What were the symptoms when MCS failure came on?. I had persistant MCS failure in my 1.9jtd 16v 156 sportswagon, I had owned the car from 5000 miles and probs started to occur around 180,000.....she was a great car and still is! however , when the MSC came on there was usually an instant loss of power.Some times you could catch it on the throttle and get power back but normally it would go into a sort of limp home mode and not go over 3000rpm. Stop the car and sometimes it would clear itself and drive normally, more often than not with the warning sign still on ! sometimes it might take days or a reset back at the garage.
At The Garage:
First thing replaced was the the turbo as it seemed that might be the problem, it could have been stripped down to see if the veins were clogged but was decided to have fitted an official Alfa recon turbo.All was fine for about a year , then the problem started again.
Back she went on the diagnostic puter and the EGR valve flashes up, we replace the EGR valve and all seems fine .........for a couple of months.....then same problem.
In she goes again, everyone scatching their heads now, back on diagnostics and another valve comes up, it is not suspected to be the culprit as apparently this valve only does something on start up ( I cant remember the name of it!) but it was replaced anyway to make sure......drove her home and up flashes the MSC failure again!
In to the garage again......this time the thottle assembly comes into question, a known working second hand unit was installed (new ones are expensive!) but no different!!
Back in garage again...diagnostics saying something about low pressure boost, then it is decided to wash out some valve to the manifold....drove her home and she felt like a brand new car!
However.........the problem returned a month later.....is the ignition barrell the answer? we shall find out!