External Wastegate Opening at higher boost than spring rated

[Chereboy]

Hey all, I hope this is in the right topic. I've got a 2001 ER34 Skyline.

I've got a question regarding External Wastegates. I've got a Garret GT3076R Turbo and a HKS External Wastegate. I'm currently using a Blitz SBC Boost controller and have had no issue until yesterday. I've had a small boost leak for a couple months now as I've needed to get a small piece of intercooler piping made up. I had the piece made up and installed it and immediately noticed that the car was idling better and I had no rev hang anymore so it was a win. The wastegate currently has a 10 pound spring in it. When I took the car for the 1st drive around the block, it was running better than ever. But as soon as I gave it, I boosted straight up to 30psi before the gate started to open. I know when it's opening as I've got a screamer fitted. The only reason the car isn't boosting any higher is because the car is boost cutting and it's splattering like crazy at 30psi. I previously had the boost controller to open the gate at 15 pound, so I turned the controller off and still got 30psi. I opened the engine bay and Disconnected the boost controller and I still am running 30psi. I haven't got a clue what's happened. Everything was fine, and all I did was just change a short pipe over, did not disconnect anything. 

 

I currently have the controller hooked back up as I've rules the controller out of being the issue. I have the controller hooked up as follows and it was working perfectly fine for around 3 years with no issue 

 

Blitz Dual-DBC Spec R Boost Controller 

 

"IN" on the boost controller to a nipple on the J-Pipe going into the throttle body

"OUT" going into the top of the Wastegate

Bottom of the Wastegate connecting to a 3 way T piece splitter connecting to the Throttle Body

I have it connected to the Throttlw Body because the Turbo does not have a Nipple on the Compressor housing. 

 

As I said, I never had any issue with this current set up, but if it is incorrect by any means, please let me know. 

 

When I Disconnected the Boost Controller and want just Wastegate preasure. I had the Top of the Wastegate connected to the J-Pipe and the bottom of the Wastegate connected to the Throttle Body 

 

Thanks again for any help guys

[BK]

Could be a few things. If your plumbed up wrong that's bad, or have a split in the line to the bottom port that's even more bad.

A split in the line to the bottom port will act like a bleed to your gate raising your boost pressure, as in the gate is getting lower pressure than reality. Check for boost line leaks !

I have had this happen before and with a gate set a 20psi, it cracked at above 30 - all from a split.

Draw a diagram of the setup.

[Chereboy]

Hey sorry guys, I might have left out some crucial information. When I took the car for a drive after replacing the intercooler piping, the hose clamping to the bottom of the wastegate was resting on the exhaust manifold and had a burn slit straight through it, when i grapped it and pulled it abit to have a look it snapped clean in half right in my hand. Im not sure if this might have damaged the wastegate.I had extra hose on hand and changed that over straight away and re-routed it away from the manifold.
The wastegate I have is second hand and ive been running it on my car at 15psi for 1 year and 2 months. Not sure about the previous owner

I also flipped the top and bottom of the wastegate to see if that would somehow resolve my boost issue and i noticed that when I accelerated, the gate was closed and as soon as I let go of the throttle, the gate would open as I would hear the screamer start bleeding out exhaust noise. When the revs dropped back to idle, the gate would close again. I did notice that my boost preasure was staying around 7psi.

Anyways, here is a diagram of the current setup. I hope this helps

[Ben C34]

What the f**k? That plumbing is out of control.

Turbo smart have a good set of images/ instructions on how to plumb an external gate and boost controller.

[Chereboy]

I've looked all over and can't find anything that helps, everything just says to connect the bottom of the wastegate to the Turbo Compressor housing nipple, but my turbo doesn't have one so I needed to splice around with the hosing

[Dose Pipe Sutututu]

Could be your EBC playing silly buggers, at the back of those OG Blitz units is a switch that determines how you've plumbed it and it inverses how the solenoid works.

Also is your stock solenoid still plumbed up? Looks like you've plumbed it up a bit odd. I would just delete the stock solenoid completely.

If you're not running big amounts of boost just skip the t-piece and hook it up as per the following guide:

https://conceptzperformance.com/items/13189/docs/file.pdf

[Chereboy]

I have the rear switch set to Wastegate not Actuator. Not sure if the sudden boost spike from the slit hose damaged the internals of the wastegate. It was working fine prior

[GTSBoy]

On 2/15/2022 at 7:03 AM, Chereboy said:

Not sure if the sudden boost spike from the slit hose damaged the internals of the wastegate.

Wouldn't have. They're not exactly weak things. Even going full travel and hitting the stop at some speed won't hurt them.

It is far more likely that you have a simple plumbing problem.

Take it back to basics, as advised above.

[Chereboy]

Hey guys, I've just presure tested all the hoses with a air Compressor to see if there are any leaks. I'm pushing 5-7psi through all the wastegate and boost hoses I've listed above and there are no leaks. I did notice something I'm not entirely clear of tho. Then I connect the Compressor to the how going into the bottom nipple of the wastegate, the air is easily making its way through the top nipple and the wastegate is not opening at all. Could this be the issue being that all the boost is just somehow bypassing the gate/door maybe through a crack in the internals of the wastegate and coming out the top and therefor not opening the gate? Thanks again guys

[Chereboy]

Here is a video of the wastegate being pressurised with the Compressor

[BK]

On 15/02/2022 at 5:00 PM, Chereboy said:

Hey guys, I've just presure tested all the hoses with a air Compressor to see if there are any leaks. I'm pushing 5-7psi through all the wastegate and boost hoses I've listed above and there are no leaks. I did notice something I'm not entirely clear of tho. Then I connect the Compressor to the how going into the bottom nipple of the wastegate, the air is easily making its way through the top nipple and the wastegate is not opening at all. Could this be the issue being that all the boost is just somehow bypassing the gate/door maybe through a crack in the internals of the wastegate and coming out the top and therefor not opening the gate? Thanks again guys

If that's the case it sounds like a split diaphragm on the gate which will make it not open, because it shouldn't pass air from the bottom to top port and can really only do that if it's split. It would also explain why it was fine and then all of a sudden not. Where is your boost reference for bottom port from again ? - because external gate diaphragms hate vacuum and can damage them, so needs to be pre throttle body always.

Replacing the diaphragm you'll need to know exactly which HKS item it is, but it'll be something like this if you need one:

https://www.rhdjapan.com/hks-standard-wastegate-replacement-parts-diaphragm.html

Time to pull the gate off.

[Chereboy]

The  bottom port is connected to a 3way t peice being (Line from bottom of wastegate, line into powersteering, and another line going to another 3way t peice linking to (throttle body, and top of stock boost solenoid, and then out of the bottom of the stock boost solenoid into the smaller nipple under the top throttle body connection)

[BK]

On 15/02/2022 at 5:51 PM, Chereboy said:

The  bottom port is connected to a 3way t peice being (Line from bottom of wastegate, line into powersteering, and another line going to another 3way t peice linking to (throttle body, and top of stock boost solenoid, and then out of the bottom of the stock boost solenoid into the smaller nipple under the top throttle body connection)

This makes my brain hurt - think you need to simplify this a bit mate. When you say throttle body what do you mean ? Is it before or after the throttle butterfly ? After throttle introduces vacuum - it will kill a wastegate diaphragm done like this.

Anyway if you put air in bottom port of gate and it comes out the top nipple, the wastegate will need a new diaphragm.

[BK]

On 14/02/2022 at 9:12 PM, Ben C34 said:

What the f**k? That plumbing is out of control.

Turbo smart have a good set of images/ instructions on how to plumb an external gate and boost controller.

Yep, I don't really follow the thinking either.

[Chereboy]

[Chereboy]

Damn sorry mate, when I say throttle body I mean intake manifold. Super sorry about any confusion 

Edited February 15, 2022 by Chereboy

[BK]

On 15/02/2022 at 6:09 PM, Chereboy said:

Damn sorry mate, when I say throttle body I mean intake manifold. Super sorry about any confusion 

So your feeding the bottom port of your gate boost and vacuum - no good. Good feed for boost gauge or bov, not wastegates / actuators as it pulls the diaphragm the wrong way for what they were designed. Intake plenum can be used on RB26 as it is before the throttle bodies.

Go and pull your gate off.

[Chereboy]

So wastegates 100% done for ayye?

[BK]

On 15/02/2022 at 6:21 PM, Chereboy said:

So wastegates 100% done for ayye?

Sounds like it, but test off car to confirm. Still cheaper to get a diaphragm for $150 and replace it than get a new gate  Japanese external gates are expensive, but made well - prefer them over the Turbosmart designs.

Shame you don't have a Trust gate as I have a spare good diaphragm here I replaced just because it was 15+ years old when I changed the spring.

[Chereboy]

By test off car, you mean just see the condition of the internals correct? Or run some form of pressure test?

Edited February 15, 2022 by Chereboy