Engine rough at 1100-1400rpm when just below normal running temp.

[Big carpy]

Hi,
I have an e320 cdi v6 2008 model. When the engine is fully hot it runs smoothly through the rev range. When it is warming up however (up to 1 bar below normal temp on the display) the engine runs really roughly between 1100 and 1400rpm only. It is like a misfire on 1 cylinder. It happens with the car moving along and also when revved in idle within this rev range. This is an irritation that I have lived with for 2 years and would like to solve with your help please. The car has done 140k miles, it has effectively had a new turbo (for other reasons), glow plugs and glow plug relay replaced. An indy has checked the injectors on STAR and said they were all OK.

Apart from this it runs sweet as a nut.

Any ideas?

 

[Big carpy]

Rough running and jerking on acceleration (limp home)

I have finally solved these problems (e320 cdi 2008 model) - no doubt others in the club had a look but couldn't help so I thought I would share my experience for the benefit of other members:-

Misfire at 1200 rpm
Checked injectors on STAR at 1200 rpm (misfire speed), three showed about +/- 2.5, the others were fine (+/-1). Had three new MB injectors fitted and misfire solved, mpg also improved to 42mpg on a run. Engine sounds and runs really smoothly. Interestingly at idle all injectors showed perfect readings.

Jerking on acceleration after a period of low rpm
What a pain this was! Car was violently jerking on acceleration, even pulling away from the lights was becoming a challenge. To cut a long story short -

I rebuilt the turbo CHRA and this had no effect other than bringing it back to new condition.
On advice from my indy in Rochester, Kent (who is excellent (truly 100% honest and great value for money) Mike at MB of Medway - 01634 813322, Unit 12, Castle View Business Centre, Gas House Road, Rochester, Kent, ME1 1PB, I have never recommended a garage but I do highly recommend Mike.)
I sourced a variable vane unit from Latvia and fitted it - It came from Nering and I paid express delivery and it was here in 11/2 days!
The unit was for a GT2056V turbo £100 and was beautifully made. I fitted it with all the new bolts and gaskets £50 from the stealer. Car runs like an absolute peach now.

Incidentally the injector problem seemed to be badly affecting the gear change from 1-2 and 2-3 to the extent that I though the box was going chips, however Mike did an oil change and the injector change and that was fixed.

Hopefully this account is some use to other members.