Hi guys, i’ve recently started experiencing a problem with my Zetec S on 92k miles where the car is in limp mode and jolts, as if the turbo is actuating on and off constantly under acceleration from 2.5k onwards.

it initially threw a P132b:21 code, which i believed to be caused by a loose wastegate arm judging the wastegate %  readings from forscan, i replaced the vac pump check valve, which did nothing, so i ended up replacing the turbo hoping it would fix my problems but upon driving the car for the first time after this i then had a P0234 accompanied with a very noticeable jolt when joining the dual carriegeway, because of these conditions i then replaced the vacuum solenoid, which did fix the problem for a couple days but then one morning it popped a P0420, which i cleared straight away and i have now not had another code thrown for a week despite regular driving and it being in limp mode every time. i am now at a loss as to what to do. i have checked all vacuum lines for damage, but am yet to check the intercooler + hoses. 

the MAP and MAF sensors have been cleaned and inspected, all vacuum lines hold a vacuum and the air filter is clean. 

the turbo builds correct boost levels but seems to port them via the wastegate constantly in limp mode, which i suspect is causing the jolting/ juddering effect 

the car does have a cut in the exhaust where a back box was previously installed before, but now has an exhaust clamp, which i changed due to rust a few days before the problem started, and i believe is ever so slightly blowing. 

any ideas would be greatly appreciated! thanks 

 

each vibration shown on the graph is when the jolts are experienced 

 

DTCs: 

 

Check for wet belt damage and oil pump strainer restrictions