Engine shakes

Hi and thanks for using 2CarPros.com.

Based on your description, it sounds like the engine idle speed may be too low. If you noticed this more when using the air conditioning, suspect a bad or dirty idle air control valve (IAC). This component is designed to allow a metered amount of air into the engine when at idle. Additionally, when the air conditioning or other load is placed on the engine at an idle, the IAC should allow additional air to enter to increase idle speed.

The IAC is located on the throttle body of the vehicle. I know this vehicle is a 4 gen 7 series, but I am not able to find the exact model in my manual. However, I have attached a picture or a 745i IAC to help you locate it. Also, you can read through this link which discusses rough idle and idle misfire.

https://www.2carpros.com/articles/engine-vibration-at-idle

Next, often times an engine vacuum leak can cause a rough idle and then is not noticed when the vehicle is moving. In reality, that should set the check engine light to come on and then a code indicating a lean fuel mixture or once specific to a component. Here are directions for checking for a vacuum leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know if this helps or if you have other questions.

Take care,

Joe

Okay this is a Euro car and does not have an ALDL connector like US based cars do. Also, this car does not have an IAC motor. Lets try doing a compression test to see if you have a low cylinder.

https://www.2carpros.com/articles/how-to-test-engine-compression

This guide can help as well.

https://www.2carpros.com/articles/engine-vibration-at-idle

Please run down these guides and report back.

Cheers, Ken

Thanks for the video really helps. It definitely is a mixture issue. This car is a diesel? Have you changed out the fuel filter lately?

Mixture meaning too much air not enough fuel that is why it run better when you remove the air. It is like it has a leak in one of the turbo intake tubes or a leak in one of the pressure tubes. Can you look using a flashing light to see if you can see anything? You might need to find a smoke machine and use that to find the leak.

Sounds good please let us know.

Yes, it can these engine have an air oil separator which is incorporated in the valve cover and it has other parts that go with the system as well.

Crankcase Venting System:

The crankcase vapors (a result of combustion blow-by gasses) are led out of the crankcase and back into the combustion chamber via the intake manifold. The blow-by gasses contain droplets of oil which must be separated. The oil is returned to the sump while the blow-by gasses are led into the intake pipe for combustion.

The engine performance is affected by the introduction of crankcase vapors into the combustion process, particularly in idle speed ranges. This influence is monitored by lambda regulation.

The crankcase vapors are carried from the crankcase and into the cylinder head covers through labyrinth separators (one per cylinder head). The oil which accumulates on the walls of the labyrinth separators flows into the cylinder head via a siphon and from there back to the sump.

The remaining vapors are passed to the engine for combustion via the pressure control valve (5) in the intake manifold. One labyrinth separator with a pressure control valve is integrated in each of the two cylinder head covers.

The throttle valve is controlled so that there is always a 50 mbar vacuum in the intake manifold. The pressure control valve regulates the crankcase pressure to a low 0-30 mbar.

The intake needs to be removed it looks like.