52 REG A140 cylinder 3 misfire

[adam1314]

Hello, guys
I have left my car outside for 4 weeks while I was on holiday. When I get back and drive it, the acceleration feels not even and the engine check light is on after driving a while.

The car behaves normally for about 20 minutes but after that, it shakes at idle mode and the acceleration is erratic, I assume one or more cylinder is misfired. If you shut it down for a while and restart the car, it behaves normally for another 20minutes and the problem will appear again. It also drinks more fuel than it usually does.

I did oil service at National Tyres and Autocare garage and they told me the cylinder 3 is misfiring and they are not sure where the problem are originated from. It could be the ignition coil, spark plug and etc. They recommend me to go to the MB Main dealer and have a check.

I plan to have a diagnostic check this weekend at MB Main dealer. I am wondering if you have any suggestions on this kind of misfire. And how much will Mercedes charge me for the diagnostic and repair?

I would really appreciate if you could input your ideas and comments. Many thanks.

 

[A140driver]

Could it possibly be a cylinder head gasket failure? Although I doubt it would lead to being ok, then suddenly feeling wrong again. I'll have a think and see if I can remember anything similar on our A-classes.

 

[BlackC55]

It is very likely to be a coil pack issue

 

[kwakdonut]

I'd go for coil pack too.....

Half an hour on Star will set you back £60-70 at a Stealers....

 

[adam1314]

some updates:
After leaving my car with edinburgh MB dealer, I got a call from them and they told me no problem was found. All cylinders work fine.
The edinburgh MB dealer is near edinburgh airport and I went there via city bypass. Maybe the high speed on the city bypass flush the humid away from the spark plug, coil pack or ignition coil.
I will see how much the stealer will charge me for the diagnostic check.

Many thanks for your inputs.

 

[adam1314]

some updates:
After leaving my car with edinburgh MB dealer, I got a call from them and they told me no problem was found. All cylinders work fine.
The edinburgh MB dealer is near edinburgh airport and I went there via city bypass. Maybe the high speed on the city bypass flush the humid away from the spark plug, coil pack or ignition coil.
I will see how much the stealer will charge me for the diagnostic check.

Many thanks for your inputs.

Mercedes charges me 1 hour labour for the diagnostic check. Although the labour cost is a bit higher, I have to say they are very professional.