Single Turbo Setup Can't Reach Wastegate Pressure

[Arrtus]

Hey guys,

I originally had posted this in the N54Tech forum but got little to no help. I'm really stuck on and can't understand what is causing this problem.

This is a brand new DR700 setup and ever since making the swap, I am unable to reach more than ~9 psi (14 psi spring). The car is obviously way underboosting and I have no idea why. All the vacuum lines have been checked and are brand new. I have pressure tested from the turbo output all the way to the charge pipe and have found no issues. I also tested the compressor housing side of the turbo (and intake) and it did not leak whatsoever. I went through all the V-band connections and everything is on correctly and tightened to the max.

Symptoms: The car sounds different. I don't know if it's because of the single turbo but when going on WOT it doesn't sound like it's spooling. It's also very loud, like it just changes sound as soon as it starts building pressure.

With other maps, the wastegate (I think?) starts pulsing and sounding like it's hitting a rev limiter or 2-step while it's on WOT. It's most likely because of the mac that it's switching the air into the wastegate but it's not able to hold pressure or something. With maps aiming at higher PSI, it reaches ~12 PSI. What would cause the wastegate to do this? Can it be defective? It's a turbosmart gen V 45mm. I also checked the wastegate by putting some pressure on it and I can hear it open and closing. The MAC solenoid is also working just fine (which doesn't matter since it's not in use in map 0 and the problem is still there).

Log of a map 0 pull attached. Any advice or suggestions would be really appreciated!

 

[martymil]

Its got nothing to do with your mac solenoid, disconnect it and test if it hits spring pressure.

It won't overboost as the spring will open at around 12 psi if its the 14psi spring.

Having the electronics connected will only interfere with testing the mechanical side of your system.

You can't hurt it with as the boost is to low.

 

[Arrtus]

Its got nothing to do with your mac solenoid, disconnect it and test if it hits spring pressure.

It won't overboost as the spring will open at around 12 psi if its the 14psi spring.

Having the electronics connected will only interfere with testing the mechanical side of your system.

You can't hurt it with as the boost is to low.

Tried that yesterday. Left the top port open and only ran the reference to the bottom port. Still only hit 9 psi.

 

[martymil]

Disconnect the mac solenoid as your still adding boost under the wastegate diaphragm which will help open the wastegate and won't let you hit spring pressure

Just unplug the mac solenoid electrical plug, it won't give you any errors and leave all the boost lines connected

 

[Cruizinmax]

Disconnect the mac solenoid as your still adding boost under the wastegate diaphragm which will help open the wastegate and won't let you hit spring pressure

Just unplug the mac solenoid electrical plug, it won't give you any errors and leave all the boost lines connected

This is false. I'm not sure why I have to keep saying this. The Mac solenoid cannot ADD pressure to the bottom of the wastegate. It can only restrict or redirect it to the top port. Again the Mac solenoid can only RAISE boost beyond spring pressure.

 

[martymil]

By adding boost to under the diaphragm and having the top port totally disconnected like he did will reduce the the spring rate of the wastegate.

The way he has it plumbed and top port disconnected, we had this issue on our single turbo kit when the top hose pulled out of its fitting and we had all
sorts of under boost issues until I found it, just ask V8bait how much trouble we had when he was tuning it.

How hard is it to disconnect a connector and leave the plumbing intact to run a test.

 

[Cruizinmax]

Tried that yesterday. Left the top port open and only ran the reference to the bottom port. Still only hit 9 psi.

I have seen multiple cases of restrictive intercoolers causing boost drop. If you're getting 14 psi at the turbo compressor housing but have a restrictive intercooler, you may only see 9 psi at the throttle body. Any chance there could have been a rag that fell in the intercooler? Lol.

There's no downside to getting your boost reference from the intake manifold if you're hesitant.

 

[martymil]

Anything is possible, If I had the car I'd find the issue in no time.


This is the problem with internet diagnosis.

 

[135i2]

First thing v8bait got me to do when diagnosing boost issues was to disconnect the mac and run a spring only tune. Then we were able to trouble shoot from there. One issue at a time until problem or problems found.

Martymil worked from the ground up, methodically to check all basic work and keep the system as simple as possible before adding more issues to check such as mac, boostbox etc. The secret to finding the problems were a great tuner and someone who knows their shit.

No rags in my kick arse IC. Just a buggered mac and some oil hydrolocking the WG from early catch can / oil / air separator setup issues.

 

[Arrtus]

Okay, got the charge pipe from ER and it's not leaking like the previous one. Everything past the turbo is completely leak free now. Unfortunately, that didn't solve the issue. Still hitting 10 PSI max at 4500 RPM.

I unplugged the MAC as suggested and drove around but that didn't make a difference.

Seems like what it comes down to would is either:
a) the turbo is working fine but the wastegate is not working properly which somehow causes it to open early and not be able to close with the MAC controlling it

b) there is a leak on the hot side of the turbo, either turbo to header, or header to block, which causes the turbo to not be able to make boost

I'm thinking it's most likely the manifold to turbo connection still so I guess I got some work to do this weekend.

 

[martymil]

Like I said it's not the chargepipe, I very highly doubt the connections are leaking because you would hear, smell and see it if you looked at them period.

I'm certain it's one of these 3, they have not installed the correct spring or the waste gate is faulty or the vband connection is ovalised not letting the wastegate operate properly.

 

[Arrtus]

Like I said it's not the chargepipe, I very highly doubt the connections are leaking because you would hear, smell and see it if you looked at them period.

I'm certain it's one of these 3, they have not installed the correct spring or the waste gate is faulty or the vband connection is ovalised not letting the wastegate operate properly.

I doubt the spring is wrong but even then it should stay closed with the use of the MAC.

How would I be able to see if the WG is faulty? it opens and closes perfectly fine when I use the air compressor. I will check it once more when I take it off again.

 

[martymil]

check it with a compressor when its bolted down on the outlet.

dude if its opening and not letting it go past 10psi its only two things wastegate not working properly or wrong spring.

Its not that hard to check both of these before you start ripping things apart.

put an 18 psi spring in there and see what happens, maybe the spring is fucked.

This is by far the easiest thing to check and test, how come you havent done it yet ?

the simplest things are usually what is causing the problem.

 

[Cruizinmax]

You had said leaving the pressure reference off the wastegate it will hit over 10 psi. That tells me it's not a lack of exhaust pressure to make more boost. So not a exhaust leak.

I suspect either wrong spring in the wastegate or a restriction in the intercooler and the fact you are still getting your pressure reference pre intercooler.

I suspect I'll never know since you won't check either of those things. I'll bow out and let others try to help. Seem like too many cooks in the kitchen.

 

[Arrtus]

You had said leaving the pressure reference off the wastegate it will hit over 10 psi. That tells me it's not a lack of exhaust pressure to make more boost. So not a exhaust leak.

I suspect either wrong spring in the wastegate or a restriction in the intercooler and the fact you are still getting your pressure reference pre intercooler.

I suspect I'll never know since you won't check either of those things. I'll bow out and let others try to help. Seem like too many cooks in the kitchen.

Well I took off the wastegate today and I guess it still leaks? Has carbon all around the inside of the clamp and a small amount between the flange.

I looked over the log I did when it boosted over spring pressure but it still did it extremely late in the RPM. I attached the log of that if you still care to take a look.

I will take off the intercooler tomorrow and check it but I highly doubt there is anything in there. I remember washing it thoroughly before installing it when I was putting the engine back in the car.

The spring in the wastegate is red in color which actually doesn't seem correct for the wastegate that I have... looking at the datasheet, it should be a blue spring. Apparently the red color is a 14 psi spring for WG40 and blue is for WG45.. Looking at the other springs that came with it, they are all the wrong colors.. pink, brown, black.. all for WG40.

So... yeah... I guess I'm reaching out to Turbosmart to see what the hell is going on.

 

[martymil]

I wouldn't be worried about the the wastegate leaking because you have the wrong spring.

Are you sure you have a 45 and not a 40, measure the inside diameter not the outside.

 

[martymil]

you can also try adding the black spring see if that helps till you get the correct spring

 

[Arrtus]

I wouldn't be worried about the the wastegate leaking because you have the wrong spring.

Are you sure you have a 45 and not a 40, measure the inside diameter not the outside.

Yes, it's definitely the 45. Just measured it too. The 45 looks different from the 40 as well.

They must be physically the wrong springs even if they're rated at the same PSI.

Thank you for your suggestion, my stubborn ass wouldn't have opened it up if it wasn't for you. Would have never thought that they came incorrect.

Edit: Will try adding the black spring and test it tomorrow.

 

[Zulu]

Did you ever figure out what your issue was? I’m having the same exact issue as you with my BigBoost 3.4 M235 except I’m running a TS ultragate38 GenV with the red 14 psi spring. According to TS’ spring chart, this is the correct spring for my gate. Seeing 7psi at 0-10% duty on the EBC and 17psi at 100% duty.

 

[Arrtus]

Did you ever figure out what your issue was? I’m having the same exact issue as you with my BigBoost 3.4 M235 except I’m running a TS ultragate38 GenV with the red 14 psi spring. According to TS’ spring chart, this is the correct spring for my gate. Seeing 7psi at 0-10% duty on the EBC and 17psi at 100% duty.

Unfortunately, I did not. I never understood why when I increase the spring pressure, I'm able to raise the boost slightly but still not reach the rated wastegate spring pressure. At the same time, I can hear my wastegate fluttering when I get into boost; meaning that it is able to rapidly open and close while still not reaching boost.

The only thing I can think of is the wastegate flange still being the issue. Talking to TS and DR, they both had said it would not cause that big of a boost leak. I am planning on taking the car apart this weekend and sanding down the flange as much as I can to see if that makes any difference.

It definitely sounds like you have a boost leak if you're hitting 7 PSI on a 14 PSI spring with 0% duty cycle. Have you already done a boost leak test?

 

[SLOWESTN54]

Unfortunately, I did not. I never understood why when I increase the spring pressure, I'm able to raise the boost slightly but still not reach the rated wastegate spring pressure. At the same time, I can hear my wastegate fluttering when I get into boost; meaning that it is able to rapidly open and close while still not reaching boost.

The only thing I can think of is the wastegate flange still being the issue. Talking to TS and DR, they both had said it would not cause that big of a boost leak. I am planning on taking the car apart this weekend and sanding down the flange as much as I can to see if that makes any difference.

It definitely sounds like you have a boost leak if you're hitting 7 PSI on a 14 PSI spring with 0% duty cycle. Have you already done a boost leak test?

Did you ever try swapping wastegates with a new one, incase yours was faulty from factory?