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      10-03-2013, 12:01 AM   #23
tturedraider
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Quote:
Originally Posted by Hawkensyco View Post
I myself am a first time BMW driver I recently purchased a new 2013 335i Xdrive with the sport 8AT transmission. I have about 500 miles on the car and from day one I have noticed this issues when you let off the gas and allow the car to coast the car downshifts from 3rd to 2nd you feel the engine braking and from 2nd to 1st you feel it again. I have done a lot of research and started multiple threads on the problem but have not be able to get a explanation for what causes this. Many people say they don't feel it others say they do some say that it gets smoother as you break the car in more some say to try and do the transmission/throttle reset which I have tried by turning the car on and holding the gas in for 30 seconds then turning the car off releasing the gas waiting about a minute then restart the car I did this and found no difference in the way the car drove at all. Others have said that there is some sort of transmission update the BMW services can do that will make it better but don't know if that is true. So I have no clue if the is just a common trait that all BMW's have or if it's something that I should be worried about.
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Originally Posted by floydarogers View Post
This behavior is entirely normal, on all BMWs with automatic transmissions since E9x days.

You have a turbo engine. All Turbo engines exhibit turbo lag if the RPMs get too low; downshifting allows the engine to remain above ~1200 rpm and keep the turbos spooled up so that max torque is available at all times.

Also, these modern transmissions (only the new Jeeps that have the ZF-licensed 8 speed have a "modern" transmission) pretty much keep the torque converter locked except in 1st/2nd gears. A locked torque converter acts much more like a manual transmission than older autos.

You have a "sports" sedan (other threads to the contrary). This behavior is entirely in that vein.
^^ This is the correct response to the concern of both you and the OP. The behavior you're experiencing is 100% normal for a BMW automatic transmission. It is frequently disconcerting to new owners who have never experienced this type of car. I would venture to say most of those who post that they don't experience it or don't feel it are reporting that because they have become used to it and no longer perceive it.

It is normal behavior and occurs in all automatic transmission BMWs across the line.
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      10-03-2013, 12:42 AM   #24
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That's a feature. There's nothing more annoying than ATs that insist on being in the tallest gear at all times, so when you need to get on the throttle you either have 0 acceleration, or the transmission needs to bang down a gear or three. It's so much nicer to control the car with a single pedal than to have to ride the brake all the time.

This is the reason I prefer driving a stick in traffic to most automatics, you can just control the speed with the throttle.
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      10-03-2013, 09:51 AM   #25
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Thank you guys you have been very helpful now I know I'm not going crazy and this is a normal trait that BMW has
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      10-03-2013, 06:04 PM   #26
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As a data point, I have driven a number of F30s. In my experience, the 328 xDrive exhibits the most jerky downshifting behavior, followed by the RWD 328.

This is not an anti-328 not anti xDrive observation. I suspect the engine type and driveline variant affects the degree to which this occurs.

This is not a "performance car" issue. Most sports/performance cars with ATs do not exhibit this behavior.
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      07-19-2020, 01:48 PM   #27
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2015 320i all of a sudden slows down automatically at high speeds

I was on interstate today driving about 80mph and all of a sudden the car feels like its braking for a moment then goes back to normal, the rpms falls a little bit but it drop my back about 5-10 mph then goes back to normal. I'm still on the gas pedal and no response at the time.. it feels like I'm braking but I'm not. it did this 5 times in a distances of 20 miles. please help. I have NO check engine lights or codes. bmw is stock. what can this be
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      07-19-2020, 02:19 PM   #28
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Quote:
Originally Posted by teclynx View Post
I was on interstate today driving about 80mph and all of a sudden the car feels like its braking for a moment then goes back to normal, the rpms falls a little bit but it drop my back about 5-10 mph then goes back to normal. I'm still on the gas pedal and no response at the time.. it feels like I'm braking but I'm not. it did this 5 times in a distances of 20 miles. please help. I have NO check engine lights or codes. bmw is stock. what can this be
was it raining? Could be the automatic brake drying messing up
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      08-27-2020, 02:40 PM   #29
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I can totally relate, I was actually looking to post an identical message for my 2017 440 GC. I purchased it a month ago with 29k miles. It's a blast to drive except in traffic under 20mph. I previously had a Mercedes c300, and you didn't feel a thing regardless of how little input you gave the throttle. I would say the BMW is too torquey at very low speeds, especially in stop and go traffic.
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      08-27-2020, 04:22 PM   #30
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Quote:
Originally Posted by BMWrules7 View Post
It is all about control. Instead of engine braking, think of it as the vehicle being tied to your foot.

When the vehicle can't maintain this control within the envelope, then we use the brakes.

BMW also knows that this extra control consumes fuel.

To combat this, there is a new program in some new models that defeats engine braking to the point of seamlessly, almost imperceptibly, placing the car in neutral.

This feature can be activated, where available, if you are in Eco Pro.

It is brilliant. When the system detects you with your foot off the accelerator, the vehicle silently shifts into neutral. The moment you touch the gas, the brakes, or transition to sport mode, or cancel Eco pro mode, the car silently shifts into the proper gear.

It's really cool. It is so seamless, you can only tell when the RPMs sink to idle.

Finally, use of engine braking gives you more control. Anytime you brake you are introducing a third party between you and the vehicle proper. Of course, braking is essential element. But, in general, braking should take a backseat in priority if the control can be maintained with just the accelerator.

Now, wear and tear is a different story. In the long run, it is cheaper to have extra forces be absorbed by a replaceable brake pad instead of the drive train.

But, if driving is your goal, then drive the vehicle the way it was designed. I would say 60% of owners don't keep the car long enough to where avoiding engine braking would be a huge benefit to durability and reliability.

How can I tell if my car has this feature? And how do I activate it?
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      08-27-2020, 08:46 PM   #31
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This is something I asked here a year ago when I first got our bmw, that it had negligible engine braking, it's down to the transmission and smoothness. I run my car hard practically every trip, and aside from a weird clunk when first moving in reverse, this has got to be one of the smoothest transmissions ever.
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      08-27-2020, 09:47 PM   #32
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Mine doesnt have excess engine braking...of all the cars I have owned, I feel this is one of the cars that has the least amount of it!
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      08-27-2020, 10:20 PM   #33
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I know I am out of place here, but you all should try to drive a 328d and see it's engine braking. You will probably find your 328i to be a smooth car. I can drive 40 mph in traffic, coming to a traffic light, and the car will easily slow down to 10 mph without a push of a brake pedal. All engine braking. Sometimes I feel people behind me think my brake lights are broken since I don't have to use them unless I need to come to a complete stop after car downshift to the first. Closer to first gear, the more engine braking. Diesel TDI VW with a DSG transmission has the most engine braking. 328d diesel with ZF8HP has quite a bit, but less than DSG. Driving a gasser with a regular transmission - the car coasts as if it in in neutral. I agree, best way to experience smooth coasting is to use EcoPro or manually put car into Neutral when coasting down, then it is smooth as butter. When in gear and especially with diesel engine, prepare to have your neck jerk a little as the car downshifts and engine brakes. You get used to it, nothing new.
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      08-27-2020, 11:37 PM   #34
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Quote:
Originally Posted by eugene89us View Post
I know I am out of place here, but you all should try to drive a 328d and see it's engine braking. You will probably find your 328i to be a smooth car. I can drive 40 mph in traffic, coming to a traffic light, and the car will easily slow down to 10 mph without a push of a brake pedal. All engine braking. Sometimes I feel people behind me think my brake lights are broken since I don't have to use them unless I need to come to a complete stop after car downshift to the first. Closer to first gear, the more engine braking. Diesel TDI VW with a DSG transmission has the most engine braking. 328d diesel with ZF8HP has quite a bit, but less than DSG. Driving a gasser with a regular transmission - the car coasts as if it in in neutral. I agree, best way to experience smooth coasting is to use EcoPro or manually put car into Neutral when coasting down, then it is smooth as butter. When in gear and especially with diesel engine, prepare to have your neck jerk a little as the car downshifts and engine brakes. You get used to it, nothing new.
All diesels are like that, very high compression = very strong engine braking
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      08-28-2020, 02:25 PM   #35
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Quote:
Originally Posted by 328iX View Post
All diesels are like that, very high compression = very strong engine braking
Diesel engines in our BMWs don't have good 'natural' engine braking. Like our petrol valvetronic engines, diesel engines don't require a throttle valve in normal running conditions. So no build up of vacuum caused by a closed throttle valve, which is what is necessary to resist free engine turning. It is not compression, but restricted pumping function (high vacuum) which provides engine braking.

Yes, valvetronic petrol and diesel engines do have a throttle body, but for other functions, (like DPF regeneration and shutdown in the diesel, idling and failsafe function in the petrol), not the old 'throttling' we were used to.

Gearbox software is going to have more influence on forced down changes and increased rpm, which adds to the frictional load on the engine.

We'd need a form of exhaust braking to get purposeful engine braking.
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