Hey all. Hoping some wise sages here can possibly help shed some light for me.

I have a Focus 2011 1.5 ecoBoost with about 77k on the clock.

Bought the car from a private seller a year ago and just had it serviced by a mobile mechanic I’ve been using for years. He did spark plugs, air filter, cabin filter, oil filter and oil.

After the service whenever I press more than about 20% on the throttle I get stuttering as it’s trying to build boost. I called my mechanic and he came back to investigate.

He rechecked the spark plugs etc and read the codes and it was calling out the turbo actuator. He checked it and saw that it had been converted to only use 1 wire. He observed it while the engine was running and it was behaving erraticly. He said it was likely someone trying to do upgrades and ran out of money as it had been required for the focus st actuator.

Go forward a few days and we fit the focus st actuator. Still the same issue. We then replaced one of the coils and it got slightly better so replaced all the coils. But no better.

After many hours he unplugged the MAF sensor and then the car, albeit with a warning light from the MAF being unplugged, drove perfectly. So I got the part number and got a new Bosch MAF and have just installed it. It went back to stutter under acceleration in gear 2 and up same as before. Worse if I shift into a higher gear and it needs more boost to pull.

I rebuilt the air box to check for air leaks and couldn’t see any issues, drove it again for a while but no better.

I then unplugged the MAF but now it’s doing the same thing as before (albeit slightly less)

I really don’t know what to do and would cherish any suggestions.

TIA, Aaron

Amendment to the above, it is the 1.6T ecoBoost

these cars have an awful reputation for self destructing - but even so if it was fine pre-service and weird after - you need to double check what was done

I'm wondering if one of the Plugs is faulty - no gap or ??? sounds like its a misfire just as it starts to try making real power

so - the turbo actuator being weird is a strange one - not sure about the wiring you mentions - all sounds rather strange and if that was wrong surely it would be throwing loads of codes all the time

the idea it was better with no MAF sensor is also intriguing - was the replacement really the correct part

if all the wiring is sound and it seems right with no error codes - compression test - and valve timing to discount some basics