In what way an Evo IX turbo can be broke and build boost? I mean is there anything that can be broken on the turbo, other than the wastegate "door" that release the air, that can cause boost increasing as the rpm increasing?

I tied the wastage open so the turbo won't spool at all....and the boost was something like 7PSI.
Is it back pressure? Something is wrong with the turbo or what you guys think?

 

A turbo will still make some amount of boost even with the WG fully open so that's not so much of an issue. The other thing you are describing just sounds like boost creep which is a result of the WG not being able to flow enough and keep up with the amount of exhaust that needs to bypass the turbine. Often with an internally gated turbo you will see this when you run an exhaust with very low back pressure (eg. a straight pipe or dump). It would help to know what you have on the car and if the issue came on suddenly with out warning or if you changed your setup and now have the problem

 

My car is stock engine and turbo. Hks RS intake filter, Greddy BOV, Tomei turbo elbow and downpipe kit, Greddy exhaust (without catalytic), Fuel pump 300lph, Grimmspeed solenoid valve.

Aggree on the fact that turbo will still make some amount of boost even with the WG fully open, but 7PSI?

Issue came without warning. Actually I left the car at the shop for custom IC piping. I guess if IC pipes have some leak car would have low boost issue not over boosting.

I don't think is boost creep either since the car is building the same boost with the forge wastegate and stock evo IX WG. I also disable the solenoid and connect the boost directly on the stock and forge WG.
I also checked the exhaust and it is clean....just to eliminate exhaust back pressure issue. I am about to remove downpipe and check the turbo elbow also.

Tuner also checked the rom and he said no way, rom is fine.


What else do I have to check? Really strange!

 

so?

 

Yeah, 7-8 PSI with the WG wired open sounds about right. What are you trying to prove?

Back in the last century I had a Buick GN. We installed a Myers TE-50 turbo onto it, which was a Garrett T04E variant with a clipped H2 turbine wheel and the thing would boost to 20 PSI with the integral WG puck wired open. So, eventually we had to run an additional backup gate flanged onto the exhaust crossover pipe.

We had tried everything including porting the byoass port and installing a larger diameter PT&E WG puck but the single internal gate couldnt vent enough exhaust gas to get it below 20#. So, we had to add a second(external) gate in addition to the integral gate.

 

Why do you mention boost creep? What OP described is not boost creep.

 

I am not trying to prove, I am trying to find out why the car is boosting 17.5PSI when is tune for 11PSI and boost goes up as RPM goes up!

-I thought was the forge WG issue so I put the stock WG back. same boost issue
-I checked the the turbo elbow,downpipe and exhaust for back pressure, but no problem with those.

Does anyone know if boost can be build up when engine has lots of exhaust gas? I don't know how to explain it. Can the boost increasing due to the fact the AFR is wrong? I mean if lots of exhaust gas (from exhaust manifold) are going back to turbo, could make the turbo continuously boost?

 

lol....I google those car's you mention above, never heard of.........wow great cars!!

any idea about the boost issue here?

 

Who ever finds the solution wins

So, the issue here was that the car suddenly instead of 12PSI was boosting up to 18 so I was off the the throttle.
After I had me car checked by the tuner, checked the exhaust, the downpipe, the solenoid, the wastegate-and the actuator, changed some hoses and I found out the everything was perfect I decided to go WOT with alt map which suppose to boost at 22PSI (26 overboost). I was prepared my self that if the car was about to overboost more than 26PSI I would left the throttle immediately.

Guess what? The car boost normally up to 26PSI tapper to 21PSi at some point. No issues with the alt map!

Who's fault you think is, when the car instead of 12PSI it will keep boosting as the RPM are increase????????

 

What else do I have to check...anyone?

 

I may have misunderstood what he was saying, my impression on the first problem was he set the boost and as RPM's increased the boost was going past that predetermined level which is indeed boost creep.

 

what's really strange is that your concerned about making 7psi of boost with a turbo that is designed to supply ~16/20psi on a 2.0L engine?

the exhaust gases have to exit the engine & they will visit the turbine wheel regardless if the small flapper is wired open.

I cant believe i wasted keystrokes for this post.

 

The rule of thumb for wastegates is as follows, for high boost you want a small WG and for low boost you want a large WG, obviously that is a black and white scenario with a big gray area in between but that's why there are different sizes of gates available.

In your case when you are trying to run low boost (such as 12psi) you do not have the flow capacity to divert enough exhaust around the turbine to maintain that lower boost. The car is handling the higher boost map because the internal gate can flow the appropriate amount of exhaust since a majority of the total amount is used to power the turbine. The actuator itself does control boost when adequate flow is available but the size of the opening through which the exhaust passes is the limiting factor in certain cases.

To make an analogy; If you are trying to blow through a straw (WG opening in this case) as hard as you can there will be pressure built up in your mouth causing your cheeks to puff up(excess boost) since the air cannot escape fast enough, where as if you are blowing through a paper towel tube you will have no pressure build up and can control the amount of pressure in your cheeks by blocking/unblocking the end of the tube(Function of the WG actuator)

 

First of all I am not concerning about making 7PSI boost with the small flapper wired open. I just asked if its normal.
What I am asking is, why the car now is boosting 17-18 psi, after piping system installation since before that it was boosting 11-12 psi!?

By the way I am really sorry for your wasted keystrokes on this post.....really wasted keystrokes. Next time read what have been said previously. Sir!

Thank you anyway

 

WoW! Thank you man...that was great explanation.

Do you think that has to do anything with IC piping installation? Because I am sure that before I put those pipes car could handle both boosts. (low and high boost map).
Now the air is passing through those polish pipes faster, and maybe more air.

So, is there any solution for this? Can my tuner control this pressure?