I have a 02 s40 1.8 sport whitch has developed a slight missfire, more noticable at low revs.
I have changed the plugs with NGK ones,the man in the shop and my mechanic said they are suitable. I have had fuel treatment to clean the injectors done, chnged the air filter,changed 1 coil which I have tried in both ports, and had the lambda sensor checked, all to no avail.
The engine management light has not come on and there are no fault codes stored.
Three mechanics have tried the car and noticed the missfire but are unsure what to try next.
The car has 48000 miles on it with a full service history. All the plugs were the correct colour when removed.
It can also be a bit of a handfull on cold mornings??

 

Has the throttle body been cleaned?

It still may be a coil.

 

Hi again thanks for such a promt reply. Cleaned throttle body tonight,still the same. My garage suggested leaving car with them overnight so they could restore factory settings for co emissions etc when car is cold??, Or do you think i should invest in asecond coil. My nearest volvo garage is a 3hour ferry trip and a couple of hundred miles drive away.

 

I would try to get another one.Swapping won't really tell you much.
Beside if one goes bad the others aren't far behind.

 

I changed the second coil and replaced the plugs for volvo ones last week, the car was running fine until today when it started 'kangerooing' and 'spluttering' again .Its now worse than before but still no fault codes??

 

How about the ignition wires? Will it affect performance? I understand for my 01 S40 only 1 of the 2 ignition coils has wires for the spark plugs, whereas the other one is direct. Don't know if its the same for the 02 model though.