2010 535i M-Sport Engine Knock Immediately After Start

[gstoltz5]

Car has 102,xxx miles on it and for the last 2K miles or so I've noticed the following behavior:

- I start up the car after its been sitting w/o activity for longer than about 5 hours

- While in Park, there is a slight "knock" and a tangible "jump" in the car that occurs every ~7 seconds

- When I put the car in D, the "knock"/"jump" occurs more frequently until I hit about 25MPH and then it vanishes for the remainder of the drive

- If I were to drive the car home from work, turn the car off and 20 minutes later come out to start it up, the aforementioned issue doesn't occur

Any thoughts on what this could be? I'm open to any suggestions, as me calling the sound/feeling a "knock"/"jump" is strictly my best guess; I'm not sure if its an engine or transmission problem.

If anyone has experienced this issue, they've worded it differently than what I've searched for as I haven't been able to find anything already out there for this issue; hence, I posted a new thread.

[AM330i]

Do you get any check engine light or reduced power, have you checked for codes. You will need a code reader that will show bmw specific codes, like carly for Android or ios, or inpa. Could be a failing or failed injector, coil or spark plugs. If you have an injector that is leaking, after you shut the engine down, it will continue to leak fuel into the cylinder. When you start it up it will cause that cylinder to missfire until it clears the extra fuel out. Easiest way to check for this is to remove the spark plugs and see if any of them are wet and smell like gas. Do this after it has sat with the engine off for a few hours. Your issue sounds similar to when I had a couple leaking injectors. Maybe if you can post a video of the problem, that could be helpful.

[gstoltz5]

thanks so much, AM330i.

i'm in the process of getting access to a code reader, as you suggested. I'd love to get my hands on INPA, but i haven't had much luck finding a spot to acquire it. any suggestions?

[Certified Amateur]

Experienced this on a customer's e60 n52 powered. Switched off AC, symptom disappeared. Didn't continue to troubleshoot as it wasn't in for that.