CYLINDER4 MISFIRE

[MARCN7798]

hello,
i have recently serviced my boxster and when started up the engine light comes on,i have a diaognostic tool and states cylinder 4 misfire,i have changed the coil pack still no joy,i dont think its a plug but will change this also,any ideas anybody,
i have also just done the RMS and intermediate
thanks in advance
mark

 

[Glyn]

If you changed the coil pack to cylinder 4 you can rule out the coil, Change the spark plug, the plugs can break down under pressure from combustion or may be tracking to earth internally, Also check - and this is the most common fault - the electrical plug is engaged properly on the coil pack, unplug the the cable and refit - you need to push the cable on until you hear a click.
The plug can be pushed quite hard and it appears to be connected but unless you hear the click it will not make a good electrical connection and this will lead to misfire.

 

[Motorhead]

Hardly worth changing one plug Mark.

Why not try swapping plugs for cylinders 4 and 5 to see if the problem follows the plug, using your diagnostic tool. If not, as Glyn says, you're looking at chasing an electrical connection/cable problem.

Good luck.!

Jeff