Strange exhaust note change...

hotrod182 · 12-09-2007, 02:53 PM

I sometimes start my car and let it idle for a while so that I can let it warm up. I have noticed on many occassions after about a minute or so, all of a sudden the exhaust note changes. I haven't physically verified it yet, but I am willing to bet that the valve on the muffler is opening up. I'm not that worried about it, as I kind of like the deeper exhaust growl my car has at lower speeds, But has anyone else experienced this? Its kind of like it somehow loses vacuum at the actuator a minute after starting the car.

5soko · 12-09-2007, 02:59 PM

the valve on the left(drivers side) closes upion a clod start. it open once the cats have heated up and the engine idle has settled.
the valve again re-opens are specific rpm to lower exhaust note noise during low rpm operation.
if this is what u are talking about.

Terry335 · 12-09-2007, 03:00 PM

It's the valve timing changing, I think.

jcarlucci1 · 12-09-2007, 03:07 PM

Yeah, there's a valve in the left tailpipe that opens once car warms up a bit..this is what people are referring to by "golf tee mod" which permanently opens that valve for a bit more volume from the exhaust.

hotrod182 · 12-09-2007, 03:45 PM

I'm trying to figure out why I would need a golf tee mod if it is already opening up by itself. I figured it would open up only on high load/throttle situations, not when idling. And if it opens when cats heat up, then it opens even more under throttle? Or closes then opens again?

Terry335 · 12-09-2007, 03:47 PM

Quote:

Originally Posted by hotrod182

I'm trying to figure out why I would need a golf tee mod if it is already opening up by itself. I figured it would open up only on high load/throttle situations, not when idling. And if it opens when cats heat up, then it opens even more under throttle? Or closes then opens again?

I think the pitch change is from the engine cam timing changing... but the valve in the tailpipe opens at WOT and sometimes during startup. The golftee mod just makes the car louder for part throttle cruise.

5soko · 12-09-2007, 03:59 PM

Quote:

Originally Posted by hotrod182

I'm trying to figure out why I would need a golf tee mod if it is already opening up by itself. I figured it would open up only on high load/throttle situations, not when idling. And if it opens when cats heat up, then it opens even more under throttle? Or closes then opens again?

yes that is whats happen, like say u start off in first gear, once u pass a certain rpm it closes..
but lets say u start to go WOT it opens all the way. its wierd. but it keep the noise down while just driving aorund. golf tee mod will make it a bit louder around town. not that much louder tho.

ChaneRZ · 12-09-2007, 04:14 PM

i did mine and like it.

jcarlucci1 · 12-09-2007, 04:14 PM

Quote:

Originally Posted by hotrod182

I'm trying to figure out why I would need a golf tee mod if it is already opening up by itself. I figured it would open up only on high load/throttle situations, not when idling. And if it opens when cats heat up, then it opens even more under throttle? Or closes then opens again?

The mod keeps it open all the time...

hotrod182 · 12-09-2007, 04:33 PM

Okay, I just went outside to take a closer look. Before I start my car, the valve is open on the left muffler. After I start the car, the valve closes (you don't feel any exhaust pulsation). But after about a minute of idling ,the valve opens again, you can feel the exhaust on your hand, and the exhaust note deepens. Normal??

jcarlucci1 · 12-09-2007, 04:53 PM

perfectly normal..all that mod does is open it for those first few minutes in which it would normally be closed..

O-cha · 12-09-2007, 04:55 PM

Quote:

Originally Posted by 5sokol335icoupe

the valve on the left(drivers side) closes upion a clod start. it open once the cats have heated up and the engine idle has settled.
the valve again re-opens are specific rpm to lower exhaust note noise during low rpm operation.
if this is what u are talking about.

It's not only that, that valve closes because the engine loads more or something during a cold start. After you do the golf tea thing you will see why as the car will be rather loud during a cold start.

benyl · 12-09-2007, 05:03 PM

Quote:

Originally Posted by O-cha

It's not only that, that valve closes because the engine loads more or something during a cold start. After you do the golf tea thing you will see why as the car will be rather loud during a cold start.

The valve is there just for sound. When you start the car, it goes into a higher idle to "warm up" quicker. At that rpm, the car must be louder and the reason why the valve closes.

I have an e46 330 Ci ZHP (m performance). It does not have the valve like the regular 330 cars do. My car is "always" louder and there is a faint drone at cruising speeds, but not enough to be annoying. The regular 330 is quiet at all speeds with moderate throttle.

If I am not mistaken, the 335 is the same. I will find out soon enough as mine should be here in a week or two.

O-cha · 12-09-2007, 05:05 PM

Quote:

Originally Posted by benyl

The valve is there just for sound.

I thought when I said "after you do the golf tea thing you will see why" kind of indicated that. You do realize that engine load is related to exhaust note right?

Quote:

Originally Posted by benyl

When you start the car, it goes into a higher idle to "warm up" quicker. At that rpm, the car must be louder and the reason why the valve closes.

It's not only that, the car is hardly loud at 1500RPMs after its warmed up. Its only during cold start that its loud.

BoostedBMW · 12-09-2007, 05:36 PM

Quote:

Originally Posted by 5sokol335icoupe

yes that is whats happen, like say u start off in first gear, once u pass a certain rpm it closes..
but lets say u start to go WOT it opens all the way. its wierd. but it keep the noise down while just driving aorund. golf tee mod will make it a bit louder around town. not that much louder tho.

The valve isn't RPM based as far as I know... its based off of engine load. When you are in vac, its closed, and when you are on boost its open. Its just there to make the car quiet while you are cruising on the highway or just driving easy.

ChaneRZ · 12-09-2007, 08:56 PM

it's just for the sound.

turbotko · 12-10-2007, 02:10 PM

It's not the valve as I have the golf tee mod and mine does it too. It starts out pretty loud when started cold then there is a very distinct change in exhaust note after about 30 seconds of idling.

It's normal, don't know what it is, don't really care actually.

benyl · 12-10-2007, 02:25 PM

You said:

Quote:

Originally Posted by O-cha

It's not only that, that valve closes because the engine loads more or something during a cold start.

"Something" suggests to me that you were not sure of your statement.

What is this engine load you speak of? Are you talking about the fast idle when the coolant temperature is below a certain threshold?

Quote:

Originally Posted by O-cha

I thought when I said "after you do the golf tea thing you will see why" kind of indicated that. You do realize that engine load is related to exhaust note right?

Thank you for calling me stupid.

O-cha · 12-10-2007, 02:37 PM

Quote:

Originally Posted by benyl

You said:

"Something" suggests to me that you were not sure of your statement.

What is this engine load you speak of? Are you talking about the fast idle when the coolant temperature is below a certain threshold?

Thank you for calling me stupid.

I'm unsure of exactly how it loads not that it does, that I'm sure of. As it is very clear from the exhaust note.

If you had one you would know, why not wait until you have your car before discussing things about it?

12-09-2007, 02:53 PM	#1
hotrod182 . 1015 Rep 4,029 Posts Drives: 2023 i4 M50 Join Date: Dec 2006 Location: California iTrader: (0)	Strange exhaust note change... I sometimes start my car and let it idle for a while so that I can let it warm up. I have noticed on many occassions after about a minute or so, all of a sudden the exhaust note changes. I haven't physically verified it yet, but I am willing to bet that the valve on the muffler is opening up. I'm not that worried about it, as I kind of like the deeper exhaust growl my car has at lower speeds, But has anyone else experienced this? Its kind of like it somehow loses vacuum at the actuator a minute after starting the car.
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12-09-2007, 02:59 PM	#2
5soko Brigadier General 358 Rep 4,633 Posts Drives: M5 Join Date: Aug 2007 Location: Brooklyn, NY iTrader: (4)	the valve on the left(drivers side) closes upion a clod start. it open once the cats have heated up and the engine idle has settled. the valve again re-opens are specific rpm to lower exhaust note noise during low rpm operation. if this is what u are talking about. __________________ Current: E63S AMG 4matic RENNtech \|\| M5 Evolve..Eventuri \|\| F10 LCI 535i MHD
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12-09-2007, 03:00 PM	#3
Terry335 Banned 106 Rep 2,587 Posts Drives: 335i Join Date: Jan 2007 Location: Socal iTrader: (0)	It's the valve timing changing, I think.
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12-09-2007, 03:07 PM	#4
jcarlucci1 Lieutenant Colonel 72 Rep 1,642 Posts Drives: Jet Black 335i Join Date: Mar 2007 Location: Tampa iTrader: (10)	Yeah, there's a valve in the left tailpipe that opens once car warms up a bit..this is what people are referring to by "golf tee mod" which permanently opens that valve for a bit more volume from the exhaust.
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12-09-2007, 03:45 PM	#5
hotrod182 . 1015 Rep 4,029 Posts Drives: 2023 i4 M50 Join Date: Dec 2006 Location: California iTrader: (0)	I'm trying to figure out why I would need a golf tee mod if it is already opening up by itself. I figured it would open up only on high load/throttle situations, not when idling. And if it opens when cats heat up, then it opens even more under throttle? Or closes then opens again?
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12-09-2007, 04:14 PM	#8
ChaneRZ If You Aint First, You're last !!! 106 Rep 2,508 Posts Drives: 08 BMW 335i, 01 Honda Prelude Join Date: Sep 2007 Location: California iTrader: (0)	i did mine and like it. __________________ 08 BMW BSM 335i 6MT (Sports, Premium, NAV, PDC, AS, IPOD, HD Radio, Rear Sunshade, OEM Alarm) Angel iBright V3, Luminics Fog Bulb, Turbo Tuner, K&N Drop in Filter, Dinan Exhaust, Dinan Pedals, Vorsteiner CF Front Lip, and CF Rear Diffuser. Ordered:08/25/07 Started: 09/09/07 Finished: 09/14/07 On Ship: 09/15/07 Arrived: 10/08/07 Delivered: 10/10/07
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12-09-2007, 04:33 PM	#10
hotrod182 . 1015 Rep 4,029 Posts Drives: 2023 i4 M50 Join Date: Dec 2006 Location: California iTrader: (0)	Okay, I just went outside to take a closer look. Before I start my car, the valve is open on the left muffler. After I start the car, the valve closes (you don't feel any exhaust pulsation). But after about a minute of idling ,the valve opens again, you can feel the exhaust on your hand, and the exhaust note deepens. Normal??
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12-09-2007, 04:53 PM	#11
jcarlucci1 Lieutenant Colonel 72 Rep 1,642 Posts Drives: Jet Black 335i Join Date: Mar 2007 Location: Tampa iTrader: (10)	perfectly normal..all that mod does is open it for those first few minutes in which it would normally be closed..
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12-09-2007, 08:56 PM	#16
ChaneRZ If You Aint First, You're last !!! 106 Rep 2,508 Posts Drives: 08 BMW 335i, 01 Honda Prelude Join Date: Sep 2007 Location: California iTrader: (0)	it's just for the sound. __________________ 08 BMW BSM 335i 6MT (Sports, Premium, NAV, PDC, AS, IPOD, HD Radio, Rear Sunshade, OEM Alarm) Angel iBright V3, Luminics Fog Bulb, Turbo Tuner, K&N Drop in Filter, Dinan Exhaust, Dinan Pedals, Vorsteiner CF Front Lip, and CF Rear Diffuser. Ordered:08/25/07 Started: 09/09/07 Finished: 09/14/07 On Ship: 09/15/07 Arrived: 10/08/07 Delivered: 10/10/07
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12-10-2007, 02:10 PM	#17
turbotko Lieutenant 67 Rep 527 Posts Drives: 09 E90 M3 Join Date: May 2007 Location: georgia iTrader: (3)	It's not the valve as I have the golf tee mod and mine does it too. It starts out pretty loud when started cold then there is a very distinct change in exhaust note after about 30 seconds of idling. It's normal, don't know what it is, don't really care actually. __________________ 10 AW on fox E90 M3 with 2 pedals, gentleman’s ride 08 AW on fox E92 M3 also 2 pedals, a bit more rowdy
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