E220 Cdi (1999) Gone Limp!! Need Help!

[ManJ]

Hi guys, got one to knack your brains over, Ive got a 1999 E220 CDI Avantgarde and seem to have a little problem...
Here goes: The car goes into limp mode after driving it for about 5 minutes, Star has diagnosed it as overboost...
Things changed without joy are:
MAF SENSOR
MAP SENSOR
EGR REMOVED AND CLEANED
TURBO REMOVED AND REFURBED

Still no joy, someone please help, ive been without my car for 3 weeks now... Garage guys are puzzled too...

 

[BlackC55]

Vacuum transducer?

EGR cleaning is not always sucessful BTW.

 

[ManJ]

EGR cleaning is not always sucessful BTW.

Do you mean I should try replacing it?

 

[BlackC55]

It is quite expensive just to replace (£270).

You need to be sure on the diagnosis first.

A vacuum transducer is also a common problem.

 

[ManJ]

sorry, vacuum transducer has also been done, and had a few split pressure pipes, which have been sorted, but still not cured... The garage has cleaned and checked the EGR and ive been told its not faulty

 

[BlackC55]

The egr is really the only one left to try.

Are all the vacuum pipes ok?

 

[ManJ]

vacuum pipes seem fine, bar the two split ones, next on the list is to check the intercooler... anything else I should put time into?

 

[BlackC55]

A split in an intercooler is normally vey obvious (loud hissing noise when accelerating)

Test the vacuum pipes for leakage even if they seem fine.

Your next step is to check the boost pressure when it is functioning for the first five mins. It will show the over boost if there is any.

If there is an over boost you then have to find out why and what is causing it.

 

[ManJ]

The pressure pipes are now in the process of being changed between turbo and intercooler, and tested, havnt had the car for 4 weeks... NOT HAPPY!!!
Fingers crossed this works now...