I bought a 2005 Mk2 Focus in January, it has always smoked a cold start and sounds quite lumpy, no issues on a warm start.
It doesn't take long for it to smooth out, there's no loss of power, pulls well, and once warm returns very good mpg (can get 65 mpg on a good run, short runs into town from cold only 30 mpg).
The glow plugs were replaced at time of sale as this was thought to be the issue, so I'm assuming they can be ruled out. Asked a local garage for advice they said the injectors may need testing and reconditioning (£80 each to be tested, £150 each to recon, plus VAT), or that the EGR valve may need cleaning. I've found another place (Diesel Bob, Preston) who can test injectors for £8 each and recon for £88 each, plus VAT.
I also contacted the garage I got the car from, they said they've experienced many 1.8 TDCIs which loose the coding on the injectors, they said this can be sorted very easily and fits the issues I'm describing. I'm now living in Perth and I bought the car in Penrith so not close by.
I've read forum posts by others who needed injectors replacing, most of these found the car was running poorly when warm not just at start, anyone with similar experiences?
Really grateful for any information or advice!