Theoretical wastegate actuator adjustment question

pjr710 · 05-12-2019, 09:37 PM

Ok so I have my front and rear turbo "closing" at 6hg according to my harborfreight vacuum gun. I use a mechanics stethoscope, then vacuum the line directly to the turbo and wait to hear a "ping" .. I can hear the wastegate creep close > then ping > then no more sound which leads me to believe it's closed.

My problem is that my throttle response is slightly laggy as is my boost build up. I've pressure tested for leaks, vac lines are good, vanos is new, boost solenoids are new.

So I'm hypothesizing here and wondering .... If i adjust my front and rear actuators to close at lets say 4hg ... would that possibly in anyway help me spool up faster?

At first I thought no, but then I was thinking it might. The way I understand the computer is that the car just tells the wastegates to "close" or "open" with the WGDC ... my car goes to 100% for a little bit then drops off, so my theory is that if my car expects the WGs to close at 6HG then maybe it's finessing that closure at exact precision, whereas if I had it close at 4HG maybe I would surprise the car then it would have to back off the WGDC almost instantly.

I dunno I might try it for myself and see, what I would do is put two washers on my front turbo, see what that closes at in HG, then match my rear to the same.

If this sounds insane then lmk, but I'm happy to hear others thoughts.

studio54 · 05-13-2019, 02:17 AM

I recently adjusted my wastegate on new Mitsubishis OEM turbos.

I based my adjustement with a value that we find on forum that is 5.9inHG to close, and moderate resistance to move the disc.

All i can say is that there is a decent range in inHG between the closed position with moderate resistance, and the closed position with loosen flapper. As you cannot touch the disc with the stethoscope method, maybe your discs are still loosen at 6inHG, even if you hear a "ping" ?? but i am not an expert.

You can try maybe inHG by inHG, like now you are at 6inHG, try at 5inHG.

If you go too far, you can get overboost problem.

05-13-2019, 12:33 PM

I was hoping this would easily be solved by replacing the boost solenoids, but it sounds like those can be ruled out.

Post a log OP...results would certainly be interesting.

pjr710 · 05-13-2019, 01:17 PM

Quote:

Originally Posted by FCobra94

I was hoping this would easily be solved by replacing the boost solenoids, but it sounds like those can be ruled out.

Post a log OP...results would certainly be interesting.

Torgus · 05-13-2019, 09:23 PM

Just because the waste gates seat does not mean it is seating completely closed. Or not closed correctly every time.

pjr710 · 05-15-2019, 10:43 AM

Quote:

Originally Posted by Torgus

Just because the waste gates seat does not mean it is seating completely closed. Or not closed correctly every time.

Soooooo do u think if i made it close at 5 or 4hg it would make a difference?

Also my turbos do act a little weird. It seems like if i gradually step on the pedal the turbos build boost correctly. It seems only when going “WOT” they lag.

Torgus · 05-15-2019, 11:32 AM

Quote:

Originally Posted by pjr710

Soooooo do u think if i made it close at 5 or 4hg it would make a difference?

Also my turbos do act a little weird. It seems like if i gradually step on the pedal the turbos build boost correctly. It seems only when going “WOT” they lag.

I would hazard to guess that the WG seats better when it is slowly closed vs. a quick shut it may not close fully close correctly. I could be wrong.

Stupid waste gate design selection by BMW.

I would not suggest making it close at a different hg but I also am no turbo expert. I just know stock snails can go suck a big one.

pjr710 · 05-15-2019, 03:05 PM

Quote:

Originally Posted by Torgus

I would hazard to guess that the WG seats better when it is slowly closed vs. a quick shut it may not close fully close correctly. I could be wrong.

Stupid waste gate design selection by BMW.

I would not suggest making it close at a different hg but I also am no turbo expert. I just know stock snails can go suck a big one.

Amen!

05-12-2019, 09:37 PM	#1
pjr710 Lieutenant 115 Rep 541 Posts Drives: 335i Join Date: Sep 2015 Location: PA iTrader: (0)	Theoretical wastegate actuator adjustment question Ok so I have my front and rear turbo "closing" at 6hg according to my harborfreight vacuum gun. I use a mechanics stethoscope, then vacuum the line directly to the turbo and wait to hear a "ping" .. I can hear the wastegate creep close > then ping > then no more sound which leads me to believe it's closed. My problem is that my throttle response is slightly laggy as is my boost build up. I've pressure tested for leaks, vac lines are good, vanos is new, boost solenoids are new. So I'm hypothesizing here and wondering .... If i adjust my front and rear actuators to close at lets say 4hg ... would that possibly in anyway help me spool up faster? At first I thought no, but then I was thinking it might. The way I understand the computer is that the car just tells the wastegates to "close" or "open" with the WGDC ... my car goes to 100% for a little bit then drops off, so my theory is that if my car expects the WGs to close at 6HG then maybe it's finessing that closure at exact precision, whereas if I had it close at 4HG maybe I would surprise the car then it would have to back off the WGDC almost instantly. I dunno I might try it for myself and see, what I would do is put two washers on my front turbo, see what that closes at in HG, then match my rear to the same. If this sounds insane then lmk, but I'm happy to hear others thoughts.
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05-13-2019, 02:17 AM	#2
studio54 Captain 206 Rep 714 Posts Drives: n54 Join Date: Feb 2017 Location: belgium iTrader: (0)	I recently adjusted my wastegate on new Mitsubishis OEM turbos. I based my adjustement with a value that we find on forum that is 5.9inHG to close, and moderate resistance to move the disc. All i can say is that there is a decent range in inHG between the closed position with moderate resistance, and the closed position with loosen flapper. As you cannot touch the disc with the stethoscope method, maybe your discs are still loosen at 6inHG, even if you hear a "ping" ?? but i am not an expert. You can try maybe inHG by inHG, like now you are at 6inHG, try at 5inHG. If you go too far, you can get overboost problem.
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05-13-2019, 12:33 PM	#3
FCobra94 Guest 0 Rep n/a Posts Drives:	I was hoping this would easily be solved by replacing the boost solenoids, but it sounds like those can be ruled out. Post a log OP...results would certainly be interesting.
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05-13-2019, 09:23 PM	#5
Torgus Slow. 3808 Rep 7,150 Posts Drives: N54 6466 100% E85 + Meth Join Date: Jun 2012 Location: Boston, MA iTrader: (2) Garage List 2007 BMW E92 [10.00] 2007 BMW E90 [0.00] 2006 BMW E91 [0.00]	Just because the waste gates seat does not mean it is seating completely closed. Or not closed correctly every time.
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