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      05-18-2020, 11:27 PM   #1
Fknid
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2014 50i strange engine behaviour?

Hi,

Just a question on the engine behaviour of my X5 50i 2014. When investigating an unresponsive accelerator pedal (or engine) I’ve come across this engine behaviour that seems very odd to me.

The video shows the data results from ISTA+ when lightly pressing the accelerator pedal when the transmission is in Park.

The highlights of the video are:
1. Engine doesn’t change from idle state until after 6% accelerator travel
2. Engine continuously increases rpm while pedal stays at 6.33%

This seems strange and I’ve not come across another car that has behaves like this. When the car is in Park it is impossible to keep the engine at a constant rpm. I’m wondering if anybody else’s 50i does this.

Last edited by Fknid; 05-19-2020 at 12:25 AM.. Reason: Try to get youtube embedded properly
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      05-19-2020, 08:39 AM   #2
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My 50i is definitely hard to keep the idle steady with the throttle held in the same position. Maybe a throttle angle relearn is the fix?
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      05-19-2020, 09:55 AM   #3
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correct me if i am wrong.

it is true that you cant really hold the steady rpm with same amount pressure on peddle.

i have tested my 50i as well, you have to really pay attention to control the force you put on peddle to have a "steady rpm"

however, i think it is because of the electronic throttle and bmw valvetronic.

your maf reading looks normal to me since that is what i am getting after changing the maf.

how is your engine perform at normal during cold start, idle, accelerate and decelerate?
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      05-19-2020, 10:06 AM   #4
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Sounds like the adaptive throttle BS. It's supposed to "learn" how you drive but instead is slowly changes what should be a linear throttle response into a bi-polar mushy mess. I am always resetting mine. I don't know who designed this system but they are not as smart as they think they are as it doesn't work. Reset your throttle and you will be surprised how much responsive the truck is for a week or so before it "relearns" to be slow again and I bet it will show a much more linear result in the test.
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      05-19-2020, 10:06 AM   #5
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How do you do a throttle position re-learn? Mine seems too touchy on my 50i, at times hard to drive smooth
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      05-19-2020, 10:19 AM   #6
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Quote:
Originally Posted by XXX5 View Post
How do you do a throttle position re-learn? Mine seems too touchy on my 50i, at times hard to drive smooth
Below is a link on how to reset, some say 5 seconds, some say 30 on holding the pedal down, I always did 30 just to be sure. This has worked for me on both E and F series cars & X's


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      05-19-2020, 08:10 PM   #7
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Quote:
Originally Posted by feven1026 View Post
correct me if i am wrong.

how is your engine perform at normal during cold start, idle, accelerate and decelerate?
Thanks for everyone's input. The car starts well every time, and idles ok most of the time - every so often is seems a bit shaky but that goes away within the first 30 seconds. Acceleration is fine once going, and deceleration is fine with no issues going back to idle ok.

The accelerator pedal seems to have a large "dead zone", where there is no engine response at all. When the car is cold (10-15 deg C) during slow take off the engine will respond only slightly and will appear to bog down during transition from idle to applying power to the wheels. This then results in quite a noticeable forward jerk as it seems the engine decides to up the power. It seems like it's about to stall and the engine tries to prevent this (I have no evidence that it is preventing a stall though, and it has never stalled, and no codes are ever reported).

Last year I reset all engine adaptations and there was a noticeable difference for the first 100 kms or so where the engine was perfect , but, it quickly adapted itself to run poorly when cold. When the engine is at operating temp is does run pretty well, and most times the jerking take off is gone. It is still better than it was, but not perfect.

My next step is to see if there are any small leaks in the intake system that could effect cold running performance and I also need to update the I-Level.

I have performed the TBA reset that is mentioned and I'm not sure if it does anything on this car. Hard to tell. I have performed it on an F10 535d and it made a huge difference.

I'll just keep reseting whatever I find in ISTA+ and see what happens. How bad can it be?
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      05-19-2020, 08:27 PM   #8
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Quote:
Originally Posted by Sophisticated Redneck View Post
Sounds like the adaptive throttle BS. It's supposed to "learn" how you drive but instead is slowly changes what should be a linear throttle response into a bi-polar mushy mess. I am always resetting mine. I don't know who designed this system but they are not as smart as they think they are as it doesn't work. Reset your throttle and you will be surprised how much responsive the truck is for a week or so before it "relearns" to be slow again and I bet it will show a much more linear result in the test.
I can't understand what the car is doing here when throttle input doesn't appear like it's linked to any actual engine output. Particularly seeing as the video shows the throttle angle increasing (whatever this means in BMWs accelerator-throttle-VANOS-Valvetronic arrangement).

It's good to know that other cars are the same.

My f10 diesel (535d 2011) doesn't do this at all and it should have all the similar systems. More accelerator more rpm, less accelerator less rpm; more predictable output. It drives more predictably as well.
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      05-21-2020, 01:46 PM   #9
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I have a '15 335i and over here perusing the F15 forum as I'm considering switching to a SUV.

This throttle adaptation crap is the single most annoying thing in the 2 different F30's I've owned (both N55). I also regularly do the reset and it has helped (for a week or so).

"The accelerator pedal seems to have a large "dead zone", where there is no engine response at all. When the car is cold (10-15 deg C) during slow take off the engine will respond only slightly and will appear to bog down during transition from idle to applying power to the wheels." This is exactly the same behavior as both F30s I've owned.

Does it behave the same when you put it in Sport mode? In my case, the issue isn't as apparent, but still there. Since I don't always like to drive in Sport mode (higher RPM before shifts), and it was annoying enough...I bought a BMS pedal tuner. It has multiple settings and so have found one that seems to be more linear most of the time.
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      05-21-2020, 09:00 PM   #10
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Quote:
Originally Posted by otay View Post
Does it behave the same when you put it in Sport mode? In my case, the issue isn't as apparent, but still there. Since I don't always like to drive in Sport mode (higher RPM before shifts), and it was annoying enough...I bought a BMS pedal tuner. It has multiple settings and so have found one that seems to be more linear most of the time.
I do think that the adaptations that BMW employ (for the most part) do a great job, but, I wonder whether in Comfort mode the engine adaptation is trying to achieve an emissions target rather than trying to achieve an acceptable engine response. However, I just don't think that my BMW responds the way it was designed and after a few years of sort-a trying stuff, I'm determined to get a solution. I had reported the issue to BMW when servicing the vehicle and got the "it's normal" response and they even had the gall to suggest that I might not know about Sport mode. It was that response when I decided to get the ISTA+ software and investigate it myself.

To answer your question - in Sport mode it still does it and it's actually more pronounced because when the engine response "kicks in" the jump feels quite a bit more.

I have considered an accelerator tuner device or even BM3, but, it just frustrates me that the car doesn't run how it should and I really want to solve the issue. I also am not convinced that an accelerator tuner would fix the issue.

I don't know that resetting any adaptations will fix it, but, it has made a difference so far so I'lll keep going. I don't think I can do any damage (I'll find out soon enough) and it does reveal something about the car each time I reset something (I do a lot of reading first).

Btw: Car was a second hand "executive driven" (read: BWM thrash vehicle) CPO (AUS equivalent) that had 7,500 km on it and I have owed it for 4 years. I have put about 50,000 km on it. As far back as I can remember it has had the issue to some degree, but, has become worse over time. For the first 2 years of its life with me it was serviced by BMW.

Last edited by Fknid; 05-21-2020 at 09:04 PM.. Reason: Make sure I write good :)
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      03-11-2024, 02:58 AM   #11
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Fknid I know this was so long ago, but did you ever resolve this issue? I'm losing my mind because I have to reset all my engine adaptations every 200-1000 miles to stop this annoying jerky acceleration from a standstill.

I'm begging you haha
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      03-12-2024, 12:45 AM   #12
Fknid
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Quote:
Originally Posted by sc77 View Post
Fknid I know this was so long ago, but did you ever resolve this issue? I'm losing my mind because I have to reset all my engine adaptations every 200-1000 miles to stop this annoying jerky acceleration from a standstill.

I'm begging you haha
I’ll have to assume you have an f15, for me these things helped:
1. Change transfer case fluid, and reset the transfer case.
2. I eventually had a coil go bad, and so I replaced all the coils and spark plugs. This made a difference as I suspect that I had a coil that was not firing properly. A code is only reported when ignition fails for greater than 200 cycles (according to my reading of doco in ISTA)
3. Transmission has “Neutral Idle Control” that is active in Comfort mode. This does delay slightly the engagement of the gear on take off from a stop. This can be disabled using after market flash or BMW.

I didn’t ever smoke test it, as I got it to a point that the drive was acceptable. I think the transfer case fluid change and reset had the most effect.

Good luck with it all.

Last edited by Fknid; 03-12-2024 at 12:48 AM.. Reason: Additional info
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