M40 316i cuts out while driving and idling (video)

[D.Martijn]

Hello,

I'm trying to diagnose my uncles 316i Baur.
Suddenly he noticed the car was stalling/cutting out for a sec while driving. Also idling the engine want's so cut out a fraction and keeps on running.

https://www.youtube.com/shorts/PpUxqnMXBhY

Anyone that has a clue what could cause this?
I've tried replacing the spark plugs (as they were due anyway) but the problem persisted. Could it be fuel related? I figured I swap out his fuel pump witch a spare one from my 325iX but unfortunately the connections are different.
After putting it back into the tank and starting the engine again, it's somehow a little bit better and not as frequent..

thanks!

[roguetoaster]

Independently check TDC1 and crank mark alignment, remove the ICV from the equation, consider testing the TPS and inspect the wiring right behind the connector.

Also, if it sits, corrosion on the dist/rotor.

Could also be a dodgy relay or power/ground connection.

I don't think there's a vac leak, but there is a mess of hoses under/next to the intake and an awful little o ring on the intake/throttle heat exchanger that cause issues.

Could of course be a fuel delivery or pressure issue.

[D.Martijn]

Independently check TDC1 and crank mark alignment, remove the ICV from the equation, consider testing the TPS and inspect the wiring right behind the connector.

Also, if it sits, corrosion on the dist/rotor.

Could also be a dodgy relay or power/ground connection.

I don't think there's a vac leak, but there is a mess of hoses under/next to the intake and an awful little o ring on the intake/throttle heat exchanger that cause issues.

Could of course be a fuel delivery or pressure issue.

I've replaced the timing belt and waterpump two years ago, it only recently started acting up.
While I did that, I also replaced all coolant/vacuum/fuel hoses, as well as the O-ring you're talking about

I guess I'll order some new parts like rotor and dist as I don't think it's ever been replaced.
And in the meantime I'll check out the TPS and wiring.

[roguetoaster]

I was thinking more that the harmonic dampener may have failed, they often do at this age, and is either clocked, or is moving out of position under load.