Actuator/Wastegate spring release issues

[mr299ron]

Right, I have turned a couple of threads into what the title suggests so I'm going to compile it all into one thread so it's easier to track.

So the issue at hand is:

Cold engine boost is 5PSI

Warm engine boost is 8PSI

----

Now, when the engine is cold, the vsv will stay shut and and so limits boost to wastegate pressure at 5psi in my case, and 7psi in the manual 20 years ago.

When the engine is warm the vsv opens and relieves pressure from the wastegate to allow more boost and powaa, but this is only at 8psi. However, it is a 3psi increase over cold pressure. So the VSV is inturn working correctly and the car has no knocks etc as boost is increased by the vsv because the ECU is happy and thus opens the vsv.

What could be the problem here?

Could it be a weak spring that is allowing air out of the wastegate thus making it harder for the turbo to create boost cold and warm?

Could there be just crap in the wastegate and vsv lines?

Could an MBC solve this by essentially controlling when to release pressure?

However, if the wastegate spring is broken, upping the boost shouldn't have any effect right?

Could one of my cats be clogged thus preventing a decent flow?

I think I'm fairly close with my analysis/troubleshooting/research, but I would just like someone to confirm my issue put into my own words.

[danjama]

Wait until you've got the MBC installed and report back.

[mr299ron]

But could you please confirm for me how this could solve the issue if the wastegate is faulty?

[mr299ron]

Come to think of it if the wastegate spring is loose then I should be making more boost as the air is being allowed to escape, which is its usual job once the vsv tells it to open, thus the being able to create more boost. When the car warms up, the vsv clearly opens and gives me another 3psi, but only to 8psi from 5.

So I wouldn't me making less boost if this was loose, but rather more as it's essentially doing its job but when it shouldn't be. So I don't think it's a loose spring anymore, or the spring at all.

I reckon its the catalytic converter. To my understanding, clogged cats can restrict output, and thus flow, therefore limiting boost. This might explain 5psi on wastegate pressure.

Luckily I'm getting the cat replaced with a decatted downpipe on wednesday, so we will see if this helps. I will fit the boost controller afterwards.

Let me know if you guys have any thoughts.

[markstevieandmads]

Same question same answer
Faulty vtv so replace with MBC.

[tiff_lee]

A weak actuator would mean the wastegate opens sooner therefore making LESS boost.

Clogged cat would affect power but i doubt it would ever be restrictive enough it would actually stop the turbo spinning up enough to generate boost, in fact the car would probably struggle to run if that were the case.
Besides as you say youre making 8psi when warm so no reason the cat would prevent you making 7 when cold.

[parker455]

I will sell you a VTV valve for £13 delivered.

[mr299ron]

Ok cheers guys I'm just trying to understand how it all works.

Ah okay, so the wastegate opens to regulate boost, so if it's opening earlier then the boost pressure is being regulated prematurely. I for some reason thought it worked the other way :S But how would an MBC cure this? Is it because you can set the pressure yourself which therefore tightens the spring?

I've seen a thread where replacing the cat actually worked and his issue was similar to mine. If you have a clogged cat you would be restricting flow and therefore power and therefore how much the turbo spins as the turbo spins due to the amount of air being generated. Less air being generated, less it spins. Maybe anyway, I'm just gonna have to wait until wednesday.

Parker - don't try and mug me with a vsv I'm getting an mbc and you know I am

[tiff_lee]

Ok cheers guys I'm just trying to understand how it all works.

Ah okay, so the wastegate opens to regulate boost, so if it's opening earlier then the boost pressure is being regulated prematurely. I for some reason thought it worked the other way :S

Yes hence why I posted

"Just to clarify (disregard the vsv for a moment), boost pressure is controlled by the wastegate actuator, once boot pressure reaches the required pressure to overcome the spring inside the actuator it will move thus opening the wastegate and regulate boost. This is how boost is controlled when cold and the vsv shut.

The vsv operation is nothing to do with boost creep or boost spikes, those are two different phenomenon which can occur with turbo setups.
So when 'hot' the VSV is open, by bleeding off a small amount of air (via the VSV) a higher boost pressure is now required to overcome the actuator spring (needs to compensate for the loss in pressure via VSV).

I'm not sure if people run a mbc with the VSV still connected or not as i'm new to 3SGTE engines (had c20lets before) but if you were to remove it from the boost control circuit and just use a mbc then whatever you set that to is what you will get. Depending on whether you use a bleed valve type or dawes device (ball and spring) you may get a boost spike then if setup wrong."

in your other thread.

I've not seen the stock actuator on a 3sgte but on the gucci ones you can buy it's possible to replace the spring inside, so a stronger spring would need more pressure to overcome it hence a higher boost pressure. Just as a weaker one opens earlier so less boost.

[2mad]

Mate i dont want to be a dc1k but this is like no.4 posts on the same subject .. fit an mbc and go from there, i did this and sorted the problem ... the vsv is a jet that opens when the engine is warm enough .. if its clogged up you wont boost proper .


Sorry again really am trying to help

[mr299ron]

The VSV works, as is why I get a difference of 3psi between cold and warm. It's noticeably different and I know it works. It must be a weak spring as air is being able to escape/be regulated prematurely.

Sorry 2mad, I'm just trying to gather as much information as possible I'll calm down for now..

[2mad]

Just want to see you happy mate

[mr299ron]

I am Look so happy (when I get more boost)...

[tiff_lee]

The VSV works, as is why I get a difference of 3psi between cold and warm. It's noticeably different and I know it works. It must be a weak spring as air is being able to escape/be regulated prematurely.

Sorry 2mad, I'm just trying to gather as much information as possible I'll calm down for now..

Yep, weak actuator causing low boost when cold.

As said though get an mbc fitted then reassess the situation although you probably won't need to as your problem will be solved.

I can see it now, "Too much boost engine blown!!?"

[2mad]

I am Look so happy (when I get more boost)...

Hha ow yes boost is great .. fit an mbc , plug the vsv actuator port .. and enjoy some boost mate .. your next posts will be on fcd's

[mr299ron]

I am Look so happy (when I get more boost)...

Hha ow yes boost is great .. fit an mbc , plug the vsv actuator port .. and enjoy some boost mate .. your next posts will be on fcd's

Hahaha too right! Nah, I'll try bother another forum

[mr299ron]

Update:

Fitted the MBC.

God damn that VSV pipe from the wastegate was an absolute cow to get off. But a few grazed fingers later it's installed.

And now I'm hitting 10 psi

However, I'm pretty sure I have the nut wound all the way out (lowest setting) and I'm hitting 10 and not wastegate pressure, which is what I thought I would hit at first?

Anyway it has pretty much solved the issue and I can't thank you guys enough for 1 putting up with me and 2 helping.

Thanks a lot

99ron

[2mad]

Glad your happy mate .. im running 0.8bar and its wound all the way out lol .. lots of scope for turning it up

[mr299ron]

Yeah I think it's something like 10-10.5. Feels great though, the car actually pulls to about 6k instead of just plateauing at like 4k and just taking me to 6.

Cheers bud you were a massive help.

[tiff_lee]

However, I'm pretty sure I have the nut wound all the way out (lowest setting) and I'm hitting 10 and not wastegate pressure, which is what I thought I would hit at first?

Nope, your wastegate won't see any pressure causing it to move until your mbc reaches the set pressure (assuming a ball and spring type).