[SomewhereFull]

Hi guys,

I have a BMW 320d e90 2006 and about 7 months ago I started experiencing some issues with starting the engine.

First I though that because of the winter and because I was getting some glow plugs errors on OBD2 I changed:
- all 4 glow plugs
- glow plug relay
Also I have changed the battery (Monbat AGM 100ah), because previously I had some trash one non-AGM.

The issue disappeared but for some reasons it’s back and I thought this time it may be the Starter, so I fully repaired it - no luck .

I also took the key to a technician and he confirmed that there are no issues there, nor I am seeing the key error on the dashboard.

I am inserting the key and pressing the START/STOP button so all systems become operational (no starting the engine yet).
After waiting for about 10 seconds I am pressing the clutch pedal and pressing the START/STOP button.
- If it’s cold-ish, about 7-10 degrees celsius -> The engine sounds like it’s starting, it is cranking for about 1-3 seconds and it’s stopping, looks like it’s loosing power.
- Also, if it’s cold-ish, instead of cranking for a few seconds and loosing power -> It can continue cranking for a very very long time (and I am intentionally) stopping it.
- If it’s really hot, above 20 degrees celsius outside -> It will start without any issues (at least that is the case so far and at this moment).
- If I skip the first time pressing START/STOP to start all systems and instantly press the clutch and I am starting the engine -> Sometimes it will crank for a few seconds and loose power or it will continue cranking until stopped, or the engine will start like there is no issue. There are no rules, regardless of the weather/temperature outside.

* * * (Just as an extra info that might help) About two months ago I took the car to the shop to do regular oil change, filters, etc… and the guy told me the following that I have an issue with the engine.
The issue with the engine is with the Piston Rings (they need to be changed) and because of that there is extra (not low) pressure in the carter, and also burning oil more than expected.
Before I was told this information, the issue with starting the engine happened only once and that was about it.
Not sure if this is fully true, because I wanted to double-check with a more reliable technician, but if it’s true - I will rebuild the engine.

Maybe this two things are somehow tightly connected?
If not, what might be an issue?