Hi all, I'm new here and I will post in the new member bit later. But I'm in a bit of a sticky one.
I've got a 2010 1.6 tdi golf s. Last Friday it broke down and when I hooked my cheapo diag on it come up with injector no4 open circuit. I got a vdo replacment from my local diesel specialist and the bolt from VW. Replaced it and had it coded thinking that would be the end of it. But it ran lumpy at idle. And hickupped a bit at 1500rpm when driving. After having it looked at by someone with vagcom we determined that no3 was reading high so thought that was it.
After replacing no3 and having it coded it still runs lumpy at idle and at 1500rpm ish when driving. It does pull ok though.
I took it to a garage who I've used lots before to check things out wondering if I done something wrong or the chap with vcds had. But they say all readings are ok. But they say they have had it when fitting vdo injectors not from VW and the only cure was to fit VW ones.
Anybody else had this?
The diesel specialist is trusted as we use them all the time for agri stuff. I'm £500 into this and really dont want to go and buy VW ones.
Anything else I can try?

Sorry for the long post. Thanks for any help in advance