RPM Fluctuation

[MercedesEnthusiast]

Hi all,

Is the RPM fluctuation normal, on a W212 2012? When the car is idle the RPM fluctuates around 100 up and down, while driving no fluctuations at all but when steady it does even in P / D / R.

Any help is highly appreciated it.

Thanks

 

[MercedesDriver]

Hi all,

Is the RPM fluctuation normal, on a W212 2012? When the car is idle the RPM fluctuates around 100 up and down, while driving no fluctuations at all but when steady it does even in P / D / R.

Any help is highly appreciated it.

Thanks

It’s not supposed to fluctuate at all and even if it does it should be not more than +-10.
Are you driving it often with low fuel in a tank?
What kind of fuel you are using?
Have you changed the fuel filter recently?
Irregular idling can be caused by dirty clogged injectors so try couple of tank fillings with Shell V-Power maybe it will manage to clean all the fuel lines and the deposits on the injectors.

 

[MercedesEnthusiast]

It’s not supposed to fluctuate at all and even if it does it should be not more than +-10.
Are you driving it often with low fuel in a tank?
What kind of fuel you are using?
Have you changed the fuel filter recently?
Irregular idling can be caused by dirty clogged injectors so try couple of tank fillings with Shell V-Power maybe it will manage to clean all the fuel lines and the deposits on the injectors.

I've been using only BP premium, never ever regular Diesel and never drive it low on fuel. The fuel filter has been changed about 3k miles ago.

I'll switch to Shell to see if it improves. I've read somewhere about the fuel pressure regulator.