E-Class Coupe (C207) & Cabrio (A207) 2010-: E250CDI Coupe, E350 Coupe, E350CDI Coupe, E500 Coupe, E550 Coupe [Coupes & Cabriolets]

E350 Low idle speed on start up

Old Nov 29, 2020 | 04:10 AM
  #1  
Dans69's Avatar
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E350 (a207)
E350 Low idle speed on start up

Hi All,

My E350 (A207) used to idle around 750rpm I have noticed over the last few months this has dropped to around 550rpm. Idle is smooth but can cut out at times in reverse.

What I have found is if I blip the throttle after start up it idles as expected at 750rpm and stays like that until I start it again and have the repeat the blip of the throttle. its not idling rough at all and drivers smooth.
I have hooked up to scanner and no fault codes. I use fuel additives at every fill up. I had a terraclean service done about 2 years ago.

Could this be down to a bad glow plug or faulty injector ?

The car seem to run and drive fine when idling correctly.

Any thoughts or ideas would be very welcomed.

Many Thanks
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Old Dec 11, 2020 | 12:57 PM
  #2  
NimzE350's Avatar
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Mercedes e350 cdi
Originally Posted by Dans69
Hi All,

My E350 (A207) used to idle around 750rpm I have noticed over the last few months this has dropped to around 550rpm. Idle is smooth but can cut out at times in reverse.

What I have found is if I blip the throttle after start up it idles as expected at 750rpm and stays like that until I start it again and have the repeat the blip of the throttle. its not idling rough at all and drivers smooth.
I have hooked up to scanner and no fault codes. I use fuel additives at every fill up. I had a terraclean service done about 2 years ago.

Could this be down to a bad glow plug or faulty injector ?

The car seem to run and drive fine when idling correctly.

Any thoughts or ideas would be very welcomed.

Many Thanks
Have you checked the car battery? changed mine and stopped low/rough idle. If not most probably injectors.

Nimz
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Old Dec 11, 2020 | 01:08 PM
  #3  
Dans69's Avatar
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E350 (a207)
Hi Pal,

The Battery is new so I doubt it will be that. since I posted this one of the Glow plugs has gone bad so I am hoping replacing them will resolve the issue. its going in on Tuesday so I will report back.

Many Thanks Dan
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