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Been working on a DIY turbo setup for some time:
-Flipped and chopped/v-banded C6 manifolds hotside
-on3 76mm 1.0ar turbo in battery position
-tial 38mm wastegate
-tial 50mm bov
-FMIC
-open downpipe under engine bay for now during initial setup, approx 4 feet off the turbo 3"
No apparently leaks on the hot side but I cannot seem to get the turbo to spool or build boost.
It spins freely. Boost gauge gets to 0 pretty quickly but won't go above it. Running second weakest spring in the wastegate, maybe it's pushing it open early or something? I physically cannot hear the turbo spool other than the tiniest amount. I don't think its a cold side leak because I can't hear the turbo spool.
Anyway, looking for some troubleshooting steps here. Thanks all.
Last edited by ledesordre; Aug 1, 2018 at 09:21 AM.
BOV open? Even the slightest amount? Stuff a paper trowel or rag in the port and see if it blows out while your driving. You could also try pulling the line off the BOTTOM of the gate. That’d ensure it’s only opening due to backpressure.
BOV open? Even the slightest amount? Stuff a paper trowel or rag in the port and see if it blows out while your driving.
Thought about that, but wouldn't I still hear the turbo spool if the leak was on the cold side? I've driven turbo cars before, I don't hear any spool at all.
Your pics are confusing. I see the BOV in one pic that looks to be on a hot side pipe, then I see it on a cold pipe in the car near the intercooler.
Ah, dont look too closely, those were just some loose pictures I found from when I was fabricating the setup. I definitely have the BOV on the cold side between the turbo and the intercooler. Will try running it with out a wg line.
Ah, dont look too closely, those were just some loose pictures I found from when I was fabricating the setup. I definitely have the BOV on the cold side between the turbo and the intercooler. Will try running it with out a wg line.
No lines to the gate will definitely tell us something.
is their a boost reference to the BOV and spring to hold it shut?
you'll still hear spool with it open.
do you have your tune also?
no valve seat on the gate will do the same thing as will no springs in the gate
Running BOV boost source off the intake manifold
Running the Wg boost source off the turbo compressor housing source (still never hear it spool)
Still running a stock tune until I can get kinks worked out
Valve seat is present, afaik, there is the 2nd weakest spring in the wastegate presently. I changed springs a while ago, the spring has to sit on the valve seat right?
Will try to run wg without reference line and see what happens after work, still gathering ideas and I appreciate it you guys, thx.
if you have the fabrication tooling and skills you could make up a blanked pipe with a fitting in it that you can put where your air filter is and clamp to the compressor housings.
use a regulator and compressed air to put air into the comp housing and listen for where it goes. it will show you if your BOV is leaking, if the gate is leaking or if cooler/pipework is leaking.
some air will flow through the engine and past the open valves but if you negate that and focus on identifying and leaks it may help.
76mm should spool fine on your combo. provided the tune isn't hindering you
What do you mean the spring should sit on the valve? There should be a small plate with a rubber diaphragm or O-rings hooked to it inside the wastegate. That’s what the spring Sits on. You should have to crush the spring down to get the wastegate dome back once you have it opened up.
Running the Wg boost source off the turbo compressor housing source (still never hear it spool)
Still running a stock tune until I can get kinks worked out
Valve seat is present, afaik, there is the 2nd weakest spring in the wastegate presently. I changed springs a while ago, the spring has to sit on the valve seat right?
Will try to run wg without reference line and see what happens after work, still gathering ideas and I appreciate it you guys, thx.
no the spring does not sit on the valve seat. It sits atop the aluminum piston with the diaphragm. The top presses down on it. If you have it on the valve seat then that’s keeping the valve open and not closed. The valve is normally closed.
no the spring does not sit on the valve seat. It sits atop the aluminum piston with the diaphragm. The top presses down on it. If you have it on the valve seat then that’s keeping the valve open and not closed. The valve is normally closed.
Thank you, “piston” is the word I was looking for. I was at a stoplight typing and couldn’t think of it!!! Haha
I had my car together one year after big change, but I never opened up the motor. Well, long story short, I had oil pressure but it never got over 30psi. Rev it, drive, change to 50W oil...30 PSI. Put a new oil pump in it, still 30 PSI.
Guess what? THE GAUGE WAS BAD! A small piece of junk fell into the gauge through the hole that the little 12V light goes to illuminate the gauge.
In closing, never trust the gauge 100%. So, do 1 of 2 things: Either get an air hose and try to BLOW air into it, say 10 PSI? Or borrow another gauge from someone?
Are you hooked up to the ECM? What is the MAP pressure actually saying as well?
On my lunch break just now I got on it and made about 0-1 PSI on the gauge and let off, basically had to floor it to make it do that. It had a weak *** BOV sound after that. Could barely here the turbo start to spool.
I tried it with the wastegate vac port open as suggested earlier in the post. Did not make a difference.
Thanks for the responses. I did have to clamp the wastegate shut to put it back together with the new spring. It seems like everything is in tact in there, there was a good bit of tension on it trying to keep the wastegate case apart before I clamped it down. I will find a blow up diagram and inspect it again later. It was a used wastegate so it could be an issue.
I don't believe the boost gauge is bad, I'm on my second boost gauge just in case. I believe it is not building boost.
Trying to find a blow up diagram of the Tial MVS 38mm, going to take mine apart after work regardless.
just put compressed air into signal port using a regulator and slowly wind it up. you'll soon see if the spring or seat is no good. or if the diaphragm is torn. saves you removing and stripping it if there's nothing wrong.
you definitely cant hear any exhaust gas out the screamer pipe at idle?
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Not building boost 
