When driving my C250 at various speeds up to 90mph everything is fine, as long as I accelerate slowly. However, every time I try to accelerate quickly using the kick-down, the car continually hesitates until I lift my foot off the accelerator. This happens regardless of what speed I am doing. I put the car into Mercedes last week and they could not find the fault even using their Star machine. I have tried petrol injection cleaner in the fuel over the weekend to no avail.



The car is a 2010 W204 C250 Blue Efficiency Sport CGi.
Can anyone help me please?

 

Could be a faulty accelerator module. It's quite rare for it to fail, but it does happen. Take a look at the link below - it's suggested to bring it into the dealer and not do it yourself.

Mercedes-Benz W204 Gas Accelerator Pedal Replacement - (2008-2014) C250, C300, C350 | Pelican Parts DIY Maintenance Article

 

Thanks for that. I will take it into the dealership and get them to replace the accelerator

 

Before you have them replace it, have them run the codes off the DTC; there are likely stored codes and that will tell them exactly where the issue is coming from. It could be something else entirely and will save you some $$.

 

The car began misfiring so often that I called out the RAC out to look at it. The fault was quickly diagnosed as a split coil on number 1 piston. According to the RAC mechanic this is common on some Mercedes, as any spillage when topping up with oil can leak down the side of the coil, eventually degarding the casing. The rubber collar around the neck of the filler hole was twisted, allowing any spillage to escape. Obviously, having only had the car for just over a year I had always been very careful not to spill any oil when topping up, so assume it was historical.I managed to get another coil from the Dealership for £50 and fitted it myself. The problem has now gone away.I have ordered another filler collar and will fit that when it arrives.

 

Glad to hear that you were able to sort out the situation. Please let us know if you have any questions or need assistance with parts in the future.