making it quite unlikely that this is the cause of my issue.
Just to make sure I'll unbolt the air pump and see if there are any exhaust fumes coming out of the hose when the engine is running. Just haven't gotten around to it yet.


I also went ahead and logged my VVT angles. Though they're off by a few degrees every once in a while, overall I didn't notice anything out of the ordinary.
Note that the system is inactive until the engine has warmed up to about 140°F. That's why VVT is at zero at the beginning of the graph.




I have now completely run out of ideas. Maybe pushing it in the river might be a viable next step.

Are you absolutely sure wastegate and BCS are ok?
Because in that log you posted boost is matching spring pressure numbers pretty much exactly.

I am 100% certain it's not a wastegate issue. I basically wired the wastegate shut using a heavy spring to put a lot of preload on the arm and also unplugged the vac line from the actuator (plugged the vac line itself with a bolt). It should've been making boost like crazy, but it didn't. Same max values as before.
I also took the downpipe off to inspect the flapper. It opens and closes as it should, doesn't catch on anything, mating surfaces look to be in good shape, no corrosion, no cracks.


Since I did an oil change 1000 miles ago it's burned not even half a quart of oil. There's definitely some oil in the intake post-turbo, but nothing I'd consider alarming really. Maybe 1 or 2 drops come out of the intercooler whenever I take it off. The intercooler itself isn't clogged, at least I wasn't able to feel any resistance blowing compressed air through it.

Oh and there's two more issues that have started appearing recently, which I doubt are related but I thought I'd share anyway:

One, the car's been throwing a sporadic P0038 CEL (HO2S12 Heater Control Circuit High). Doesn't seem to be that big of an issue. Some people recommend disabling it in the rom as a fix.

Also, it'll only run on three cylinders right after startup. It's barely noticeable (maybe half a second) when it's warm out and lasts about two seconds max when it's chilly in the morning. It'll idle fine after I touch the throttle. Of course every time I take my laptop with me to try and log any misfires, it starts almost fine and romraider doesn't detect any roughness so I haven't been able to figure out which cylinder is causing it. Once I do I'll be swapping some coil packs/plugs around to try and narrow it down.

I reckon the 08 wrx factory 2 port solenoid is horrible!
I tried tuning with the 2 port, just to get some sort of decent boost, as factory, my car peaked at 10Psi, and weaned off to 8 on wot.
I’ve swapped in a Mac 3 port, used the restrictor in the turbine hose, altered my wgdc tables conservatively, and tweaked the boost fuel cut and dynamics.
Even with it now holding 11-12psi, it’s smoother and more linear power.

Personally, a 3 port should be one of the first things to get.