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BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > N20, N26, B46, B48 Turbo Engine / Drivetrain / Exhaust Modifications > Possible to have cold starts with closed wastegate instead of open?
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      11-16-2019, 05:39 PM   #1
Zabiz
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Possible to have cold starts with closed wastegate instead of open?

My mom has a 2014 gl550 with the 4.7 L twin turbo v-8 and when it goes through its cold start you can hear the turbos spool which I am assuming means that the wastegates are closed (pneumatic)

now is that possible to get a turbo spool when we start up our cars (close EWG)
I have catless downpipes and a custom axleback so I can hear it when in sport + but cold start turbo spool would be nice

(if you listen closely you can hear the distinct turbo spool)
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      11-19-2019, 02:12 PM   #2
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I dont think that has anything to do with the wastegate. I don't see why the waste gate would open before reaching target boost.
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      11-19-2019, 09:23 PM   #3
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Quote:
Originally Posted by CandyRedRC46 View Post
I dont think that has anything to do with the wastegate. I don't see why the waste gate would open before reaching target boost.
To heat up the cats. Stock tune opens the WG on cold start for emissions compliance
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      11-20-2019, 08:30 AM   #4
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interesting. well that would be a cool feature to have.
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      11-20-2019, 12:35 PM   #5
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Originally Posted by CandyRedRC46 View Post
interesting. well that would be a cool feature to have.
right!! Hear that turbo spool on cold start, I have bootmod3 so I might ask them if they have any plans on doing something like that
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      11-21-2019, 02:56 AM   #6
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BM3 should have a provision for a “cold start delete” if I recall. That may keep the waste gate shut, or it may not. Worth a shot if you are catless. Otherwise there may be slight risk of damage to your cat. Not sure how much open WG matters, but it definitely has a purpose.
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      11-23-2019, 11:28 AM   #7
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Originally Posted by ProjektAutoScott View Post
BM3 should have a provision for a “cold start delete” if I recall. That may keep the waste gate shut, or it may not. Worth a shot if you are catless. Otherwise there may be slight risk of damage to your cat. Not sure how much open WG matters, but it definitely has a purpose.
The cold start delete only lowers the rpm on startup so the car just starts right to idle speed. Doesn't do anything with the waste gates.
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      11-25-2019, 09:53 AM   #8
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The cold start delete only lowers the rpm on startup so the car just starts right to idle speed. Doesn't do anything with the waste gates.
It does a little more than just idle RPM. The factory cold start setting actually retards the ignition timing a lot, to put an artificial load on the engine to raise EGTs enough to heat the cat up quickly. The timing is pulled so far back that a lot of combustion is occurring outside of the engine (to heat the cat up), hence why cold start is so obnoxiously loud. It is probably doing some adjusting to the vanos and valvetronic as well.
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      11-26-2019, 02:36 AM   #9
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Quote:
Originally Posted by CandyRedRC46 View Post
It does a little more than just idle RPM. The factory cold start setting actually retards the ignition timing a lot, to put an artificial load on the engine to raise EGTs enough to heat the cat up quickly. The timing is pulled so far back that a lot of combustion is occurring outside of the engine (to heat the cat up), hence why cold start is so obnoxiously loud. It is probably doing some adjusting to the vanos and valvetronic as well.
Did not know that. Thanks for making me a bit smarter

However, in the context of the waste gates opening or closing, the BM3 cold start delete is still irrelevant.
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      12-05-2019, 09:56 AM   #10
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Quote:
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Originally Posted by rjdnyy224 View Post
The cold start delete only lowers the rpm on startup so the car just starts right to idle speed. Doesn't do anything with the waste gates.
It does a little more than just idle RPM. The factory cold start setting actually retards the ignition timing a lot, to put an artificial load on the engine to raise EGTs enough to heat the cat up quickly. The timing is pulled so far back that a lot of combustion is occurring outside of the engine (to heat the cat up), hence why cold start is so obnoxiously loud. It is probably doing some adjusting to the vanos and valvetronic as well.
That is so cool hahaah, thank you for that info! I'm just guessing that bmw uses a different cold start route compared to the Mercedes to heat up the cats, also the benz is twin turbo so I'm not sure, also could be that the injectors are too loud to hear any spool
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