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There must be someone who can tell me how the MPE on my 335ix is supposed to work.
I had an MPE installed by the dealer, BMW part, before I took delivery. It is a CPO unit.

I have been trying to find someone who can definitively tell me how to get the left exhaust pipe to open up. The salesman didn't have a clue.

I don't believe that the left pipe flap has ever opened. I checked connections and things appear to be tight. I gleaned from older posts that the flap opens up when RPMs are greater than 3000 and the transmission is in Sport mode or Sport +. Otherwise it stays closed.

Can someone shed some light on how it's SUPPOSED to work?

Thanks

Gary
 

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I gleaned from older posts that the flap opens up when RPMs are greater than 3000 and the transmission is in Sport mode or Sport +. Otherwise it stays closed.
This.
 

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Or disconnect it, add a jumper plug to make appear it's there software wise. Then open it manually and "pin it" to stay open.
 

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E93 335i, somewhat mod <> Fog City, CA
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I gleaned from older posts that the flap opens up when RPMs are greater than 3000 and the transmission is in Sport mode or Sport +. Otherwise it stays closed.
You're getting it....that's how it's supposed to work.

Would there be a reason for that? Yep! Back pressure and sa-mooth engine operation; torque development @ lower rpm.

Does it ever open? Um.....yes.....but as you're prob driving at the time you don't notice.

Should you force open? No, but some do as it's noisier. Low end torque will suffer.
 

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2020 Z4 M40i
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You're getting it....that's how it's supposed to work.

Would there be a reason for that? Yep! Back pressure and sa-mooth engine operation; torque development @ lower rpm.

Does it ever open? Um.....yes.....but as you're prob driving at the time you don't notice.

Should you force open? No, but some do as it's noisier. Low end torque will suffer.
Seen this before, can you explain it?
 

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Closing one of the exhaust tips does not increase torque. The back pressure argument is a flawed generalization. See below:

https://youtu.be/jjPeP_Nn2B4

Keep in mind that turbocharged exhaust systems produce minimal scavenging effect, if any. This is because the turbo impeller interrupts the wave patterns within the exhaust system. The next best option is to increase the maximum flow rate, hence catless downpipes and larger diameter piping.
 

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2020 Z4 M40i
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Closing one of the exhaust tips does not increase torque. The back pressure argument is a flawed generalization. See below:

https://youtu.be/jjPeP_Nn2B4

Keep in mind that turbocharged exhaust systems produce minimal scavenging effect, if any. This is because the turbo impeller interrupts the wave patterns within the exhaust system. The next best option is to increase the maximum flow rate, hence catless downpipes and larger diameter piping.
Agree with this logic, but was wondering what makes people so often state the torque loss thing.
 

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E93 335i, somewhat mod <> Fog City, CA
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Seen this before, can you explain it?
Well, the usual thing is that with better breathing [lower back pressure], more power is available. But BMW engines are tightly controlled and have an envelope of operation that allows only slight deviation from design spec. Reduce back pressure when the engine map is not designed to accommodate that, sub-optimal operation.

That was my experience when I did the 'golf tee' mod. What seemed at first to be smoother low end torque was simply reduced torque and when the exhaust flap was returned to normal op a pronounced increase in low rpm power appeared. I am persuaded by experience.
 

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Now if your experience was truly using a golf tee, then it was with an older model engine and possibly ECU mapping. As electronics and equipment have evolved so has the software. There might be different results now.
 

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Now if your experience was truly using a golf tee, then it was with an older model engine and possibly ECU mapping. As electronics and equipment have evolved so has the software. There might be different results now.
Yeah have to think about that or play with the coding & try to get performance measurements. Mine is coded open & the car is very strong out of the hole. Same with the 435.
 

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Now if your experience was truly using a golf tee, then it was with an older model engine and possibly ECU mapping. As electronics and equipment have evolved so has the software. There might be different results now.
'09....but I'm surprised if ECU mapping accommodates outta spec exhaust flap op. If anything, specs are tighter.

But I gotta be honest....thinking on it, JB3 may have been installed.....coulda magnified the issue, maybe caused it. But, not motivated to check. Happy with JB4 now. Flap is in operation.
 

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MPPSK and Keeping Exhaust Flap open

I have the M Performance pack installed, but use Carly for BMW Pro (New Version) to keep the flap OPEN in all driving modes. I do a lot of freeway driving, so it helps with power and efficiency to do this -- particularly in Comfort Mode.



##########

 

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I don't think the left side ever opens.

Sent from my iPhone using Bimmerfest
I have exhast soot build up in the tailpipes on both sides, so I am quite confident the left side does open under the conditions already mentioned.
 

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Of course you’ll have soot on both sides. I’m saying when the M exhaust is popping it’s only doing that on the right side.


Sent from my iPhone using Bimmerfest
 

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Can one of you exhaust conspiracy theorists explain to me why you think BMW bean counters - so tight that they would not even authorize felt flocking inside the dash cubbies on 2017 and 2018 5 Series - would sign on on paying for the valve, actuator, wiring, and programming if there wasn't a valid engineering reason for specc-ing them? Does anyone with a MPPK ever say, "Gosh, I feel like my car has 2 fewer horsepower today. That @#$%^&* exhaust flap must be closed again!" I know I've never had a complaint with the MPPK in our 340, and I'm amazed anyone here would.
 

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When I paid extra for the MPPK I wasn’t told that it (seems) to affect only one side of the exhaust.


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That's because it affects both sides. Always has. Always will.

 
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