Boxster Misfire - suggestions?

[shadrach74]

Legba,

I was thinking you might check the cats. I have heard of instances where a plugged exhaust can cause the symptoms you describe. Bring the car up to operating temp gently, then hit both the front and the back of the cat with an infrared thermometer. Exit temp of the cat should be much hotter than the entrance. I would also give the cats a vey light blows with a mallet and listen for loose particulate.

Keep us posted!

[Legba]

Some very useful responses. Many thanks.

Things have changed!

I now have both Fuel Sys 1 and 2 showing OL (open loop i believe).
STFT and LTFT all read 0% and do not change with load.
O2 sensors (pre-cat, my car does not have post cat) read 0.435v and do not change with load.

No fault codes are showing.

It was suggested to me that the car is now running on its basic mapping without any input from sensors. I have disconnected that battery for 24 hours to see it anything re-sets but without any result.