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Stock EJ20G low boost?

Posted: Tue Oct 06, 2015 7:56 am
by Mpgingerson
Now that winter is ariving here in Norway, the air is getting to freezing tempatures, but my car is not going as well as before. When the turbo spools I don't get the kick of it kicking it anymore, I just hear the spool and a small increase in power. I had a boost gauge connected and before I reached the preassure a stock Subaru makes, but it dropped alot, more than half that power. I checked the vacum hoses and noticed the T for the boost gauge was cracked, so I removed everything including the boost gauge and hooked up a new vacum hose, and the power is a little more, but not as much as before.

The car is bone stock, but the oil is very thick 10w60 Castrol Edge, so I'm going to change it today to a thinner Mobil1 and update, and so reset the ECU (disconnecting battery terminal), hoping it will work and that my engine and or turbo isn't dying :((

Re: Stock EJ20G low boost?

Posted: Tue Oct 06, 2015 7:20 pm
by robertpaige
10w60??? Jesus. Put a 10w30 at least for that temp outside.

Honestly sounds like you have a post turbo leak. I would smoke test it. But if you can't do that just look around and check all your hose clamps and fittings. The fact you fixed a broken vac T and it got better points to a vac leak somewhere else.

Re: Stock EJ20G low boost?

Posted: Wed Oct 07, 2015 9:24 am
by Mpgingerson
robertpaige wrote:10w60??? Jesus. Put a 10w30 at least for that temp outside.

Honestly sounds like you have a post turbo leak. I would smoke test it. But if you can't do that just look around and check all your hose clamps and fittings. The fact you fixed a broken vac T and it got better points to a vac leak somewhere else.
That was the oil that was in the car when I bought it recently, don't judge me :((((( but yeah, I'll look around, but I've changed all the hoses all around, but something could have loosened up

Re: Stock EJ20G low boost?

Posted: Sat Oct 10, 2015 5:56 pm
by Legacy777
If you've had a vacuum/boost leak for a while the ECU could have some learned boost trims in it. I'd suggest resetting the ECU once you've verified you no longer have any leaks.

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 10:04 pm
by Mpgingerson
Okay it's been some time, but this is starting to really annoy me... The car is still doing the same stuff, only charging what seems to be half of the boost it should. For mods in the intake I have the Apexi intake w/coffee can mod included (yes the restrictor pill is in, and I've tried without aswell, still low on boost). I've now tried to clean every single hose and changed some of them, cleaned the boost solanoid in test mod and it clicked and whirled like crazy, so it works as it should.

During the winter though the car worked fine, but it's when the weather got near summer it changed back again. Now it's like, I can reset the ECU and do a couple off pulls with full boost, but it's when I stop and cruise for like 5 mimutes it goes back and boosts only half... When it's on full boost I can hear the turbo spool up really loud and the intake noise is loud and lovley (because of the intake), but on half boost it sounds like it won't take as much air and the turbo spools and get's stuck (?)...

I have a manual bleed valve from GFB by hand, but I've not really taken the time to i stall it.. Should I install it and keep it on the stock boost level? (Still have the stock exhaust, stock WTA intercooler, etc, so nothing above the factory boost)

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 10:38 pm
by mike-tracy
How old is the coolant temperature sensor? Do you have any check engine codes? The GFB manual controller *should* work of course. but if your car has a serious problem that the factory electronics are detecting and tapering back boost because of, then adding a manual boost controller could be bad for the engine.

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 10:46 pm
by Mpgingerson
mike-tracy wrote:How old is the coolant temperature sensor? Do you have any check engine codes? The GFB manual controller *should* work of course. but if your car has a serious problem that the factory electronics are detecting and tapering back boost because of, then adding a manual boost controller could be bad for the engine.
I'm guessing as old as the car haha.. Yes, that's my thought exactly.. I want to detect the problem instead of hiding it, but I think it's weird as how the car works splendid sometimes, but most off the time it's just lacking that extra spool haha.

Oh and no CEL's or error codes, I checked it yesterday while I had the BCS tested.

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 10:53 pm
by mike-tracy
Try a brand new factory coolant temperature sensor. It is the one with a plug on it, not the one with a single blade, both are located under the intake manifold, on the coolant crossover pipe. It seems almost like magic how many problems a new one solves. It may not be your only issue, but the ecu makes a lot of decisions based on the CTS.

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 10:55 pm
by Mpgingerson


Here is the car when it's boosting fully.

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 11:00 pm
by mike-tracy
Sounds real good! I'm sad we didn't get any snow in the lowlands this winter. I was too busy with work to head to the mountains either.

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 11:06 pm
by Mpgingerson
mike-tracy wrote:Try a brand new factory coolant temperature sensor. It is the one with a plug on it, not the one with a single blade, both are located under the intake manifold, on the coolant crossover pipe. It seems almost like magic how many problems a new one solves. It may not be your only issue, but the ecu makes a lot of decisions based on the CTS.
Yes, I've sent a mail to Subaru to order it :)

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 11:12 pm
by Mpgingerson
mike-tracy wrote:Sounds real good! I'm sad we didn't get any snow in the lowlands this winter. I was too busy with work to head to the mountains either.
Well thanks! :D Yeah snow is both hated and loved from my point of view haha.. Perks of living in Norway ;) But these cars sit so good on the road it's near impossible to drift it without going full Colin Mcrae!

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 11:15 pm
by Mpgingerson
Some people I know says that the car is stuck in limp mode? What is this?

Re: Stock EJ20G low boost?

Posted: Sun Jul 10, 2016 11:21 pm
by mike-tracy
Check the ecu for codes. Directions here. http://www.surrealmirage.com/subaru/engine.html
Certain codes cause the ecu to run the car with reduced power, timing and boost.

Re: Stock EJ20G low boost?

Posted: Mon Jul 11, 2016 5:33 am
by Legacy777
The other thing I'd suggest is putting the boost control back to stock and any other "electronic" type things. This should allow the stock ECU to react normally to how it would if it detects something is not working correctly and may be another troubleshooting technique if the coolant temp sensor doesn't change anything.

Re: Stock EJ20G low boost?

Posted: Mon Jul 11, 2016 1:47 pm
by Mpgingerson
What's the part code for the temp sensor?

Re: Stock EJ20G low boost?

Posted: Mon Jul 11, 2016 9:59 pm
by Mpgingerson
Just found something out. If I drive agressive and cruise for some time at around 2500-3000 rpm the car will boost fully.

Re: Stock EJ20G low boost?

Posted: Thu Jul 14, 2016 1:06 am
by Legacy777
Mpgingerson wrote:What's the part code for the temp sensor?
http://bbs.legacycentral.org/viewtopic.php?p=4970#p4970

Re: Stock EJ20G low boost?

Posted: Thu Jul 14, 2016 1:08 am
by Legacy777
Mpgingerson wrote:Just found something out. If I drive agressive and cruise for some time at around 2500-3000 rpm the car will boost fully.
Have you checked for any codes active or stored? How long does it boost fully?

Re: Stock EJ20G low boost?

Posted: Sat Jul 30, 2016 4:43 am
by klapasch
Try checking your diverter dump valve, take it out and blow air inside. Mine is KO, you can whistle air through it.

Re: Stock EJ20G low boost?

Posted: Thu Aug 04, 2016 11:25 pm
by Mpgingerson
Legacy777 wrote:
Mpgingerson wrote:Just found something out. If I drive agressive and cruise for some time at around 2500-3000 rpm the car will boost fully.
Have you checked for any codes active or stored? How long does it boost fully?

Checked both active and stored.. But when the green wires are connected and ignition is only set to on, the CEL is flashing, but not in a "code" way... It's flashing with the same intervall all the time.. Like (flash-flash-flash-flash) no pause or no delay, repeating itself.. And what do you mean how long does it boost fully? Like how long ln the revrange or how long in time? On the revrange it holds strong as it should, but in time.. I can reset the ECU, go out and do some pulls straight away, but it's when I stop pulling and drive casually the car just flops and decreases the boost untill I reset the ECU again...

Re: Stock EJ20G low boost?

Posted: Thu Aug 04, 2016 11:51 pm
by Mpgingerson
klapasch wrote:Try checking your diverter dump valve, take it out and blow air inside. Mine is KO, you can whistle air through it.

Did it, the diverter valve was ok :O

Re: Stock EJ20G low boost?

Posted: Fri Aug 05, 2016 12:10 am
by Legacy777
Hmmm

I'm not sure what to tell you without some more diagnostic information. Do you have a wideband O2 sensor to check AFR's?

Forgive me if you've posted this elsewhere, but do you have a boost gauge and if so what boost pressures are you seeing when things are running normally and what are you seeing when things are not working?

Have you tried running a manual boost controller to see if the problem remains or if it goes away? That may be a cheap testing option to try and narrow things down. Have used compressed air to blow out all the vacuum lines to make sure they're not plugged?

Re: Stock EJ20G low boost?

Posted: Fri Aug 05, 2016 12:48 am
by Mpgingerson
Legacy777 wrote:Hmmm

I'm not sure what to tell you without some more diagnostic information. Do you have a wideband O2 sensor to check AFR's?

Forgive me if you've posted this elsewhere, but do you have a boost gauge and if so what boost pressures are you seeing when things are running normally and what are you seeing when things are not working?

Have you tried running a manual boost controller to see if the problem remains or if it goes away? That may be a cheap testing option to try and narrow things down. Have used compressed air to blow out all the vacuum lines to make sure they're not plugged?
I do not have a wideband sadly :( I'm waiting untill I get my exhaust done.. And I think I've posted something similar before, but on another forum :O I did have a boost gauge before, but took it out due to not really needing it at the time.

And no, I have not tried a manual boost controller because the car is close to stock and I'm scared of ruining it, but I have one at hand.. Still need to get a new boost gauge and wideband for it though..

And for the vacum hoses I've changed all of them, and yes I changed the one with the restrictor pill in it. I reinstalled the pill exactly the same way and air got through it like before..

I've also cleaned the entire intake part of the car, as well as the boost solanoid and other stuff connected to the intake..

this is what it boost normally.

Re: Stock EJ20G low boost?

Posted: Fri Aug 05, 2016 5:35 pm
by Legacy777
You don't need to up the boost on the MBC, you just need to see if it will maintain the correct boost pressure as stock. If it does then you know there may be an issue with the boost control electronics or something is up with the input sensors/data that tells the ECU what to set the boost at.