Recovering from bore wash. Experiences, solutions, advice needed..

[Effduration]

I wanted to share my own recent experience with this.

My car: 2003 E39 530i 5-speed manual with M54B30 engine and 420,000 miles on original engine.

Summary:
-I have never experienced “Cylinder Wash” or “Bore Wash” before.
-I tried starting my car in sub-freezing weather after letting it sit for 7-10 days
-The car stumbled badly, like it was running on 2-3 cylinders – this had happened 1-2 times before.
-I immediately shut it down and tried to re-start 3x with no success. Car sounded like it had little compression.
-I did a compression test and sure enough had just 30 -60 psi on all 6 cylinders…way too low.
-I figured maybe I skipped a tooth on the timing chain – and was thinking I might just part out or scrap this 530i as I have other cars that need attention.
-but I pulled the valve cover and checked timing and it was perfect.
-So taking advice in e46 thread below -in particularly from MrMCar and JFOJ, I put 2 tablespoons of oil in each cylinder with piston at the bottom of bore.
-Cylinders are slanted, so I tried to get as much oil as I could around the highest part of the piston with a long tube.
-I also used compressed air to try and distribute oil around cylinder (a suggestion found here) and I heated up each spark plug briefly with a propane torch.
-Re-installed valve cover, plugs and coils and kept my fingers crossed.
-Sat in driver’s seat with a fully charged battery and cranked engine for approximately 60 seconds when it finally started!!
-The car stumbled, but did not stall…I was able to the feather the gas pedal to keep it going.
-The car produced so much smoke I thought the neighbors were going to call the cops..
-The engine stabilized in 30-50 seconds after starting. I drove it slowly around the neighborhood with temp shown on cluster until I reached full operating temp.
-Brought it home and after cooling, pulled plugs to clean any oil off them before reinstalling.
-Drove car again today to full operating temp. It now seems to start and run fine.

Cylinder wash IS a real thing and it happens when too much gas gets into the cylinder and washes all of the oil (and compression) out of the piston bore and rings.
In my case, my piston rings are almost certainly worn, which may have contributed to this issue, but there are plenty of posts from cars with less than 200k miles.

You won't ruin your cylinder bores if you catch it quickly.

I am running 5W30 synthetic oil from Walmart if anyone is interested.

Cylinder wash seems to happen in colder weather.

The thread listed below was a huge help in solving this issue:
https://www.e46fanatics.com/threads/...n-fix.1254795/

[crystalworks]

So what caused the wash? Leaking injectors? Was it running fine before sitting for 7-10days? Just curious.

[Effduration]

It was running fine before sitting. Although on occasional rainy days and after sitting for more than a few days - particularly in cold weather- it occasionally started with a bad mis-fire. Not sure why. In the past when this happened, If I shut it off and restarted it would run fine on the 2nd start-up.

In this case, I shut it off as soon as I heard it misfire. I then attempted to re-start it 3 times with no luck. Each attempted start was priming the fuel line and firing injectors, but since there was no combustion, the fuel was just washing away the oil in the cylinders.

I do need to find out why I have the occasional stumble on start-up in cold or wet weather.

The injectors were recently (last 6 months) refurbished and tested.