Rough idling in 316i F30

[Jasper_tgx]

Hi everyone,

anyone have an idea any workshop provides throttle body & Idling Air Control Valve cleaning and roughly the cost? Currently car facing some rough idling issues. Intensity of rough idling is different as well.

1 - 3, 3 being most serious rough idling

Car in Drive w/ AC - 4
Car in Drive w/o AC - 3
Car in Neutral w/AC - 2
Car in Neutral w/o AC - no rough idling

Please advice. Do suggest if you think it may be other issues.

-Engine mount according to mechanic still seems fine
-Car do not have any check engine light
-New car battery changed as well

Thank you all that took some time to help!

 

[clemgoh]

Do not know your car model, age, mileage or engine type.

Rough idle is usually means the engine computer unable to adjust.... outside its ability to correct...
i.e. a mechanical issue.
for BMWs, Usually this is a vacuum leak, check your intake hoses and joints, or else check your PCV valve or PCV Hose, or cracked valve cover or gasket, or ignition coil or spark plugs, MAF sensor. Somehow unregulated air is passing in or out, beyond the DME control range.

 

[clemgoh]

Tips to Diagnose Vacuum Leaks in Your BMW

Read - https://www.ultimatebimmerservice.com/tips-to-diagnose-vacuum-leaks-in-your-bmw/

What is a vacuum leak?
When an engine runs, it creates a vacuum inside the cylinders. If a hose fails, or there is an issue with the engine, you may encounter a vacuum leak. This allows additional air to enter the engine, which results in an incorrect air to fuel ratio. These are the common symptoms of a vacuum leak:
Check Engine Light: If your car’s computer detects that you have a vacuum leak, it will illuminate your check engine light. This light may come on for a number of reasons. If the light has been triggered, take it to a technician, who can perform a diagnostic scan to find the trouble code.
Stalling: If the air-to-fuel ratio is incorrect, this can cause your engine to stall or die.
Trouble Starting: Having an incorrect air-to-fuel ratio can make it hard for you to start your car.
High or Rough Idle: If your engine is receiving too much air, it will idle faster than it should. Your car’s computer will compensate for the amount of air the engine is receiving. This will lead to fluctuation idle speeds.
Hissing or Sucking Sounds: If you can hear a hissing or sucking noise, you probably have a vacuum leak.

 

[clemgoh]

One simple check is to check Vaccum pressure first... here is one method I know from experience.
HOW to diagnose excessive Crankcase vaccum.

Check pressure by
1. there can be acoustic noise (when the adding OIL cap is opened). This noise is created due to a high difference of pressures (between crankcase and intake manifold), while the system tries to suck in the air via membrane to the inlet manifold. Still, the membrane has to be checked – the leakage is possible also via membrane rupture, not only valve;

2. opening the oil addition cap, excessive pressure can be observed. Higly increased pressure in crankcase is an indication of wasting of piston rings, pistons and engine block itself.

Good workshops will have a cap to replace the OIL CAP attached to a hose and meter to measure if your car has the right vaccum pressure.

The values for the right vaccum for the various engine models can be found on this last page here attached PDF - the Vaccum pressure specs in mBar … mine is N52 = 30mbar... don't have PDF for new engine models

 

[Jasper_tgx]

Do not know your car model, age, mileage or engine type.

Rough idle is usually means the engine computer unable to adjust.... outside its ability to correct...
i.e. a mechanical issue.
for BMWs, Usually this is a vacuum leak, check your intake hoses and joints, or else check your PCV valve or PCV Hose, or cracked valve cover or gasket, or ignition coil or spark plugs, MAF sensor. Somehow unregulated air is passing in or out, beyond the DME control range.

Hi Clem, really appreciate it for you taking some time to give me insights.

Car model 316i F30, November 2013, 100km, n13b16 egine.

Valve cover gasket changed at 85k mileage together with spark plug.

MAF sensor is the one located infront of the turbo, on the charged piped?

PCV valve and PCV hose, do you mean these

Intake hoses and joints, do you mean these

 

[clemgoh]

I mean this
The PCV is part of the valve cover. And has a rubber and spring to control vacuum pressure too. Can leak.
do check

 

[clemgoh]

There are many vacuum / air control hoses and components that needs checking
Better to go to workshop who knows.
Some vacuum pump gasket leaks can also affect vacuum pressures affecting engine performance. See attached diagrams