Wastegate Weirdness

[Chumpaumpalumpa]

Hello all, this one has me stumped. I'm running an internally gated TD06 FP 20G with an HX-35 actuator which I bench tested to open at about 20 psi. I am dumping to atmosphere so it is obvious when the wastegate cracks. At half throttle, it opens at 5-9 psi and seems to crack open at 4k RPM regardless of boost. Just holding or mildly accelerating at 4k will crack it open. I tried both 3 turns (half a hole) and 6 turns tightened with the same results. The Hallman MBC I am using is hooked up correctly and is turned all the way down. Cranking it down all the way keeps the wastegate from opening.

 

[Chumpaumpalumpa]

Anyone?

 

[Dsmkauai]

So are you unable to control boost? Not sure what your asking? Have you tried without the mbc to see what it does?

 

[Justin Lauscher]

I agree with Kauai, get rid of that mbc and do a test run with your wastegate directly ran to your pressure source.

 

[Chumpaumpalumpa]

Ok I'll try that. What doesnt make sense is that its opening below spring pressure and I didnt think that was possible.

 

[Dsmkauai]

to much airflow going into the wastegate area and blowing it open. Sounds like maybe the actuator isn't up to par, even thou it should be. But your right it should hold to 18-20psi before popping. When I had mine on my 16g I could get 18psi with just the acuator and no mbc, was solid. Are you sure the flapper is sealing correctly?

 

[Justin Lauscher]

It's almost like its connected to your exhaust and not your piping

 

[Chumpaumpalumpa]

to much airflow going into the wastegate area and blowing it open. Sounds like maybe the actuator isn't up to par, even thou it should be. But your right it should hold to 18-20psi before popping. When I had mine on my 16g I could get 18psi with just the acuator and no mbc, was solid. Are you sure the flapper is sealing correctly?

Brand new hot side from FP and has a bigger WG port. Still doing the same as the old cracked housing. I'm going to run a line to the wastgate from the boost source and see what happens. The boost source is on the IC pipe right after the turbo (downfiring 20g)

 

[Chumpaumpalumpa]

OK just got back from the wastegate pressure test run. it does the same thing as before. Although I did notice that when it opens at 4k it isnt just cruise i have to see like 2psi and it'll crack open otherwise it opens around 7psi. Checked again that it opens just barely when it sees 20psi on the bench. This is really confusing.

 

[Chumpaumpalumpa]

C'mon guys I know someone out there has an idea of what to try next.

 

[Mauispyder]

I had a similar issue, shimmed the waste-gate, solved the lag. I had the turbo and o2 housing off, I marked the wastegate flapper arm and the casting next to it with a sharpy where it was closed, I added washers until it was on the mark.

You've probably seen this thread already Chump, but maybe you could pm one of these guys to get a little more detail.

 

[sidewaystsi]

I noticed you didnt mention if the car feels like its low on power from lack of boost. Is your boost gauge reading accurately or has the line gotten clogged with something or a hole in it.

 

[Chumpaumpalumpa]

I noticed you didnt mention if the car feels like its low on power from lack of boost. Is your boost gauge reading accurately or has the line gotten clogged with something or a hole in it.

Well I wouldn't know if that's why it's down on power, it's been like this since day one on the only cracked housing. It should be making 350whp but it feels more like the 250- 270whp range. Very inconsistent too. 9/10 pulls are slow feeling, but every once in a while on a cold night it'll pull hard. I feel like that's from the tune though. I have absolutely no boost leaks and the fuel pressure is dead on 37psi. How can I check if the boost gauge is reading right?

Maui I dont think I read too much into that I'll have another look thank you.

 

[sidewaystsi]

Hook the gauge up to whatever your using to bench test the actuator and see it both gauges read the same.

 

[sidewaystsi]

Only other thing i can think of is a clogged exhaust system and the exhaust pressure is high enough to force open the gate.

 

[Chumpaumpalumpa]

Not clogged I checked before install. I'll verify the gauge was reading correctly.

 

[Chumpaumpalumpa]

So I went to test with a German hand tester pump I have and I could only get it up to 12psi because it was leaking through the Wastegate. I think the diaphragm may be torn? That really doesnt make sense because you'd think the opposite would happen from what is happening now.