M111 engine lack of power issues.

[Wild1]

Hi Chaps,

I have a C200 Estate 2001 w203 the engine is the m111 1998cc supercharged version.
When I purchased the car last year my top speed was in excess of 135 mph and I could easily overtake another vehicle in 3 rd gear with ease. The car could really get up and go and was a magic car to drive.
Recently it started having some power issues where it would miss and splutter a bit especially when the petrol tank was over filled whilst driving and then also whilst driving all would feel great and fast then suddenly it would feel like we had dropped anchor I was pulling something heavy and this was was holding back the car.
My mechanic said it was the super charger so he changed that, but still no improvement, Then he said spark pugs so he changed them, then he said fuel filter and changed that, then he said fuel pump but I drew the line at that. He then said the supercharger hoses needed servicing but still no change.
I am ready to pull out my hair because I do not know what to do next.
Today I test drove it again and at half throttle I was at 100mph but it would not go any faster than that (on a flat straight road) however at that point there was a strong burning rubber smell that filled the car. I cannot see where it came from. At 80mph it is smooth and no smell but as soon as it reaches 100mph it will not go faster and the smell is back.
Acceleration is worse than my wife's little runaround, I have to drop to 2nd gear to overtake and still takes forever to build up enough speed to overtake.
What can I do next?
Is there any way to diagnose what is wrong?
The STAR checker shows no fault codes,
How to check the supercharger is working correctly?
What else could it be and how to check it?
I am sure my mechanic has no clue what to do and is simply just guessing.
I am at the pulling hair out stage right now. Can someone please help??

Stephen

 

[GeeJayW]

Need to do a compression and cylinder leakage test to understand if the engine is mechanically sound before spending any more time and money on it.

 

[Smart320]

Suggest you take it to a MB Indi and get it checked by someone who knows what they are doing, sounds as if your garage is guessing

 

[grober]

Sounds as if your fuel tank breather filter is choked and causing a partial vacuum in the fuel tank- this will cause a degree of fuel starvation which might explain your lack of power.
Your symptoms certainly point to a fuel starvation for one reason or another. Has anyone tested/monitored the fuel rail pressure?

 

[Wild1]

Thanks for the info The fuel line is what my workshop pointed to also but they were wanting to change the fuel pump. I stopped this because up until now like as suggested in one of the earlier replies I was thinking my workshop was guessing.
I could ask them to look at this.
Thanks for the suggestion.
As mentioned in the original post sometimes the car feels really fit and then just as I accelerate away it feels like wow someone threw out an anchor and the car looses all power and speed.

 

[tjamesbo]

could it be Mass Airflow Sensor ? usually shows itself as no kickdown etc and severe lack of power other than idling about at part throttle
but as said you really need a mercedes specialist independant on it and someone who can put it on a star diagnostic machine and correctly interpret the results as 1 fault can cause several other fault codes only an expert will know which one is the likely root cause of the other fault codes

 

[Wild1]

Hi guys I really appreciate your input for this. I realise what you say to be correct and true. I was hoping for some sort of suggestions which you have given me. My problem is I live quite aways from the city and the main Mercedes dealers. I live in the hills of Malaysia and some 3 hours or so drive to Kuala Lumpur. The workshop I have used is only 1 hour away so this is the reason for asking for suggestions. Malaysia is not like the UK and workshops are quite difficult to find a good one and a shop that actually knows what it is doing. this included even the Mercedes dealers.
However I take your points and will make the trip down. Thank you.
Another thing to add to my problem is on a morning in the cool air (17 degree C) the car has acceleration for a while until you get the sudden feeling of all of a sudden pulling something heavy then it is lost.
I will update this thread once I find the result.