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Discussion Starter #1 (Edited)
I know this topic has been talked about a million times but I cannot seem to find a solution to my problem so perhaps someone can help. I hope :(

I have a 335xi sedan that I purchased last year from a second hand dealer. The car was great when I first purchased it. No issues at all. I changed my suspension to coil overs, my rims, and cut out the resonators and replaced with a straight pipe. After a while i would get on it and my Engine malfunction/Reduced power came up I got it checked out and all was well. I was directed to ignore it which I stupidly did. One cold morning I started my car it jumped to 5k RPMs and shut off i started it again and it stayed on but became very shaky. I drove my car which started smoking pure white smoke and shooting raw gasoline out of the tail pipes. I took my car into service. After having it for 3 weeks:mad::mad::mad: they ended up changing my spark plugs, fuel injectors, and "updated the software". I picked my car up today and it was driving fine! no shaking and felt more power. I was happy to believe my car was fixed until I got on the freeway and got on it a bit when my Engine malfunction/Reduced power light came back on. I asked my SA if there were any issues with my turbos or my HPFP and he told me they checked it out and no issues seemed to pop up and that this issue was strictly from my fuel injectors. I am all out of ideas and I am hoping someone has some type of advice. :dunno::dunno:
 

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Breaking in the Pony
2019 Mustang GT / 2005 Toyota Tacoma
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Get a code reader specific for BMW (i.e. a BavarianTechnic.com cable or the BMWhat phone app with Bluetooth OBD connnector).
Use it to read the error codes that are being set when the problem occurs.
Post the codes here.

If you don't do the above, anything we tell you is pointless guessing.
 

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+1 for codes.

The motor shooting up to 5k rpms at start up is a scary thought. I would suspect the throttle position sensor is going bad.
 

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1+ on investing in a code reader.....it will pay for itself in the long run.

Also go to your dealer and ask them to provide you with all the previous service records.
Also, on your last visit did the mention that you need your intake ports cleaned? Knowns as Walnut Blasting.
This is a very major cause of miss fires in our engines.

DN
 

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A cold start misfire on a turbo car is leaking fuel injectors 90%of the time , start cold , idle for 30 seconds or so , pull plugs and see if they are wet . If the car cuts out at highway speeds , most likely a fuel delivery issue . A high pressure fuel pump is the most common issue in a N54 6 cyl turbo motor . Carbon build up will mostly cause rough idle and knock faults . A bad low pressure sensor will also cause a rough idle
 

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A cold start misfire on a turbo car is leaking fuel injectors 90%of the time , start cold , idle for 30 seconds or so , pull plugs and see if they are wet . If the car cuts out at highway speeds , most likely a fuel delivery issue . A high pressure fuel pump is the most common issue in a N54 6 cyl turbo motor . Carbon build up will mostly cause rough idle and knock faults . A bad low pressure sensor will also cause a rough idle

Cured 3-4 years back - no longer an issue.

OP, where them codes? Or do you like to feel around in the dark?
 
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