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Discussion Starter #1 (Edited)
A lot of you probably already know this, but thought I'd share for those who're struggling w/ odd hesitation from idle, weird / slightly jerky 1 - 2 gear transmission shift w/ low - mid throttle from idle, sluggish 1k -2K RPM engine performance.

Long story short: Had a sudden / hard MAP sensor failure that caused constant limp mode & a bunch of seemingly random codes on various air flow & emissions related systems (see below). After thorough diagnosis, as well as data points from various threads & forums, replaced MAP sensor to fix the limp mode & codes. Vacuum leaks, EGR issues, post turbo intake leaks, & other commonly reported causes were ruled out to not be root causes after further diagnosis / investigation.

The surprise after replacing the MAP sensor was how much it SIGNIFICANTLY improved low-mid throttle 1K-2K RPM power, and smoothness when boost starts to build above about 1.7K RPM. The vague / odd / weak feeling of a slightly slipping / stupidly high stall torque converter "feeling" in 1st gear to 2nd when at low - mid throttle, is GONE! I had attributed this funky transmission shifting from 1 - 2, to be the result of what is widely reported to be a poorly matched / tuned transmission from the factory, and / or leaky mechatronics seals, worn valve body, or worn pressure regulating solenoids. I've only logged 3.5K miles since I bought the car 2 months ago, so no personal reference point for how things should & could be performing...

After replacing the MAP sensor, I'm still not overly impressed w/ BMW's tuning of the transmission (nor have I ever been in any of my BMW's, nor any automatic trans, period); however, the annoying slight hesitation / jerkiness / sluggishness from idle is completely gone! At low - mid throttle, 1- 2 shifts are smooth & predictable, where the transmission no longer appears to be confused as to which gear it should be in and / or when it should have shifted. With low-mid throttle, 1st & 2nd gears pull smoothly, where torque linearly increases throughout the 1.0K- 2.2K RPM range until 3rd, 4th, etc with similar smoothness & effortlessness... Throttle response isn't as immediately sensitive & "fun" as my E46 (which is "touchy" by any standard); however, I no longer have to consciously push the throttle a fair bit & ease back out to keep things smooth & linear from a dead stop. Also, pushing on the throttle a bit when cruising at a low RPM in 25-60 MPH traffic feels incredibly effortless & is rewarded with a much more authoritative thrust to the back in sub 2K RPM's, without having to press the throttle down further to invoke a downshift to get the engine into high boost range. Engine tone is tangibly & noticeably different as well when getting up to speed at low - mid throttle.

Replacing this sensor may not fix your issues, especially if you have other issues going on w/ leaky & worn out stuff that has not been maintained / repaired... However, you might give this a try if you've done the work to ensure everything else in your intake & vacuum system is leak free & properly functioning, but still suffer from a vague feeling / sluggishness, as well as funky torque increase at low-mid throttle from idle, that occurs right when the transmission is trying to shift from 1st to 2nd gear... I thought my X5d was perfectly functioning, without any perceived issues; however, it appears that this sensor was not properly functioning well before it finally gave out & caused hard faults. I'd never have replaced this sensor without it dying in the manner it did, nor would I have ever thought it to be the root cause for what I've read was simply due to a bad trans tuning by BMW.

Fault codes for search function:

48DC - Charging Pressure Sensor, Plausibility
4C83 - Exhaust Pressure Before Turbocharger, Plausibility
3F25 - Charge-Air Tube Monitoring
4B82 - Exhaust-Gas Recirculation-Rate Control, Control Deviation
4862 - Air System, Air to EGR Mass Flow, Plausibility
3FF0 - Air-Mass Flow Sensor
 

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02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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Cold 1, 2 gear shifts are delayed for engine and transmission warm up.

That can be known learned by a close reading of basic BMW technical description documents available on-line here at Bimmerfest.
 

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Discussion Starter #3
Cold 1, 2 gear shifts are delayed for engine and transmission warm up.

That can be known learned by a close reading of basic BMW technical description documents available on-line here at Bimmerfest.
Yes, I'm aware of this. My E46 does the same thing for a mile or two... This is not new knowledge, nor is this what I'm referring to above.
 

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A lot of you probably already know this, but thought I'd share for those who're struggling w/ odd hesitation from idle, weird / slightly jerky 1 - 2 gear transmission shift w/ low - mid throttle from idle, sluggish 1k -2K RPM engine performance.

Long story short: Had a sudden / hard MAP sensor failure that caused constant limp mode & a bunch of seemingly random codes on various air flow & emissions related systems (see below). After thorough diagnosis, as well as data points from various threads & forums, replaced MAP sensor to fix the limp mode & codes. Vacuum leaks, EGR issues, post turbo intake leaks, & other commonly reported causes were ruled out to not be root causes after further diagnosis / investigation.

The surprise after replacing the MAP sensor was how much it SIGNIFICANTLY improved low-mid throttle 1K-2K RPM power, and smoothness when boost starts to build above about 1.7K RPM. The vague / odd / weak feeling of a slightly slipping / stupidly high stall torque converter "feeling" in 1st gear to 2nd when at low - mid throttle, is GONE! I had attributed this funky transmission shifting from 1 - 2, to be the result of what is widely reported to be a poorly matched / tuned transmission from the factory, and / or leaky mechatronics seals, worn valve body, or worn pressure regulating solenoids. I've only logged 3.5K miles since I bought the car 2 months ago, so no personal reference point for how things should & could be performing...

After replacing the MAP sensor, I'm still not overly impressed w/ BMW's tuning of the transmission (nor have I ever been in any of my BMW's, nor any automatic trans, period); however, the annoying slight hesitation / jerkiness / sluggishness from idle is completely gone! At low - mid throttle, 1- 2 shifts are smooth & predictable, where the transmission no longer appears to be confused as to which gear it should be in and / or when it should have shifted. With low-mid throttle, 1st & 2nd gears pull smoothly, where torque linearly increases throughout the 1.0K- 2.2K RPM range until 3rd, 4th, etc with similar smoothness & effortlessness... Throttle response isn't as immediately sensitive & "fun" as my E46 (which is "touchy" by any standard); however, I no longer have to consciously push the throttle a fair bit & ease back out to keep things smooth & linear from a dead stop. Also, pushing on the throttle a bit when cruising at a low RPM in 25-60 MPH traffic feels incredibly effortless & is rewarded with a much more authoritative thrust to the back in sub 2K RPM's, without having to press the throttle down further to invoke a downshift to get the engine into high boost range. Engine tone is tangibly & noticeably different as well when getting up to speed at low - mid throttle.

Replacing this sensor may not fix your issues, especially if you have other issues going on w/ leaky & worn out stuff that has not been maintained / repaired... However, you might give this a try if you've done the work to ensure everything else in your intake & vacuum system is leak free & properly functioning, but still suffer from a vague feeling / sluggishness, as well as funky torque increase at low-mid throttle from idle, that occurs right when the transmission is trying to shift from 1st to 2nd gear... I thought my X5d was perfectly functioning, without any perceived issues; however, it appears that this sensor was not properly functioning well before it finally gave out & caused hard faults. I'd never have replaced this sensor without it dying in the manner it did, nor would I have ever thought it to be the root cause for what I've read was simply due to a bad trans tuning by BMW.

Fault codes for search function:

48DC - Charging Pressure Sensor, Plausibility
4C83 - Exhaust Pressure Before Turbocharger, Plausibility
3F25 - Charge-Air Tube Monitoring
4B82 - Exhaust-Gas Recirculation-Rate Control, Control Deviation
4862 - Air System, Air to EGR Mass Flow, Plausibility
3FF0 - Air-Mass Flow Sensor
Thanks for the info. I believe when this sensor fails, the dde creates a plausible value based on other readings and uses that.
 

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Not the same failure but I once had limp mode on the highway to work. It struggled to do 65mph.
No boost shown on my torque android phone that's always on. At work, I popped the hood and saw the map sensor popped out of the intake manifold.
The grommet fell apart and just have blown out after the map fell out.
Used electrical tape to make a temporary grommet around the map sensor shaft.
It held for months until I replaced the grommet and cleaned the map.

Inside the map was crusted carbon that came out with careful use of a small screwdriver. Some contact cleaner spray in the hole and it was good as new!
Perhaps this is what killed your map. It might still be repairable, just be careful to not go too deep into the sensor.
 

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Discussion Starter #6 (Edited)
Not the same failure but I once had limp mode on the highway to work. It struggled to do 65mph.
No boost shown on my torque android phone that's always on. At work, I popped the hood and saw the map sensor popped out of the intake manifold.
The grommet fell apart and just have blown out after the map fell out.
Used electrical tape to make a temporary grommet around the map sensor shaft.
It held for months until I replaced the grommet and cleaned the map.

Inside the map was crusted carbon that came out with careful use of a small screwdriver. Some contact cleaner spray in the hole and it was good as new!
Perhaps this is what killed your map. It might still be repairable, just be careful to not go too deep into the sensor.
Kinda scary when it happens. Glad I wasn't on the highway during rush hour when it occurred!

My grommet was actually fine, barely harder than the replacement grommet. Still had plenty of plasticizer left in it to be reused if I wanted.

MAP sensor was pretty dang clean as well, just a bit wet from crankcase residue. Grommet was in the same condition. No CBU or crust inside the sensor's tube either.

Cleaned it with flux remover, acetone, & rubbing alcohol, as that's all I had at work - no dice.

Cleaned it again with throttle body cleaner when I got back home - no dice.

Replaced with new unit, working perfect.

On the way to work & back today (about 30 miles on the highway each way, w/ about 3 miles of "city" driving), noticed my MPG needle appeared to be a bit more generous with calculated fuel efficiency. Could be subconscious bias "wanting" to see it; time will tell whether there's been an objective increase in fuel economy. Perceived performance boost / smoothness in the sub 2K range is definitely noticeable compared to previous; can't quantify it, but it's noticeable & tangible enough to know that I'm not imagining it.
 
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