C240 Sport Estate misfire

[kieronf]

Recently my 1998 model has started to misfire first thing in the morning. I don't think it is a single plug issue, the engine just seems to fail to respond to the throttle. The symptoms can last for just a few yards of travel after which the power returns with a surge. The car is going in for a service soon so any pointers would be welcome.

PS - can someone advise of the best engine oil to use, the car has done 116k miles

Thanks

 

[grober]

How long since the spark plugs were changed??

 

[kieronf]

Hi there, I think they were changed in Sept 05 (these are the expensive ones aren't they?)

 

[grober]

plug type

How many miles have you done since the last plug change and what type of plugs were fitted do you know? do you do a lot of short journeys with the engine cold. maybe only need an "Italian Tune Up" ie driven long and hard with plenty revs to burn off any deposits on the plug tips.

 

[KLP 92]

I would be more inclined to say MAS sensor rather than plugs.

 

[kieronf]

Many thanks for your help - Yes I do use the car only for the school run mostly, albeit a chassis-testing sprint through 8 miles of Devon lanes. The problem only appears from cold and various reading suggests the Air Mass sensor could be at fault?

Cheers