DIY: Golf tee mod / exhaust flapper disable w/ pictures

[jeremyc74]

Originally Posted by GtiGyver

May cause issues with the brake booster.
Basically why play with fire?

I'd plug the line, but the brake assist isn't really a concern. The way they're tapped in on modern cars is designed to prevent a vacuum leak from effecting braking performance.

If I were going to do this mod, I'd just unplug the connector at the solenoid in the trunk and leave the vacuum line hooked up.

[ianc]

This mod is known to have reduced driving mileage and the lack of back pressure with the pipes fully open loses a tad of torque down low. I did it on my 335i and that was exactly the case. Mileage got horrible

Anyone noticed any definite deterioration in mileage after doing this mod? Seems unlikely, but...

ianc

[jeremyc74]

Originally Posted by ianc

Anyone noticed any definite deterioration in mileage after doing this mod? Seems unlikely, but...

ianc

I don't see any way that's possible honestly. The A/F ratio is controlled, and this isn't going to alter it. Also, if it were true, people running aftermarket exhaust would have the same problem, and I haven't seen where that's the case at all.

Someone's going to have to explain the dynamics behind backpressure helping fuel economy before I buy into it personally.

[tgxmike]

So I have not read all 8 pages to this post, But I have done this mod for ~12weeks and then removed it again. So here goes.

128i non-sport

Performance remained the same as far as I could tell from seat of the pants. I don't have access to a dyno, and didn't car to try a stop watch.

Milage, well it went from 23mi/gal to 21.5mi/gal and then has not gone back up after removing the mod. I bought a house during that time and went from 12mi highway and 5 mi backroad to a complete back road drive to work, so I would imagine the commute change is the ONLY contributor to milage. One long trips on the highway that I have tracked, still getting ~27-28mi/gal. So I don't think the mod had an effect on fuel economy.

The noise. was it louder, yes def, but I also have hypersensitive hearing. so I notice a lot more than most people. It was really only different when I would Sidestep/heel-toe the throttle when in low rpm (<3K rpm) around town driving. which makes sense since this is probably what the silencer is used for.... noise polution in cities.

During the mod, I got a check engine light. dealer says it is a gas tank vent valve that has to be replaced. Could it be the mod.... maybe?? will I ask my dealer to confirm, FUCK NO!

After my service will I put the mod back on? No!

Just my experience

[tgxmike]

Originally Posted by chrisb321

So after my wife having this car since December I decided to have a go at the golf tee mod. I thought the exhaust already sounded throaty and I was interested to see what difference this made.

Now I see why it sounded so deep, the hose was already disconnected, just lying there without any golf tee or plug. I added a golf tee and tucked it away.

Does anyone know of the knock on effect of not plugging the hose?

The reason I ask is I have been having a problem where upon releasing the brake after a long stop (at a light), instead of the car rolling forward it was as if the brakes were still on for a second or two then suddenly they release and the car does a little jump forward (this is an automatic). It happens randomly about 5 times a day but sometimes not at all.

I was taking it in for this to be checked in a few weeks. If this fixes it I will be so happy.

Could this be related?

the brake "sticking" sounds like the hill hold feature, but I have not heard of that being integrated into the Auto. Interesting. I did just take my mod off recently, I will see if this sticking like feeling will go away.

[ianc]

I'll try this mod for grins, and from boredom, because after my suspension project, I don't have anything car-related to do just now.

My interpretation (suspicion) of the valve's function assumes that one pipe is quieter than two. Also, that the second pipe is spring loaded to stay open.

Engine off, 0 vacuum; 2nd pipe is open.
Start engine, high vacuum at idle & low RPM's pulls valve closed; sound is quieter.
Running at larger throttle openings causes lower vacuum> just above atmospheric > 2nd pipe opens.

Subject, of course, to the mad desires of the ECU...

Is this inconsistent with the way the valve behaves? Too lazy to check, but I'm using BB's anyway...

ianc

[Sylon]

I just did this on my N55 (via ziptie method), and the difference is VERY significant. Not annoying, but wow this thing sounds so much meaner. I think this is how the 135i should sound. I think its a good competitor in sound to that of the M3.


EDIT: I need to charge my camera battery, but I'll get you guys some video sometime this weekend.

[1addiction]

did this mod
love it
reminds me of the rumble you get in your ear drum from a jetski

[pimmy]

I wanted to mod my car (125i) but i heard no difference.
All I could find, was that the flap doesn't close at all! No time. (There is no suction on the tube).
Tried everything, but l can't close it (Or is it standard with the M-package)

Anyone had this too?

But i wanted to know how it would sound with one flap closed. Fixed it in the closed position, and i could defentely hear the difference! Much better when it's open!

[ianc]

I did it also and didn't detect any change. I undid it last nite. Same...

ianc

[premedsoccergod]

just did the mod and i closed off the hose (black with yellow line) but i didn't close off the black thing that it was originally attached to. it's ok right?
anyways i noticed a major difference. very cool free mod

[sb335is]

Originally Posted by premedsoccergod

just did the mod and i closed off the hose (black with yellow line) but i didn't close off the black thing that it was originally attached to. it's ok right?
anyways i noticed a major difference. very cool free mod

same. but im not sure if this contributes but i feel like after a wash the rear of my car is filthy dirty after only a few miles... and im thinking that it might be partially the cause

[MrBimmer]

is it possible to undo this mod if you dont like the result?

[Sylon]

Originally Posted by MrBimmer

is it possible to undo this mod if you dont like the result?

Yes. Its completely reversable.

[N55_NOLE]

Thanks for this DIY. It was so simple I did it in the parking lot of advanced auto parts! Definitely sounds much better!

[Greenkirby21]

Hey guys, I took a pic of my 128i. There weren't a lot of pics. Mod literally took me 1 min! I found it easiest to go near the bottom left tire. Exhaust is louder : ). I made it snug, but not so tight because I don't want to break the hose!

I hope i did this right xD

[bradleyland]

For those wondering what this does, the mod causes the flap to open all the time. Normally, it's closed on cold start. Once you pinch the tube, you'll find that the exhaust comes out both sides, even when the car is idle.

[bradleyland]

I'm amazed that anyone couldn't tell the difference with this mod. I ended up reverting to factory config because there was an audible drone at around 45 MPH with the cruise on. The nice thing about this mod is that you can switch it back and forth. I might do it again this fall when I'm driving around with the windows down more often.

[The1]

Sorry to bring this back from the dead.

I disengaged my valve using the solenoid in the trunk method. 2 reasons. easy to put back together, and i didn't have to lay down, as i'm 6'4 almost 6'5, it's a long way down to stick my head under the car.

I will stick my BT tool on the car in a day or two to see if it actually throws a code or not.

This DOES make an audible difference in the low end of the rev band, It reminds me of my buddies 98 M3 for sound volume in city driving. However, there is a bit of a drone on the highway, but it's nothing conversation and music wont cover up.

As for back pressure comments from people. no matter what exhaust is on a car, it's causing mroe back pressure then the turbos want. the best exhaust for a turbo motor is a megaphone shaped pipe about 18" long.

as for the N/A cars, i can't say without talking to any of the techs, but, the valve may actually be used to improve fuel mileage and emissions, as backpressure is actually needed on a N/A motor so that valve may be working in conjunction with the vanos system or whatever it is in BMW. that being said. you probably won't notice anything, only a little more noise. (if i'm correct.)


This mod in my opinion was worth it to hear my car clear it's throat. That being said, it's probably more noticable in my car as i have an intake.

question for anyone out there, when you hit about 3500 rpm on medium throttle, do you hear a satisfying moan from the exhaust? well, that's due to the valve opening, if you do this mod, that sound starts a lot sooner, but much lower pitched.

[bradleyland]

Originally Posted by The1

I will stick my BT tool on the car in a day or two to see if it actually throws a code or not.

I'm really curious to see whether it throws a code. I clipped the zip tie off mine after a couple of days. Too much drone for around town. It was interfering with my concentration while I was trying to text and drive. Wouldn't want to be unsafe.

[1013mm]

it doesnt throw a code for me.

[Sylon]

Originally Posted by The1

Sorry to bring this back from the dead.

I disengaged my valve using the solenoid in the trunk method. 2 reasons. easy to put back together, and i didn't have to lay down, as i'm 6'4 almost 6'5, it's a long way down to stick my head under the car.

I will stick my BT tool on the car in a day or two to see if it actually throws a code or not.

This DOES make an audible difference in the low end of the rev band, It reminds me of my buddies 98 M3 for sound volume in city driving. However, there is a bit of a drone on the highway, but it's nothing conversation and music wont cover up.

As for back pressure comments from people. no matter what exhaust is on a car, it's causing mroe back pressure then the turbos want. the best exhaust for a turbo motor is a megaphone shaped pipe about 18" long.

as for the N/A cars, i can't say without talking to any of the techs, but, the valve may actually be used to improve fuel mileage and emissions, as backpressure is actually needed on a N/A motor so that valve may be working in conjunction with the vanos system or whatever it is in BMW. that being said. you probably won't notice anything, only a little more noise. (if i'm correct.)


This mod in my opinion was worth it to hear my car clear it's throat. That being said, it's probably more noticable in my car as i have an intake.

question for anyone out there, when you hit about 3500 rpm on medium throttle, do you hear a satisfying moan from the exhaust? well, that's due to the valve opening, if you do this mod, that sound starts a lot sooner, but much lower pitched.

I lol'd at the first part, as I am also 6ft4 and you sir are just lazy, lol, jk



Anyways, question for you. First, do you have an N54 or N55? secondly, (and this part is for everyone), have any of you noticed the cool sound the 135i makes when you are in second gear, coasting at around 20-25mph, and you barely tap the throttle. And i mean tap, like not even enough to accelerate. Sometimes you dont even have to tap the throttle to hear it, it'll sometimes do it on the overrun as the car is decelerating. But the exhaust will garble so much it sounds awesome. You can really hear it if you are next to a wall or some parked cars. I didnt notice it before I did this mod, but I enjoy hearing it now!