Exhaust valve fault 28i

JimsZ · Post by **JimsZ** » Tue Feb 23, 2016 3:22 pm

Any one have experience of this fault and the solution needed to remedy?

Have already checked out and replaced the (what appears to be a) solenoid in the boot. However the valve still does not work. We have voltage flowing through the solenoid now but it does not operate. Manual testing of the solenoid (providing a route to earth of the voltage and the solenoid operates correctly.

Suggestions welcome please.

Z4M-2006 · Post by **Z4M-2006** » Tue Feb 23, 2016 5:47 pm

Is the flap seized in the exhaust ?

Zed Five · Post by **Zed Five** » Tue Feb 23, 2016 6:11 pm

Is it stuck open? Or closed?

Check that you can move it by hand first.

JimsZ · Post by **JimsZ** » Tue Feb 23, 2016 7:05 pm

Valve flap moves fine

Z4M-2006 · Post by **Z4M-2006** » Tue Feb 23, 2016 7:24 pm

How many wires to solenoid ?

I dare say the earth and 12v feed are ok,but will also have a command wire for flap operation..

Im not sure if its a switched 12v or pulse width modulated feed... You need to monitor that wire to see what happens.

Maniac · Post by **Maniac** » Tue Feb 23, 2016 7:30 pm

If it's the same sort of set up as on my car, then the valve is operated by vacuum. The solenoid is simply a switch to enable or disable said vacuum. So don't discount the vacuum feed, it could be leaking, or the actual vacuum actuator could have a break in its seal and therefore the vacuum is compromised.

JimsZ · Post by **JimsZ** » Tue Feb 23, 2016 9:50 pm

A few more tests reveal the voltage is up to the solenoid but not operating the solenoid. Earth the solenoid and it operates and the exhaust valve works?

Sounds like a wiring issue some where... can any one point me at or does any one possess a link to a manual in pdf I could take a look at... maybe please...

Doesn't seem to be any available when I search?

http://manuals.co/workshop/bmw/z4/

JimsZ · Post by **JimsZ** » Wed Feb 24, 2016 11:27 pm

Still not diagnosed this yet but not had time to do any practical investigations.

Interesting read, suggests no harm in just leaving it disabled...

http://blog.bavauto.com/7886/bmw-3-seri ... 1-e92-e93/

If I were to have gone down the route of fitting a custom made aftermarket exhaust I would expect this to be eliminated, no?

Any thoughts from those more knowledgeable in these things...?

Maniac · Post by **Maniac** » Thu Feb 25, 2016 8:03 pm

Despite comments to the contrary it's singular purpose is to curb noise emissions. There is no harm in it being disabled.

JimsZ · Post by **JimsZ** » Thu Feb 25, 2016 8:44 pm

Yes I'd agree having read up quite a lot about it now. Some information suggests it's also designed to help with low down and high up the Rev range torque but info is conflicting. Lots of info on Beemer forums and Google suggest more to do with noise and aiding warm up of the exhaust CAT.

Also forgot I have a warranty with full cover so called them today and it's booked in for next week so hopefully get it working as it should under warranty.

Will keep you posted on the outcome.

Another example of the info out there, thread degenerates a bit along the way

http://www.bimmerfest.com/forums/showth ... p?t=476194

Many more when your searching for this topic

JimsZ · Post by **JimsZ** » Fri Feb 26, 2016 7:39 pm

Is this accurate and still applicable to the modern version,found on a blog post...

http://autorepair.about.com/library/faqs/bl104d.htm

BMW Active Exhaust System

Q. Hello Vincent, I have a question re the exhaust system on my 1996 BMW 328i, manual transmission, 83,000 km. In one of the two exhaust tips, there is a butterfly valve, which appears to be permanently stuck in the open position, although some time ago I “caught” it in a shut position.

I would much appreciate it if you would briefly explain (a) the function of the valve (regulating back pressure to optimize performance?) including what makes it move, and (b) how can I test it for proper function. Thank you for your time.

Regards,
Jiri

A. That is called the Active Exhaust System Actuator (AESA). The AESA consists of the following:

Exhaust flap with vacuum actuator
Solenoid actuator valve
Vacuum reservoir with check valve
MS 41.1 control module
The electrical function of the exhaust flap operation is controlled by the MS 41.1 module.

At idle speeds, up to 2500 RPM: the exhaust flap is closed with vacuum applied to the actuator. This causes the exhaust gas to pass through the long resonator pipe, reducing the low frequency noise that is generated.

Above 2500 RPM: the exhaust flap opens. This allows the exhaust to pass through the short pipe which maximizes the back pressure effect to provide the best performance.

In the event of electrical or vacuum failure the flap will rest in the open position providing maximum exhaust throughput.

MikeWoods · Post by **MikeWoods** » Wed Jun 12, 2019 8:38 pm

Did you ever sort this out? My 20i does the same thing, it sounds like the exhaust is blown on startup

The butterfly valve can be moved by hand
The solenoid has 12v to it on ignition

Does anyone know where the vacuum line that goes to the solenoid originate from under the bonnet (I assume it will be easier to check for vacuum under the bonnet)

Any ideas?

Smartbear · Post by **Smartbear** » Wed Jun 12, 2019 9:43 pm

MikeWoods wrote: ↑Wed Jun 12, 2019 8:38 pm Did you ever sort this out? My 20i does the same thing, it sounds like the exhaust is blown on startup

The butterfly valve can be moved by hand
The solenoid has 12v to it on ignition

Does anyone know where the vacuum line that goes to the solenoid originate from under the bonnet (I assume it will be easier to check for vacuum under the bonnet)

Any ideas?

The noise on cold start is normal, it’s to do with emissions-it’s also normal to be able to move the butterfly valve by hand.
Your car sounds like it’s working normally

Rob

JimsZ · Post by **JimsZ** » Wed Jun 12, 2019 9:56 pm

No, left as is and i have been through MOT`s with no issues so am happy to leave as is.

As Smartbear says don`t lose any sleep over it

MikeWoods · Post by **MikeWoods** » Thu Jun 13, 2019 8:14 am

Thanks chaps.

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