Dimitar Yankov

For two months now when i start the engine and it is cold the RPM are fine and the idle is smooth. When it gets to operating temp. the RPM vary and idle it`s not smooth at all and goes up and down a bit and it`s very irritating. Have read some threads that say it can be the fuel pressure regulator. Is this the issue? What else can make the idle unstable when engine gets at operating temp?Car is W211 cdi 150 automatic transmission

rapidoxidation

throttle position sensor

Dimitar Yankov

There is no fault code.

Dimitar Yankov

1st i thought that its EGR problem and I've disconnected it, drove 2-3 day without it, problem is less noticeable but i know it's still there