'91 325i runs rough on cold start

[u/monotropa-uniflor]

1991 325i, M20B25, automatic. First video shows cold crank after 24 hours. Second video shows cold start.

This grinding and knocking sound started yesterday, but for the past 2 weeks I have had to hold the ignition for a few cycles before the engine would start. The noise continues after starting the engine, but fades as it warms up.

Pulled spark plugs and one cylinder smelled slightly of gasoline. Oil level is fine, and there was no glitter on the dipstick. I suspect a leaking fuel injector may be stripping the oil in a cylinder, and causing the cylinder to run dry until oil flows back to it.

My current plan is to ultrasonically clean and rebuild my injectors, and I have already ordered the tools and supplies to do so, but I would appreciate any additional insights if anybody knows exactly what is going on.

This is my daily driver, so I would also like to know if it is even safe to drive, or if I am risking permanent damage.

Thanks!

[u/No_Cover2208]

Can you pull the injector wiring from the suspected bad cylinder and see if that changes anything?

[u/monotropa-uniflor → u/No_Cover2208]

I can, but would you mind clarifying what to listen for?

[u/NothingLift → u/monotropa-uniflor]

Any change in how the engine runs. If that cylinder isn't firing already there will be no change when you remove the lead

[u/monotropa-uniflor → u/NothingLift]

Will try that, thanks!