Advice please: Rough/judder idle, no engine light, pulls fine.

[FirstTHP]

Hi everyone. I've got a 2010 1.6 THP with 58k on the clock, last serviced at 44k last year. When we bought the car it had an EML and anti-pollution warning. Gave it a few good revs and it cleared more or less right away. The car has plenty of power when driving, but at idle it's judders. Sometimes a little, sometimes very noticeably, sometimes not at all. No EML has ever come on though, and no other warnings on the dash. We keep blasting it down the motorway to maybe help.

We had the spark plugs changed 2 weeks ago which didn't help. We put fuel injector cleaner in also, which seems to have made things worse: judder at idle seems to be more frequent now.

One mechanic said the diagnostic said "injectors". He'd checked the coil packs by basically unplugging each one and seeing how much the engine faltered.

Another mechanic said

P2603 Electric turbo additional coolant pump control fault. open circuit
P1336 Fault misfiring on unspecified cylinders. Not characterised
P1337 Combustion misfiring on cylinder 1 fault. Not characterised
P1338 Combustion misfiring on cylinder 2 fault. Not characterised
P0313 Fault misfire detected during a low fuel level. Not characterised.

He says there's a blockage in the engine and it's "overfuelling", and cheapest option is engine flush and oil service. I'm not sure though.

I should mention the car runs just under 1k revs at idle. The needle sits below the 1k rev mark.

As I say, the car has plenty of power when driving.

Any ideas please? Thank you.
Also, the car is to sell so I can't afford to keep throwing a bunch of money at it.

[BeefMasta]

Timing chain or fuel pump most likely. Will also need walnut blasting if it’s never been done. Speak to Jamie at SP Tuning and he’ll be able to advise.

[BenS]

Idle revs-wise, about 1300 on cold start and about 700 when fully warm are normal.

[Chris_Blue]

HPFP and/or inlet valves need cleaning up

[FirstTHP]

Thanks everyone. Will look at the fuel pump and see.

[Chris_Blue]

accelerated my THP up a small incline on a triple carriageway, after having a few judders for a week or so, and really heavy juddering, then crawled off the carriageway, called RAC who didn't understand the fault codes, towed into Citroen and after about 10 days of trying everything they said the fuel pump had gone. Replaced it and all was fine. pricey to pay for tho, but mine was still in warranty.