help hella low boost!

[1gEvoSmasher]

I have an entirely stock 91 talon tsi and i just installed an MBC the other day however it kept running stock boost on it, i didnt worry it was only 10 bucks, today i noticed the boost drop from 8psi to about 4psi. i dont know what caused this problem. maybe a not so bad boost leak became a really bad boost leak. i can hear the turbo spooling up really really loud now.

 

[cruisintalonawd]

boost leak maybe. Your not going off the stock gauge are you?

 

[cookmeup272]

$10 boost controller? what kind is it and where did you get it?

 

[1gEvoSmasher]

it was off of the DIY mbc with the brass fittings spring an ball. but it ran fine for a few days with it on there so im guessing it must be a boost leak. because i feel like it takes forever to build pressure even though it only goes up to 4psi and yes i have aftermarket gauge

 

[DSMDriver69]

Its probably just a boost leak. And as asked before please tell me your not going of the stock boost gauge. On the other hand I know the DIY mbc's work i just don't know if I would trust them for a long period of time.

 

[1gEvoSmasher]

yeah, im having trouble finding the boost leak. and its driving me nuts because i can drive it but its slow as hell! (but sounds really cool )

 

[LiquidX]

Do a complete boost leak test starting at the throttle body. Use a spray bottle of dish soap and water and look for the bubbles. Change out all the vacuum line and zip tie the ends to be sure there are no pin holes and they are on the fitting securely. Once you are sure there are no leaks in the throttle body, gaskets, intake manifold, injector seals and vacuum line connections contine on. Work back to the intercooler and check the peressure there and be sure the BOV is staying closed. Finally start it at the turbo to be sure it's holding at least 25 psi in the system.

Make sure you bypass the MBC while doing the testing and that you keep your BOV recirculated when you are finished and driving around.

 

[99gst214]

I dont know if i would trust a $10 mbc. But either way just see what a boost leak test does and go from there. Also recommend getting an aftermarket boost gauge, even if its just a cheapy sunpro or something.

 

[banshee88]

Blt!!!!!

 

[400hp93talon]

Every boost leak I have encountered which there has been alot has made my car hella overboost. I dont think its a boost leak I think your waste gate is junk and it's possibly stuck wide open or broken which would cause it not to build boost. Becuase if wasn't opening at all your car would overboost so the complete opposite occurs when its stuck open and it would sound like its builing boost but in fact wouldnt. Thats my theory.

 

[1gEvoSmasher]

thats an interesting way to look at it. i would think however a boost leak drains pressure but the wastegate is ###### something i should look into.

 

[Red97Eclipseboy]

Even with a boost-leak, any that I've ever seen in anyones' car, boost still hits its target-level. The turbo just over-spins like crazy to achieve the given PSI. I agree on checking your wastegate, or that MBC is junk.

 

[belize1334]

If it is a waste-gate issue, since you're underboosting instead of overboosting you can be sure that the waste-gate is opening too soon rather than too late. You can also forget about the mbc being the problem. There's no mbc in the world (functional or otherwise) that will cause a wastegate to open below the factory boost level. You can use them to raise boost but never to lower it. First thing is to make sure that the wg isn't opening to easily or stuck open. If you look down at the turbo you can see where the wg actuator attaches to the wg arm on the front of the turbo. You'll be looking through a "window" in the lower heat shield and you should see a cotter pin holding things together. If the two pieces have come apart (possibly due to a broken or lost cotter pin) then the wg arm would swing freely and that could explain your issue. It's also possible that the spring in the actuator broke and isn't applying enough pressure to hold the arm shut. I've never actually heard of this happening but it is possible.

If it's not the waste-gate then there are a number of other possible explanations.

1) Turbo is dying. Pull off the intake pipe and see if it spins freely. Make sure the car isn't running cause you don't want to slice off your finger tip.

2) Massive boost leak. Regardless of anecdotes about boost leaks causing overboost, a big enough boost leak will cause low boost pressure at the manifold. Imagine a boost leak so big that you don't even have an intake pipe on the throttle body. Do you think you'd see overboost or no boost?

3) BOV disfunction. Check to see if your bov is hooked up correctly. If for some reason the signal line were disconnected then it'd just be open all the time and you'd get little to no boost pressure.

 

[1gEvoSmasher]

i had a few buddies of mine who know dsms very well look at it, one of which has had 3 or 4 and we have figured that its the wastegate. and whats happening is the turbo is spooling up but none of it is getting pushed into my system the flapper is stuck in a position cant remember whether its open or closed but its causing me to have none of my boost but a hella awesome sound . luckily my friend has an extra 1g wastegate lying around that i can play with so basically i gotta be nice to it till its put in then its boost time!

 

[Red97Eclipseboy]

If it is a waste-gate issue, since you're underboosting instead of overboosting you can be sure that the waste-gate is opening too soon rather than too late. You can also forget about the mbc being the problem. There's no mbc in the world (functional or otherwise) that will cause a wastegate to open below the factory boost level. You can use them to raise boost but never to lower it. First thing is to make sure that the wg isn't opening to easily or stuck open. If you look down at the turbo you can see where the wg actuator attaches to the wg arm on the front of the turbo. You'll be looking through a "window" in the lower heat shield and you should see a cotter pin holding things together. If the two pieces have come apart (possibly due to a broken or lost cotter pin) then the wg arm would swing freely and that could explain your issue. It's also possible that the spring in the actuator broke and isn't applying enough pressure to hold the arm shut. I've never actually heard of this happening but it is possible.

If it's not the waste-gate then there are a number of other possible explanations.

1) Turbo is dying. Pull off the intake pipe and see if it spins freely. Make sure the car isn't running cause you don't want to slice off your finger tip.

2) Massive boost leak. Regardless of anecdotes about boost leaks causing overboost, a big enough boost leak will cause low boost pressure at the manifold. Imagine a boost leak so big that you don't even have an intake pipe on the throttle body. Do you think you'd see overboost or no boost?

3) BOV disfunction. Check to see if your bov is hooked up correctly. If for some reason the signal line were disconnected then it'd just be open all the time and you'd get little to no boost pressure.

Well, over-boosting and target-boost still happen with boost-leaks, sir. I don't care what you say. And the fact that you had to resort to the highlighted to explain your "help" speaks volumes.

 

[400hp93talon]

I wasnt thinking when I made my last post. Leaks in your Vaccum lines will make a car overboost how ever a cracked coupler,leaking intake manifold gasket and so on can cause your car to not make as much boost so they are Two seperate kind of leaks and I wasnt thinking.

 

[LiquidX]

Regardless of all of this back and forth, do a complete boost leak test like I described AND disconnect your wastegate flapper from the actuator arm to be sure it's allowed full free movement. After that, hook a pressure source up to the wastegate directly to see it the arm moves (hooked back up to the wastegate flapper yet?) without catching or binding on the housing.

Both can have the same symptoms; turbo will work harder to make set boost levels but still leak a lot of air or very low boost will be attained. One being that most of the exhaust is bypassing the turbine which will reduce the boost levels and another being multiple boost leaks that are overall bad enough to lower boost levels.

When I first boost leaked my car, I was able to reach 20psi with my compressor but all the air would leak out in a second or so. Your's could be worse or your wastegate isn't working properly however, I have been able to disconnect my wastegate off my E316G BEFORE porting and would still see PSI over 20 on my gauge.

Either way, perform both steps to not only be sure the wastegate is functioning properly and not causing your low boost, but to be sure that you ALSO don't have any boost leaks which will hinder your cars performance and possibly shorten the life of your turbo. It's all part of the maintenance routine.

 

[standard235]

If it was a boost leak, wouldn't the MAF be seeing a lot more air than 4psi's worth, and hitting fuel cut? Sounds like the wg is stuck open.

 

[6boltpower]

im having problems with my car also, i was driving around after i got it fixed hitting fuel cut at aroun 16 psi. i have mods such as hks bov, 16g turbo front mount intercooler, etc,then i noticed driving on the interstate crusing at like 70 -80 it was bogging out sounding like a loud pos. i cant go up any hills without it dieng out. or anything unless i down shit to like 2nd gear and beat on it in every gear, then today i got my recirc fitting for my bov, i was going to advanced to buy the hose for it. bought the hose and on the way home i noticed i no longer get any boost above 6 or 7psi. no power at all and still bogs.. and it takes awhile for it to get to this 6 before when it was atleast hitting fuel cut it would spike up really quick oyeah 3inch turbo back apexi exhaust, slowboy racing cast mani.. any ideas? the plugs have been changed and regapped and changed thought that was the problem at first.. WTF

 

[1gEvoSmasher]

Replaced wastegate and still nothing........ Anymore ideas? while replacing wastegate i checked the turbo for shaft play, it was very very solid so thats ruled out.

 

[1gEvoSmasher]

i think i have it figured, pulling turbo on monday to seal it up