Cd 220 Cdi 2001

[John Kerr]

Hi All.I have posted a few times on the lack of power problems with my W203 220 CDI.After changing all the relevent sensors,Mas(twice) turbo transducer,MAPS,MATS,I finally got the power back by replacing the Pre-Cat.The problem that still remains is when it gets to operating temp it goes flat at 2k and will not rev above 3k.The first reply is going to be MAS,is it going to be that simple.The first one i bought off Ebay from a guy who said he had bought it for his car but it turned out not to be the problem so he was selling it on,this was genuine Merc.The second i bought from ECP same as Merc only difference being it didn't have the Merc logo.
The last time I had the codes read only thing that came up was a stored fault Boost Pressure Low.Any ideas on any other sensor that could cause this problem or do I bite the bullet and buy another MAS, from the dealer this time.

Many thanks in advance

 

[R2D2]

John do you drive nicely or do you give it a good run frequently?

 

[John Kerr]

The car gets plenty of welly at times.There is a hill just outside Folkestone on the way home and most times I get half way up then the revs will drop to 3K as if a limiter has cut in.Would like to get it sorted so I can fit an SB.

 

[Dieselman]

It sounds like the ECU is selecting Limp home mode after the boost pressure is found to be too low.
The pressure is measured by a MAP sensor and the boost is controlled by the modulator. If your car has a VNT check the vane ring is moving properly to alter the turbo speed.

Check all ducting and intercooler for splits or leaks, a split may only leak under full boost.

You may still have an exhaust restriction stopping full gas flow.

Just go back to basics and connect a boost gauge to the MAP sensor line and preferably a pressure sensor into the exhaust down pipe.

 

[John Kerr]

Many thanks for the reply Dieselman.I have checked the ducting and intercooler for leaks all ok.I did try to take the inside out of the middle cat but couldn't get the mesh out,it looked as if it was stainless steel so my mig welder wouldn't have been able to weld it back up if I had cut it open.Maybe this is causing a restriction.Can you tell me if you should be able to see the lever move on the turbo if it's reved up.I asked my indie this and he said it has to be under load ie car moving.I find it strange it only happens when car reaches operating temp,as if a temp sensor is causing it.

 

[R/T.E49]

There was a "service measure" which involved lubricating the turbo linkage as they do sieze up. WD and then a graphite spray over the top.

 

[FLIGHTLINER]

Hello John, At least I am not alone with this DANGEROUS problem. I am a high mileage driver (50000+ per annum, miles not £), sedate and snappy, depending whose on board! My chauffeuring colleagues all suffer this problem. This is my second MB, 1999 E270cdi (imported) and now 2002 S320cdiL, and I have suffered this problem on both cars. The S is not reliable enough, but THIS problem is causing my colleagues and myself so much grief, we are all bunking off to Audi A8Ls