Misfiring and Black Smoke running dog rough!!!

Hi new on this site and getting pretty desperate for a solution to my problem!
Got a Freelander td4(06) it started misfirring when warmed up only slight at first but got worse so i took it to a Mechanic who diagnosed a fuel injector fault so he checked them all and said all where faulty so changed all four anyway got the car back it was worse than ever struggled(and i mean struggled) to start would kick out white smoke whilst turning over and was still running rough!
So back it went The mechanic then diagnosed that the fuel injectors he'd put in where faulty(he'd had them checked) and 3 needed replacing so this was done and i got the car back!
At first it felt fine and was starting ok but after about 3 days the misfiring was back and now when you rev it over 2000rpms or go for a run black smoke is coming from the exhaust!
It went back in for the 3rd time only to be told he's re-checked the injectors and they are now fine he's done a 'compression test' and my no1 cylinder is knackered or not working and i'm looking at a new engine!!!
The work has cost me nearly £900 and the car is worse than when i took it in!!!
Not gonna name the firm on here because i will be taking legal advice!!!

Sorry for the long winded story can anyone give me any advice or info!!!
I did ask another person to look at it and he said the engine is fine and thinks the problem still lies with the injectors and has offered to test them!!!
Please help!!

realise you are quite a long way into this, but have you checked:

intercooler hoses for splits
egr for blocking
crankcase breather filter

all of these are simple checks for even the least mechanically minded, so you don't need to take it to the garage

good luck

As op says, but also check the fuel rail pressure sensor plug. The contacts can become dirty on the socket and cause running problems.

Cheers for replies had a reputable mechanic to have a look and he thinks its still an injector problem! So he did a leak test and confirmed that one possibly two are leaking but recommended a proper injection test on all 4 with a firm he trusts so thats my next move! Hopefully he's right he seems to know his stuff!
Obviously if this is the problem and it gets sorted then i will be taking action against the bloke who has messed me about originally!
He definetely said my engine is fine and not knackered as previously diagnosed anyway still early days yet hopefully it will be sorted soon
Cheers B.J.

You'll normally find when an injector is on its way out it won't so much as miss fire but it will have a rasping noise until you rev the engine and or slowly take longer to start.
If you have a synergy unit connected......remove it or switch it off as this will kill a failing injector if set too high.

At last the problem is solved and you wouldn't beleive the fault!!!!
The mechanic took the head off and checked the engine thoroughly it is fine his mate checked the electrics also fine!
He decided to take the injectors out again to make sure they were 'seated' correctly apon inspection he found pots 1 and 2 still had the old sealing(copper) washers in so when the new injectors where fitted they where slightly standing proud and not firing correctly!!!!
This was the work of the previous idiot a so called specialist who told me my engine was knackered!!!!!
A simple thing like that has caused me 2 months of hassle but at least it seems resolved now!!!!

I'm glad you've got it running right at last.

The TD4 is a sturdy engine but needs to be looked after correctly - noy treated roughly by the numpties found at many garages.

Your case is more proof, if needed, that it's best do as much work on the car as possible yourself.

Then if it goes wrong - you at least know which numpty to blame - ha ha.

Lots of info on here to help you.

Just about everything that can go wrong with a Freelander has happened to someone on here, and we all benefit from shared experience.

Good that you came back and told us how the problem was resolved.

S.

Well thats what i thought mate if this helps somebody with a similar problem! Then good i'm sure someone else has had this happen such a basic mistake but an 'experienced specialist'(yeh right) should have detected!
Cheers B.J.