Engine Misfire

Hi Guys. I have a 1997 V70 T5 Auto. Over the last few weeks it has developed a misfire. - When the car is cold it doesn't seem to noticeably misfire regardless of how you drive it. - Once the car is warmed up if you drive it gently then it will very rarely misfire if at all. However, if you drive it normally then during any decent acceleration (i.e. overtaking) it will misfire quite badly. It seem to be at it's worse around 4000 rpms but it will misfire at other revs too. Any suggestions, should I start looking at the ignition system. If so, which component do you think is the most likely or could it be a case of replacing all? Thanks

How old are the spark plugs? Does the MIL lamp flash when the misfire occures? If so and possibly if not, then there will be a fault coded logged which should lead you to the offending cylinder(s).

Hi, Not sure on the age of the spark plugs as only owned the car for a few months myself. Will have a look at them first. No the MIL light does not flash when the misfire occurs.

Misfire 

I had an intermittent misfire on my S 70. It turned out to be a faulty HT lead. One of the plug caps had cracked and it was arcing to earth. I suggest you take them off 1 at a time and look for black marks. New set of leads is about 90 quid. Good Luck.

Plugs or air leak.... Very common issues on T5 engines... Jod

sporadic misfiring