Is my wastegate too small? Cant stop free boosting

[gt1r]

Hi all just got a new set up put on my car. Brand new genuine mitsubishi TD05 big 18g custom made with 3" v band dump no internal wastegate running a 38mm external and I cant stop the thing free boosting. Ecu is a link g4 boost set at 6psi in ecu. Running a 3 port EBC.

I have tried everything to solve this problem, tried manual boost controller, tried 7psi wastegate spring, every way you can set up the vacuum lines, changed to a different gate and everytime boost shoots up over 30psi (that's all my guage goes to) nothing has made any difference.

All I can think of now is that my external wastegate is too small but it shouldn't be. My question is can I take the spring out of my gate and run it with no spring? If I still over boost then its telling me it is too small and I need to get a bigger one.

Will this damage my turbo at all? Any help or ideas will be a good help Thanks

 

[The Doc]

Sounds possible that the diaphram has split

 

[lakeview]

if your car is not set up for 30 psi id be more worried about the engine and not the turbo

 

[Fast Guy]

How much preload do you have on the actuator?

 

[Makaveli_se7en]

Sounds like your wastegate is not opening at all rather than it is too small.

 

[gt1r]

Sounds possible that the diaphram has split

I have pulled it apart and checked plus change the gate. One was tail other was turbosmart same thing still free boosting

 

[gt1r]

Car is

if your car is not set up for 30 psi id be more worried about the engine and not the turbo

Car is forged and will be able to handle I only get up to able 3500 rpm before buttoning off.

 

[gt1r]

How much preload do you have on the actuator?

I have put a 7psi spring in the gate can open by pushing on it quite easy

 

[gt1r]

That's

Sounds like your wastegate is not opening at all rather than it is too small.

That's what I'm trying to figure out? I have tried everything to see if its opening but all has same result. That's why I'm thinking of taking spring out and seeing what happens. If its still over boost then gate is too small but if I don't get boost then its just not opening. I'm wondering if I will do any damage to my turbo if I run the gate without a spring tho?

 

[The Doc]

If it was too small you would get boost creep which is a differant issue altogether, your wastgate is stuck closed.

 

[The Doc]

38mm wastegates are fine on these cars and used up to 600hp ish on gt35r etc

 

[Fast Guy]

I have put a 7psi spring in the gate can open by pushing on it quite easy

The spring and preload are different things. Normally when you align the hole in the actuator arm with the wastegate rod, you have about half a hole offset (preload) on the too short side. A cheap way to increase boost before all these fancy electric gizmos was to make that distance bigger, say a complete hole offset, so you had to force the rod onto the wastegate, this meant the turbo made more boost to overcome the increased loading and open the wastegate.

I take it your wastegate isn't stuck closed when you say "can open by pushing on it quite easily"?

Try disconnecting the boost line to the actuator at the other end and put a foot pump with a gauge or something on it and see if the wastegate opens when you pump it up.

Is there any leaks in your boost line to the actuator? Where's it run from?

 

[gt1r]

The spring and preload are different things. Normally when you align the hole in the actuator arm with the wastegate rod, you have about half a hole offset (preload) on the too short side. A cheap way to increase boost before all these fancy electric gizmos was to make that distance bigger, say a complete hole offset, so you had to force the rod onto the wastegate, this meant the turbo made more boost to overcome the increased loading and open the wastegate.

I take it your wastegate isn't stuck closed when you say "can open by pushing on it quite easily"?

Try disconnecting the boost line to the actuator at the other end and put a foot pump with a gauge or something on it and see if the wastegate opens when you pump it up.

Is there any leaks in your boost line to the actuator? Where's it run from?

I'm running a external wastegate not internal so no rods or anything. Turbo is custom built with a 3" rear housing so all I can run is a external gate. No leaks all brand new boost lines when I got it tuned. The guy that was tuning my car told me any 38mm gate was too small but I didn't believe that but I'm starting to now

 

[gt1r]

My wastegate vacuum line runs to the proper spot on the intake manifold

 

[gt1r]

If it was too small you would get boost creep which is a differant issue altogether, your wastgate is stuck closed.

Cant be I have tried 2 different ones both are moving freely off the car

 

[Fast Guy]

I'm running a external wastegate not internal so no rods or anything.

D'oh! Missed that somehow.

 

[gt1r]

D'oh! Missed that somehow.

Do you think I can run it without a spring for a test run without doing any damage to the turbo?

 

[keastygtir]

Can you attach a air line to the wastegate and see what pressure it opens up on?

 

[gt1r]

Update I have fixed the problem. The boost source was not working from the factory wastegate vacuum or any over vacuum on the intake manifold. I had to weld a vacuum nipple into the intercooler piping just after the intercooler right below turbo. Was hard to figure out but a easy fix

 

[johnny gtir]

Glad it's sorted and thanks for putting the out come as so many probably guilty myself. Forget once it's fixed to put the result which helps others