over boosting need help

This is my first turbo car its a 2006 lgt bitchomatic bone stock. I've had it for a couple of months now and a couple of weeks ago i got on it hard to merge onto the highway it boosted hard and the it seem it lost boost (fell on it's face hard ). This happend for like a second then got boost and the cel came on. Took it to 2 local auto store to get the cel check and was told it was the waste solenoid. After this has happen it felt like it was over boosting so I bought a boost gauge, It's boosting all the way to 20psi. Now theres a rattling noise coming from the turbo not sure if it's the turbo but car still has power and it does not smoke at all. My friend told me to get a mbc and set to stock boost for now. Is this a good idea as I have read it's not good run mbc on subaru and i've read some people run mbc on them. I'm not going to be doing any upgrades right now but is it ok to have it now for down the road when I do upgrade. Can someone please give me some advise on what to do since I am new to turbos. Heres a video of what the turbo sounds like,doesn't look good to me. [ame=http://www.youtube.com/watch?v=0ZAaahYaH08]PIC 0508 - YouTube[/ame]

one of the vacuum lines probably came off..

I've check all the line everything seems to be in place. thanks

Theres a T between the turbo and the wastegate. one of those lines may have popped off. They are short and hard to see. The line goes forward of the leg of the T under the intake manifold.

 

I'd look again.

blue T under the intercooler? that one got me when i first got the car, now its zip tied snug!

It's the waste gate itself. It is stuck in a partially opened position due to the bushing getting shifted. You are probably not making much boost at 3500 rpm, around 6-8 psi. It's making too much at redline, right?

 

The noise is probably the rattling of the waste gate.

1. All the holes going to both t's are connected I even put zip ties as for boost at 3500 rpm it's above 5psi at 4000 rpm it's hitting 15psi at 4500 rpm it's hitting 20psi and when I get to 5000 rpm it hits 22psi cuts out cel comes on and cruise control light start flashing.
   

Theres a T between the turbo and the wastegate. one of those lines may have popped off. They are short and hard to see. The line goes forward of the leg of the T under the intake manifold.

 

I'd look again.

 

 

^ This!!

Theres a T between the turbo and the wastegate. one of those lines may have popped off. They are short and hard to see. The line goes forward of the leg of the T under the intake manifold.

 

I'd look again.

 

x3.

 

these words could simply answer 5 posts a day.

check all of them and there in the t's , I even zip tie them. As for the boost it hit between 5psi to 15psi from 3000 to 4000rpm from there on it will it up to 22psi. But if it was a problem with the waste gate how could that be fix.

5-15 is a pretty big range. Is this with a 3rd gear pull?

 

First picture is what the waste gate looks like when it has shifted. 2nd picture is how much the bushing is sticking out. Compare to the turbo in this link http://legacygt.com/forums/showpost.php?p=1972290&postcount=3

 

Does yours look like that?

So i finally got to pulling the turbo out and yes scotty your were right. The waste gate did shift, so a bought a blown turbo and replace the back half. Thanks for all the help guys.

 

wow shitty turbos ..

tell me about it, but theres was no shalt play at all I mean nothing like if it was brand new.

Thats why i went with a bnr supercars hta 68 and i love it no problems

interesting, I've had the same problem earlier this year. I've hit overboost and had that solenoid CEL a few times, sent ecu map to tuner and had it adjusted. I wonder if my wastegate shifted as well. Would warranty cover the turbo for shifted wastegate ?

I suspect if you remove the roll pin, you should be able to push the wastegate back. I haven't gotten around to doing it on mine. My turbo had over 180K miles on it, most with Mobil 1 No shaft play, just the wastegate issue.

It's the waste gate itself. It is stuck in a partially opened position due to the bushing getting shifted. You are probably not making much boost at 3500 rpm, around 6-8 psi. It's making too much at redline, right?

 

The noise is probably the rattling of the waste gate.

 

Does it rattle at all time?

 

I've been hearing a slight rattling lately around the turbo area when not in boost with slight load on engine. And last week, I did a hard pull getting on the freeway and I hit 14.7 psi (stock tune with K&N panel filter--yeah I know..). Two weeks ago, I also hit 13.9 while doing a third gear pull. The 14.7 psi I am not sure in which gear I hit it, cause I was pulling hard in 3rd-4th and 5th.

Otherwise, when the turbo spools, it sounds good and car pulls well. No jerking, no CEL..

Bump .

bump again.

 

I'd add this questions as well:

 

1. Assuming one is stock everything, what are the various causes of overboosting?

 

2. Assuming the whole engine is in good working order on a stock tune, is it possible at times to go over 13.5 psi? Or should it simply never occur?

2. Assuming the whole engine is in good working order on a stock tune, is it possible at times to go over 13.5 psi? Or should it simply never occur?

 

it is possible. conditions like cold weather, low altitude, high atmospheric pressure (not a stormy day), high gear (5th is mostly likely), and high load (going up a hill) can generate an overboost code or cause the car to go above 13.5psi without actually tripping a CEL.

a very obvious rattle in that area is mostly like a turbo or uppipe heatshield that has broken from its welds. the rattle can be rpm and load dependent too which can make it tricky to diagnose.

it is possible. conditions like cold weather, low altitude, high atmospheric pressure (not a stormy day), high gear (5th is mostly likely), and high load (going up a hill) can generate an overboost code or cause the car to go above 13.5psi without actually tripping a CEL.

 

So far, it has not triggered any CEL and I've never had any 'fuel cut' going on. Maybe it has not happened because the max boost it went so far is 14.7 psi. I've only noticed overboost 3 times now (13.6 / 13.9 / 14.7). Conditions outside were very humid, fairly cold (45F) and at sea level.

 

a very obvious rattle in that area is mostly like a turbo or uppipe heatshield that has broken from its welds. the rattle can be rpm and load dependent too which can make it tricky to diagnose.

 

The rattle is very subtle and you usually hear it when NOT in boost. I am going to check for loose stuff around the turbo area.

first off, are you measuring your boost through a boost gauge or the ecu? for years and many different boost gauge brands, they seem to read 1-2 psi higher than the ecu does(due to comps).

 

boost will vary depending on temps and other compensations. if you don't hit boost cut, your ecu find no issue with the pressure it's reading at the map sensor(absolute). if it's a stock tune, i wouldn't worry about it.

first off, are you measuring your boost through a boost gauge or the ecu? for years and many different boost gauge brands, they seem to read 1-2 psi higher than the ecu does(due to comps).

 

boost will vary depending on temps and other compensations. if you don't hit boost cut, your ecu find no issue with the pressure it's reading at the map sensor(absolute). if it's a stock tune, i wouldn't worry about it.

 

I am reading off the ecu (using the Torque Android app). And yes, stock tune.