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G30 (2017 - Current)
The next generation 5 Series, chassis code G30, arrives at dealers in February 2017. Looking like a scaled down 7 Series and riding on the CLAR platform, the new 5 Series will have a focus on lightweight and sporty performance. Engines options will come from BMW's new B family for the 530 and 540 and a turbocharged V8 for the M550i. Read more about the 2017 5 Series

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  #1  
Old 04-03-2020, 12:16 PM
sjb993 sjb993 is offline
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G0 540i exhaust question.

Typo in the title G0 = G30. Why have BMW chosen to have a baffle in one of the tailpipes that opens at a certain RPM?

Thanks.

Last edited by sjb993; 04-03-2020 at 12:18 PM.
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  #2  
Old 04-03-2020, 12:25 PM
Jack_88 Jack_88 is offline
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Originally Posted by sjb993 View Post
Typo in the title G0 = G30. Why have BMW chosen to have a baffle in one of the tailpipes that opens at a certain RPM?

Thanks.
Noise, naturally. It keeps the car quieter when you're just cruising, opening it up when you demand more flow and expect it to be noisier anyway. It probably doesn't do a lot for noise in the cabin and probably doesn't do a lot for performance, but it should make some difference. Manufacturers like BMW are always looking for little ways to make their cars better. Just look at the windshield wipers programmed to alternate their positioning when you unlock the car, so that they don't sit in the same position all the time, reducing uneven wear.
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Old 04-04-2020, 12:36 AM
sjb993 sjb993 is offline
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OK thanks.

I was wondering whether the baffle was used as a way of regulating the exhaust system back pressure.
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  #4  
Old 04-04-2020, 06:33 AM
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Quote:
Originally Posted by sjb993 View Post
Why have BMW chosen to have a baffle in one of the tailpipes that opens at a certain RPM?

Thanks.
Here’s an explanation in regards to the exhaust flap (baffle?) from the TIS that goes along with what Jack_88 wrote in his reply. Click the link above the pic below:

https://www.newtis.info/tisv2/a/en/g...lap-2/Im2GgsKi



1. Electrical exhaust flap
2. 4-pin plug connection


Example: integrated exhaust flap in the rear silencers



1. Electrical exhaust flap
2. 5-pin plug connection

The exhaust flap is unable to move to an intermediate setting. The exhaust flap is either fully opened or fully closed. The preferred position when detecting faults or upon failure of the actuation as well as after having stopped the engine is the closed position. In vehicles with M Sport exhaust system the exhaust flap is opened in sports mode.
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97 740iL (Arctic Silver) <<~>> 99 540iT (Orient Blue) <<~>> 95 525IT (Alpine White)
91 735iL (Schwarz Black) <<~>> 85 325e (Bronzit)

https://www.bimmerforums.com/forum/attachment.php?attachmentid=637911&d=1538398374&thumb=1&stc=1

Last edited by QSilver7; 04-04-2020 at 06:41 AM.
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Old 04-04-2020, 07:06 AM
sjb993 sjb993 is offline
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Thank you for the replies.
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Old 04-04-2020, 08:25 AM
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Warp Ten Warp Ten is offline
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I don't think all the info above is correct. I have a 2019 540xi M Sport. The exhaust flap is not open in the Sport mode at start up or when idling. It may open sooner in Sport mode under heavy throttle but I can't tell. It is always closed on startup to help the catalytic converter heat up. As some folks do, I removed the connecting clip and wired it open and there was no difference in sound that I could hear at idle or on the road. Finally switched to a louder M Sport exhaust with no flap valve. --Bob
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Old 04-05-2020, 10:26 AM
jjsC6 jjsC6 is offline
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Originally Posted by Warp Ten View Post
I don't think all the info above is correct. I have a 2019 540xi M Sport. The exhaust flap is not open in the Sport mode at start up or when idling. It may open sooner in Sport mode under heavy throttle but I can't tell. It is always closed on startup to help the catalytic converter heat up. As some folks do, I removed the connecting clip and wired it open and there was no difference in sound that I could hear at idle or on the road. Finally switched to a louder M Sport exhaust with no flap valve. --Bob
Unless you have coded it, the car does not start in sport mode.
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Old 04-05-2020, 01:33 PM
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Originally Posted by jjsC6 View Post
Unless you have coded it, the car does not start in sport mode.
I have it coded to start in Sport mode.--Bob
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Old 04-05-2020, 02:10 PM
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Originally Posted by Warp Ten View Post
I don't think all the info above is correct. I have a 2019 540xi M Sport. The exhaust flap is not open in the Sport mode at start up or when idling. ... --Bob
I clicked the link in my post above to read the functional description again...because I don't see where it says what is bolded in your quote above.

The functional description (at the link to the TIS) mentions that the flap operates by way of a PWM signal based on variables...and it listed 3:
  1. Engine speed
  2. Driving speed
  3. Load

For some reason I'm not seeing anything that says the flap opens when in sport mode, start up or when idling. It does say that if it faults...it does so in the open position. At start up and when idling...the 3 variables that would cause the DME to send a PWM signal to open the flaps is low or not existent...so the flaps should be closed to reduce noise at start up and when idling (not open). Or I'm I not reading/interpreting the TIS correctly?
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Q {BMW CCA Member #191509}
2006 E53 X5 4.4i (Sterling Gray) 12/05 mfg date <<~>> 2013 F06 650ix Gran Coupe` (Black Sapphire) 1/13 mfg date
(SOLD)
97 740iL (Arctic Silver) <<~>> 99 540iT (Orient Blue) <<~>> 95 525IT (Alpine White)
91 735iL (Schwarz Black) <<~>> 85 325e (Bronzit)

https://www.bimmerforums.com/forum/attachment.php?attachmentid=637911&d=1538398374&thumb=1&stc=1

Last edited by QSilver7; 04-05-2020 at 02:25 PM.
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  #10  
Old 04-06-2020, 07:19 AM
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Quote:
Originally Posted by QSilver7 View Post
I clicked the link in my post above to read the functional description again...because I don't see where it says what is bolded in your quote above.

The functional description (at the link to the TIS) mentions that the flap operates by way of a PWM signal based on variables...and it listed 3:
  1. Engine speed
  2. Driving speed
  3. Load

For some reason I'm not seeing anything that says the flap opens when in sport mode, start up or when idling. It does say that if it faults...it does so in the open position. At start up and when idling...the 3 variables that would cause the DME to send a PWM signal to open the flaps is low or not existent...so the flaps should be closed to reduce noise at start up and when idling (not open). Or I'm I not reading/interpreting the TIS correctly?

Last summer I was behind a 3 series which I could see had an exhaust flap like mine. At the stop light it was closed. Intrigued, I watched it as the car accelerated away. The flap opened under moderate acceleration. Had never actually seen that before. Got too far apart when up to speed to see if it closed again when throttle was reduced. --Bob
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