Hi,

Stumbled across this forum and am hoping that those with far superior knowledge to me may be able to help with a problem I have!

I have a 2002 ST170 - got 97k on the clock.

For the past year, the car occasionally misfired - but only on long journeys and / or when the engine was very hot. The way to cure the problem when it occured was to drop a gear, and then slowly accelerate back up again.

A few weeks ago on a very hot day the misfiring was so bad it caused the car to stall. I called the AA out and they plugged their laptop into the car computer - no fault codes were showing. The AA man took a look at the car and believed the spark plugs and leads would need replacing. As he replaced them, he also discovered that the rocker cover gasket had split and was leaking oil into the spark plug wells - he said this would be the reason for the misfiring.

So I got the rocker cover gasket replaced (as well as the cambelt which was due). Picked up the car today and low and behold, after 2hrs of driving back up the motorway I could feel the engine misfire again. Only slightly this time, but noticeable. It is still there.

Straight onto the web when I got in and it appears this may be a common fault with the 2002 ST170's. The main problem is that it could appear to be any number of things!

Does anybody here have any experience of this problem and know what they did at the time to fix it?

I have an AA Warranty with the car so will be looking to get it fixed for free (fingers crossed!).

I should stress that when the engine is cold this problem does not occur at all - it is definately related to how long the car has been running on a journey and how much the engine has had to work in that time.