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      07-24-2021, 05:36 PM   #1
jvivlemore
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Question F39 Rough Cold Start/Idle & Stall & Lack Acceleration Issues, Dealer Can't Diagnose

I purchased my 2018 X2 XDrive in May of 2020 with around 54,000 miles. When I first purchased the vehicle during my first oil change I had a BMW dealership due some type of computer reprogram because it was shifting hard between gears and didn’t feel normal. That reprogram fixed that but then in the fall of 2020 I started getting a new issue.

On cold starts if I tried to put it into drive less than 30 seconds after starting the vehicle it would idle rough and/or rev up and down to the point the car was shaking then stall out. It only stalled a 1-2 times before I started letting it run for a little longer before trying to put it in drive. The issue above could also describe it as a 'jerking' feeling or off and on feeling of power when hitting the gas peda (while the RPMs also went up and down). If I let the car sit for 30 seconds it was perfectly fine. After one occasion of it stalling it threw a P050B code saying “Cold Start Ignition Timing Performance” according to the Autozone scan (Dec 2020 with 63K miles). It cleared itself within 24-48 hours.

My hope was the spark plug service that I just did at around 72,000 miles on my last oil change around 65,000 miles would fix this problem but it hasn't. I'm at around 72,000 miles now and the issue is still present.

In addition to that (not sure if it’s related) I'm also experiencing hesitation when accelerating especially when doing a smooth acceleration from a stop or even trying to pass a car on the freeway. It's not everytime but when it happens it's very noticeable. It almost feels like the gas pedal isn't doing anything when it happens during acceleration then it finally starts trying to catch up or that ‘off and on’ feeling of power and no power then power again. This issue seems to be more noticeable if I accelerate while taking a turn (say at a street light).

I've posted on a FB group of X2 owners and everyone seems to think this is ECU related and a software update would fix the cold start issue. I've read others having the same issue and that resulted in a fix. No one seems to have the second issue that I'm experiencing though which concerns me.

To complicate things I spoke with the dealership who just did the spark plug service and a computer reprogram is not covered under my Powertrain+ Warranty so I'll be out the $250 to “try that”. $250 is a small price to pay for a fix but I don’t want to blindy waste money on one either if it’s something else.

The dealership couldn’t find any codes or issues when it was in for service last month and of course they couldn’t replicate the issue either. The issue when driving where I have issues with the power when accelerating may have even increased.

Does anyone have any idea what might be causing this?
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      07-24-2021, 06:19 PM   #2
Caravaggio
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Do the BMW techs have a flight date recorders to connect to the PCM that either the car owner or tech can drive with that's more extensive than the cars onboard computer that stores codes ?
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      07-24-2021, 06:35 PM   #3
jvivlemore
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Quote:
Originally Posted by ScottSinger View Post
Do the BMW techs have a flight date recorders to connect to the PCM that either the car owner or tech can drive with that's more extensive than the cars onboard computer that stores codes ?
I'm not sure personally but that sounds like a good question to ask both dealers near me. The dealership I plan on visiting next is the one closer to me and the one who did the first computer reprogram. I just don't want to spend hundreds in "diagnostic/service visit" fees for them to go "everything is fine" or randomly go "this may fix it" and it doesn't. Trying to avoid the rabbit hole/money grab especially since one dealer basically threw in the towel already and wants me to bring it back to look again even though they said they found nothing on the last visit.

I definitely want to have a tech ride with me though and then swap seats. While the cold start issue won't be there most likely at that point the acceleration should definitely be noticable.
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