HELP!

[S2carsandy]

hello group. we have a s2. just recently it has been running really rough, on startup it ticksover had sounds good, but when getting warm/hot it it like it has constipation! the pressure has also blown off the backbox! we have put on a new cat, changed the cam angle sensor, and still no joy, any advice please, cheers Andy

[MPx]

If you've had issues with the exhaust ... then maybe the Pre-Cat has failed and is blocked? Tough one to get at to check tho.