Boosting Problems (wg related)

[guitarXgeek]

Hey guys, I'm having a bit of trouble boosting as of this afternoon. I was coming home from school and a buddy of mine was behind me, so I decided to give it a little WOT in 2nd gear . Anyways, I noticed that it didnt feel quite as strong at all as it usually does. I did a 3rd gear pull immediately after to see where my boost was, cause I had just installed a MBC (bleeder-type) the previous evening. To my surprise, the gauge shot up to around 22+ psi! It was only there for a maybe a quarter of a second, so no damage was done (at least I think). I pulled over to the side of the road and turned the MBC ALL the way in, so that the boost would/should drop to around 9 psi (I think that's what the actuator is set to). Then I went out and tested it again, and results showed it was still boosting insanely high, ~22 psi.

This kind of worries me, because I had been boosting earlier in the day today with no problems and boost stayed at ~15 psi. I'm thinking maybe the wastegate is just stuck closed. I don't know why this would be, but it's the only thing I can think of right now. I tried pulling on the actuator arm to see if it would move, and it didn't (not sure if it's supposed to or not). Is there any way to test if the wastegate is staying closed shut?

I've already tried running a line straight from the pressure source (intake mani) to the wastegate actuator. This helped a LITTLE bit, but it still was boosting to around 19-20 psi as opposed to the 23+ when the controller was there. Help?

Any help would be appreciated!

Matt

 

[xaosgst]

It is possible for your wastegate to get stuck. I had that happen to me on an internal.

You did the right thing by eliminating the boost controller from the picture. Make sure ALL your vacuum lines are intacked and you have no boost leeks anywhere.

If you have an electric air pump then try your best to rig a connection to feed into the wastegate. I was able to just hold it tight enough to test. turn the pump on and note how much PSI it takes to begin to move the wastegate arm. Typically you won't be able to move it with your hand as it requires a crap load of effort.

If its a 10psi WG then it should begin to move around 7 or 8psi. These thigns just don't slam open at the predefined pressure. If its a 15psi unit then you should start to see it open around 12-13psi.

If it doesn't open till WAY above what its supposed to then it may have an internal problem. If it works fine then you can go lookin somewhere else

 

[Generation1JeY]

mine did the EXACT same thing, one day it just started to just free boost, so i checked everything over twice, and it turned out it was just a broken wastegate, so i ordered a new actuator from machv, and that fixed the problem.

The way to check is just get a pressure pump and plug it into the actuator and pump to see if it opens at 10psi or whatever it normally does, if it doesnt open or it just lets the air through then the wastegate is broken and u need a new one, for me the diaphram was punctured i guess so that it wouldn't develop enough pressure to push the spring, it would just bleed through.

 

[sonicnofadz]

Do EXACTLY as Generation1JeY said. Go to autozone or wherever and pump one of those hand vaccuum pumps (there like $20-30 bucks, not bad) and plug it into the wastegate actuator and see if the arm moves when 10psi is reached.

 

[Generation1JeY]

if it doesnt then the actuator is toast. period.

u can get a new one from machv for 90 bucks or if ur lucky u can score one from a junkyard or whatever, infact i'm not even sure u have to get one that fits perfectly, because if ur running a mbc it doesnt need to be the exact same spring setup.

U just need to make sure that it will fit and move the wastegate flapper correctly when it reaches its boost limit.

 

[guitarXgeek]

Alright, I've got another update for you guys, and I think I have found the problem. After taking off the entire exhaust mani/turbo/o2 housing out as one, I noticed that the new gasket we put on last weekend that connects the turbine outlet and o2 housing was a bit... off. I don't know if it's because I'm using an evo3 o2 housing, but the gasket was covering up a good 1/4 inch of the wastegate hole in the turbine housing!!! The worst part was that it was covering the side that the flapper opens up to, so the exhaust gases were shooting straight into a wall, basically. Well when we pulled off the gasket and looked at the underside, you could easily see what I was talking about. about 3/4 around the wastegate hole was black, about a ~1/4 inch big! This was obviously not going to work, so we busted out the dremel and carbide bit and went to town on the gasket! It was easy to see how much needed to be taken out, since the black created from the exhaust pummeling into the gasket made a nice line that showed exactly were it was. After 45 minutes of grinding, we got it to the size of the wastegate hole, perfect.

It was amazing how much the gasket was covering up the hole, and the fact that it was covering the part of the hole where the flapper opened up made it even worse. I'm really surprised we didn't notice this when we put it together last weekend.

Now, we haven't been able to put everything together and see if it's fixed because we have a broken exhaust mani-to-head stud that needs removing and a new exhaust mani-to-head gasket to put in. However, that's tomorrow's job and we should be finished by early evening tomorrow! I'll let you know how it goes!