Hi there, 

I've got an issue with my 2012 focus 1.6 tdci, on acceleration at around 40% throttle or so, it begins juddering. It's recently had an oil and oil filter change, new fuel filter and a new injector. It's got 2 dead glow plugs which could cause an issue as I know it uses them under acceleration but I'm unsure about that.

Injectors 1,3,4 have got "injector offset learning at maximum" codes as well, idk if it's trying to richen or lean out the mixture but any advice would be greatly appreciated 👍

Change glow plugs and come back

Injectors are the Achilles heel of the 8v 1.6 TDCI.  Almost certainly them causing the fault.  Short answer is to put up with it rather than spend hundreds of pounds replacing them on a 10 year old car.

First I've heard of using glow plugs under acceleration.  They can be used during DPF regen though and the duff ones need to be replaced to avoid DPF issues further down the line.

5 hours ago, DaveT70 said:

Change glow plugs and come back

Yeah will do, the OEM glow plugs are denso aren't they? 

And from what I've heard from other people is that they are a pain to remove, they can snap the tip off in the head, if you have any tips on how to reduce the chance of that happening, it would be greatly appreciated 👍