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

[ORIGIN M.]

That valve helps to reduce scavenging in the intake manifold!

[jeremyc74]

Originally Posted by supraking

Just to clarify for everyone... DEFAULT (when the car is off) position of the flap is OPEN. When the car is started, air pressure is applied to the actuator through the vacuum hose, which in turn causes the flap to CLOSE. It REOPENS when increased RPMs and/or throttle load are present, and CLOSES AGAIN when revs/load drop back down.
.

No, the flap is open for a while after the car is started. There's a VERY obvious change in tone when it closes on my car. I've got catless DPs and I park in a garage, and there's no mistaking when the valve closes.

The valve is vacuum actuated, but it's controlled by the ECU through a valve that's mounted in the trunk. Pulling the wire off the valve will do the same thing as unhooking the vacuum line and plugging it.

[GtiGyver]

Originally Posted by jeremyc74

No, the flap is open for a while after the car is started. There's a VERY obvious change in tone when it closes on my car. I've got catless DPs and I park in a garage, and there's no mistaking when the valve closes.

The valve is vacuum actuated, but it's controlled by the ECU through a valve that's mounted in the trunk. Pulling the wire off the valve will do the same thing as unhooking the vacuum line and plugging it.

This is correct, in fact, above the amp in the left side of the trunk you can find the solenoid that the ECU uses to control the exhaust valve position. If you disconnect the solenoid as I did the valve stays open, no zip ties, no golf tee and no CEL.

The valve is in no way related to performance, it is only there for sound. Also, the reason why the engine is louder after a cold start is obviously in part due to the valve being open, but most importantly due to the engine using massive valve overlap to warm up the first bank of catalytic converters.

[Hind]

Originally Posted by GtiGyver

This is correct, in fact, above the amp in the left side of the trunk you can find the solenoid that the ECU uses to control the exhaust valve position. If you disconnect the solenoid as I did the valve stays open, no zip ties, no golf tee and no CEL.

Do you have a more detailed explanation on how to find this solenoid? Thanks!

[Hind]

Well even though this thread is old, reading it tonight motivated me to perform my very first mod. I had some black zip ties lying around, and VERY EASILY located and kinked the vacuum line. Anybody reading this wondering if you can do this, stop reading and go look under your car left of your muffler... I'll wait..... Now wasent that easy?

My impressions are as follows: I allowed the car to warm up before judging. For the record my un-modded car's exhaust valve is open while off, and at idle. Same with the golftee mod. Revving at stoplights I can hear a difference, it sounds more airflow is moving, and at low rpm speeds (10mph in 2nd gear) the exhaust hum is more noticeable, by a very small amount. Probably my most observed change is throttle response. The rev's (sitting still) seem to rise/fall a little quicker.

IMO a mod worthy of keeping for a little while, not to mention its free... and takes less time to do than to reach this portion of my review. Super freaking easy, if you can tie your shoe or breathe air you can perform this mod. Just try it, it was fun actually just working on my bimmer, even though it was for only like 8 seconds.

Thanks for this thread!

[BavarianMotorWorks]

I'm going to agree with the above poster. When I bought my 135i the golf tee mod was already done on the car. Well a golf tee was not actually used but a small metal clap that was keeping the rubber hose shut was used.

The moment I turned on the car on a cold morning I thought wow the exhaust is loud and sounds really nice. Driving around town though while keeping RPM's under 3k you get this "hum" as the last poster has said. It almost sounds like drone. You hear it EVERY time you press on the gas even a little bit. I actually thought to myself I highly doubt BMW would design the car to make it this loud just while cruising around while I have the gas pressed down just slightly.

So about 1-2 weeks ago I went under the exhaust part of my car pulled off the clamp and on my first cold start it was drastically quieter. That "hum" or drone if it is was almost completely gone. With the radio completely off it was a huge difference between the stock and with the golf tee mod. When I say huge difference I mean mostly under 3k of course. Over 3k I don't think there is supposed to be a difference but to me just because most of the time I'm driving around 3k rpm's or under I feel the over exhaust is just quieter even when pushing the car. Like I said probably just me but it just feels or sounds that way.

With the golf tee mod though driving around parking lots the exhaust is definitely louder up to 3k to the point where I've had some friends and co-workers asking me if I had an aftermarket exhaust. So I do like the quietness of the car now but eventually might go back to having the mod. The beauty is it is so simple to do the mod and then take if off later on.

[WhiteOne]

On cool mornings, when you can see the exhaust coming out of everyones tailpipes, only one of your pipes is working. After the golf tee mod they both are. It looks like you have a fake pipe.
I just pulled the line, put a BB in it and put it back on. It took 1 minute. No fake looking pipe for me.

[supraking]

Originally Posted by GtiGyver

This is correct, in fact, above the amp in the left side of the trunk you can find the solenoid that the ECU uses to control the exhaust valve position. If you disconnect the solenoid as I did the valve stays open, no zip ties, no golf tee and no CEL.

The valve is in no way related to performance, it is only there for sound. Also, the reason why the engine is louder after a cold start is obviously in part due to the valve being open, but most importantly due to the engine using massive valve overlap to warm up the first bank of catalytic converters.

Could you take a pic to show us what to disconnect? Not about to go tear out the wire for my brake lights haha...

[GtiGyver]

Originally Posted by supraking

Could you take a pic to show us what to disconnect? Not about to go tear out the wire for my brake lights haha...

Its the item highlighted in the pic although I heard that unplugging it will through a hidden code. By hidden I mean that no check-engine light will go off, but there will be a code stored in the DME about the flap being disabled.

[ad78]

^ this is only i believe for 335i not for our 1

[GtiGyver]

Originally Posted by ad78

^ this is only i believe for 335i not for our 1

What do you mean?

That pic is of a 1 series, and that solenoid does control the exhaust flap.

[ad78]

Originally Posted by GtiGyver

What do you mean?

That pic is of a 1 series, and that solenoid does control the exhaust flap.

did you try this on yours? i just did mine the old way..

[mineo77]

didnt notice any real change in the exhaust...putting on an axle back this weekend. It was fun getting under the car and checking things out.

[GtiGyver]

Originally Posted by ad78

did you try this on yours? i just did mine the old way..

I did it on mine, VERY noticeable from that (trunk) vantage point.
Although, I ended up plugging things up under the hood instead cuz I didn't want to through a code. I'm not sure how anal my dealer is, and no point testing them out...

[dugie]

I just did the mod, little difference..........not much. I will leave it for a while.

[GtiGyver]

Originally Posted by dugie

I just did the mod, little difference..........not much. I will leave it for a while.

Yeah, its only really noticeable when driving casually (when the flap would normally be closed).

[guydude]

i did this little mod on my auto/step 330i back in the day and it was cool, then i did it on my auto/paddle 335i and it was cooler--except at startup....when i would start the car it was so much louder that it kind of sounded like a tractor ......so know i debating doing it on my MANUAL <3 135 .....

[edgab]

just read this thread and i want to try this out. after removing the hose from the actuator, i read that by not plugging the actuator is fine. but if i don't plug the vacuum hose what will happen?

[GtiGyver]

Originally Posted by edgab

just read this thread and i want to try this out. after removing the hose from the actuator, i read that by not plugging the actuator is fine. but if i don't plug the vacuum hose what will happen?

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

[edgab]

Originally Posted by GtiGyver

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

thanks! just curious. will not be playing with fire.

[TreDirtyFive]

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 and there was some highway droning at 3K. I does sounds nice at startup though! Stays loud without one flap closing.

[chrisb321]

Originally Posted by GtiGyver

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

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?