C220 CDI Coupe - lack of power

[Stu Kay]

Hi All

I have been meaning to join the forum for ages.

I own a well maintained merc c220cdi coupe auto (2001)

I have had the car for the past 4 years and not had any problems with it until now!

I have had the car to a few garages about the problem with unsuccessful results.

The problems are increase use of fuel, i normally get around 50MPG but only getting around 43MPG (on a good day) around 60-70miles less on a full tank.

When the engine is cold you can put the accelerator pedal to the floor and it will change down a gear as normal and accelerate away.

When the engine is warm after 15mins or so, when are going around a bend or driving up a slight incline in a low gear, you but the pedal to the floor to change gear – nothing happens. This happens in all gears (a very slow increase in speed)

You want to overtake – you change gear by pushing the gear stick to the left (to change down a gear) it will only let you rev the car to 3000, it want let you rev over this.

It feels like the when you are pushing the accelerator pedal down its not opening all the valves.

The air flow sensor (i think its called this) has been changed 2 weeks ago.

Can some help??

Thanks

Stu

 

[jberks]

If it's lmiting you to 3000 rpm it sounds like safe mode, in which case the first step is to get the fault codes read. It could be a blocked catalytic converter, a dodgy replacement MAS (airflow sensor) or maybe an O2 sensor but without the codes you'd be throwing money at guesses.
The airflow sensor is the most likely, common and obvious cause which I guess, is why the garage have replaced it, but if they've done this without interrogating the ECU for the codes first, then they're guessing rather than diagnosing, and as such, are best avoided.

 

[Stu Kay]

thanks jberks for the quick reply. it is booked in at another garage next week. i will take your advice with me.

 

[HJHPH]

My wifes low mileage C220 coupe had exactly the same problem with it's previous owner, the pre cat had broken down blocking the main cat. MB replaced main cat but not the pre cat. We inherited the problem as the pre cat once again blocked the main cat after about 4k miles. Total cost to repair was £1600, however we did get a substantial contribution from MB after several firm letters.
If you have the same problem the car will start to make some odd noises as the exhaust gases force their way out from the sprung joint at the manifold due to the exhaust blockage.
Having been through this I would not drive it until it is rectified.

 

[Stu Kay]

Thanks for your reply, i have had the problem for around 3-4 months and have driven around 4k in that time. The car runs and starts well. No new noises from the exhaust yet!
With the noises did your car smoke alot??
Thanks

 

[Cole@MBS]

I would have to second the above fault as a high possibility, very common on that model!

 

[Stu Kay]

Does a warning light come on the dash board if their is a problem with the cat??
i have just clocked up 82k.

 

[Cole@MBS]

No there is not!

 

[nailer]

Hi there.
I have the same problem with 2002 C220 CDI at the moment.
It has no warning lights on but only lets the car go to 3000rpm at times! Other times it goes fine!
That is the strange thing when driving it wont pull at all up to 55mph. Then once you hit 55 ish it goes like a train. Up to 4000 rpm fine!

I have tried to get it plugged in but wont nobody will do it this side of Christmas.
I do have access to a garage and parts today though so any suggestions of stuff to try would be really appreciated.
We are trying the mass flow sensor and checking the exhaust as i speak.

Happy Christmas
Neil

 

[nailer]

Just to Update.
The Mass Air Flow Sensor appears to have solved the problem

 

[Cole@MBS]

Ah, good result there then, cheers for the up-date!

 

[Stu Kay]

Thanks Neil,

Did that fault appear on the computer fault finder?

I am going to change the mass flow sensor next week.

Thanks for your advise.

Merry Christmas

Stu