Engine problem, help please

Hi Bimmers.

Thanks for helps I had before. I learned a lot.

Now I got another problem.

2002 320i automatic, 230,000km, family bought, not exactly textbook-maintained but did what's necessary in the car history.

But, first 180,000km was maintained by autoshop, and last 50,000km was my DIY. And I am new DIYer.



I've driven this car 100km+ per a day regularly in last 3 months or so.

Engine oil might need a change soon but it seemed its still okay, I added some more recently (using 5w-40 at this moment).



2 days ago I felt the symptom, I heard subtle noise from engine(?) when I am on the highway, then it seemed to went away.

It lasted 5~10 minutes.



Yesterday, on my way home, I heard this noise again 30 minutes before arriving home, then it seemed went away again.

It felt a bit more loud than first time but it was still subtle.



Finally 10 minutes before arriving home, it got obvious and I felt unusual vibration. I stopped the car on the side and opened the hood.

Engine is somewhat vibrating unusually but not so violently.

Engine noise is higher pitch sound than normal.

So, I can notice 2 symptoms. 1. Brittling vibration from engine. 2. higher-than-normal pitch sound from engine



It happens as soon as I start the engine.

It is worse when I put on more gas. (I could manage to arrive home but I drove carefully. )

In last 10 minutes of moving car toward my home, I felt it was getting worse.

Engine temp is normal.







This car has a pre-existing symptom.

Randomly stops on the road with all electrical warning signs, mostly when in lower speed like under 50km/h.

This symptom completely went away when I unplugged MAF sensor.

This car has been driven last 50,000km (180,000 to 230,000) with MAF sensor off.

In last 50km this 'random stop' symptom hasn't happened,

but it happened 2 times in last 5,000km.

I don't know it is related but I wanted to add more info.



Thank you guys.

Engine problem, help please