My GVR4 Suddenly Not Boosting PAST 10PSI!! Any suggestions???

For the past few weeks I did not do any modifications to the car, if anything not even drive it. Recently i noticed that the car would not past 10psi, i figure ok vacum leak since my egr is removed. I recap the vacum ports on the TB. and still nothing... My vacume on the boost gauge is around 20 at idle. I removed the line from the waste gate to MBC still not passing 10. I removed the line from jpipe to MBC... still nothing. Mind you the car was running on 15 lbs for over a year. Any suggestions??? Thanks guys!

 

[AnotherNewb]

Major boost leak or turbo failure. Dbossmans VR4, when he first bought it didn't smoke, but it didn't boost either. Pulled the turbo to find so much coking that it pushed a plate into the turbine wheel. Pull your intake off and see if the wheel spins freely.

 

Nope no shaft play, turbone moves freely.no boost leak, car holds 10 strong up top without breaking up..can it be actuator arm?

 

[solidviper89]

Exhaust leak before turbo?

 

Nopee.... Any other ideas????

 

[ercp98]

hi, does it buck or hesitate when it gets to 10 psi? just wondering because i am trouble shooting
the same issue and i have done some of the steps you have with no results.

 

[Terry Posten]

I bet the wastegate is not closed all the way or you have an internal crack in the hots ide of the turbo.

 

Okay so I took the actuator arm off the flapper, tried pulling it. It moved a little about an inch I would say,but still samething.....even made bov softer...

 

[Hertz]

You're running around on wastegate spring alone an wondering why it doesn't go over 10psi?

 

[moidsm1]

I had a similar problem before. It was a crack in the wastegate flapper area. The flapper would be closed but because of the crack, hot gas would still pass thru not letting the turbo build boost. The only way you can find if this is your problem is to remove yout 02 housing and visually inspect that area.

 

[belize1334]

Quoting Hertz:
You're running around on wastegate spring alone an wondering why it doesn't go over 10psi?



Yeah lets have some clarification on your current configuration. Are you running with a boost source straight to the wg or are you running with the wg completely unplugged? Does it build right up to 10 and then hang there or is it slow in building boost?

 

Two different times i removed each line. First i removed the line from my jpipe to the MBC, a few months back this line from the MBC to the jpipe was orignally on the P port on the intake manifold after i Installed my FMIC, therefore it would spike to 20psi. I figured yesterday let me disconnect this line from the Jpipe to MBC and the same ordeal would happen if it was not the wastegate being the problem and it would spike to 20+psi. But it did not. It just builds boost quickly to ten psi.

From a stop, it builds boost quickly to ten, even till about 6500 rpm it still stays at Ten psi, as if their was some sort of limit on the turbo. Even in second gear from a roll it spools quickly to 10, the car pulls but then when it peaks at ten it just feels like it wants more.

 

[belize1334]

But you're still not being clear about what lines, if any, are connected to the wastegate itself. The waste-gate actuator has a port on it that you run your boost source too (via a MBC, ebc, or just straight line for wg pressure). Disconnect that line so that there is NO signal going to the wastegate. Then go out and roll on the throttle and see if it goes past 10psi. If everything is working right this is identical to maxing out your MBC in which case it should spike to has high as 30psi or so and drop off to about 21psi or 22psi by redline. Obviously you'll want to let off before it gets that high...

If with the wg completely disconnected you still can't break 10psi then you've got a real problem. Either the exhaust route isn't providing a sufficient pressure differential to spool the turbo...or you have a boost leak. If it's the exhaust route, then there are 3 likely causes. Your exhaust could be SUPER CLOGGED so that you have mega back pressure and you can't spool. You could have a MAJOR exhaust leak pre turbo. Or you could have a big crack in your compressor housing which is negating the wg flapper arm. It's also possible that the wg actuator is somehow messed up and the wg arm is swinging open of it's own volition. But, any of these issues should also cause it to spool slowly to 10psi. The fact that it spools up quickly seems to imply that your vacuum hoses are hooked up wrong.

 

Belieze1334, Sorry for my horrible explanation. Your first paragraph in your last post is exactly what I did. I Disconnected the MBC from the Jpipe which shouldve caused the turbo to spool into the 20 psi range easily but it did not.[ I know before my line was off and it did that a while back].

2] I then disconnected the line from the WG to the MBC, same affect.

3] I even disconnected both lines at the same time and same effect.

Yes it spools quickly to 10psi, I checked for any leaks pre turbo but did not find any.

I recently about three months ago installed a hiflow cat.

The car is quieter then normal though..

 

[belize1334]

Ok, now we're on the same page. So you've COMPLETELY disabled the wg-actuator and you're still not going past 10psi.

Heres another test. The wg-actuator has a throw-rod which connects to the wg-arm via a cotter pin on the front of the turbo. You sould be able to access it through a "window" in the heat shield directly in front of the turbo about 2-3 inches below the manifold to housing flange. Pull the cotter pin and then pull the rod off of the arm. It'll be under tension so you'll have to pull toward the drivers side and forward to relieve the tension and disconnect the arm. With that done your waste-gate will swing freely open. Now go do a pull and see what happens. You should get 0psi up to about 4k rpm and then it'll rise (notorious boost creep) and keep rising. On my 16g it rises to about 15psi by redline. Lets see what your does.

 

Yes I did pull the pin off from the actuator arm but did not drive with the pin off. So you want me to take the arm off the actuator and drive with it OFF correct?

 

[belize1334]

Correct. This will tell you the minimum boost that you can run throughout the rpm range. Now, I realize that you're trouble is running more boost and not less...but as a diagnostic tool it could be illuminating.

 

Roger Quick question, if I remove the arm how is the flapper going to open? Doesn't the arm open the flapper?

 

[ercp98]

the flapper would just flap close / open. that is why it would not build boost because you are dumping the exhaust out through.

 

[belize1334]

The arm doesn't open the flapper. The arm holds the flapper shut until desired boost is reached and then lessens it's grip allowing the exhaust to push the flapper open. By removing the arm you free the flapper to swing open as it pleases.