Asking this for my m8, 1.9tdi 110 Leon

He ran it very low on diesel at the weekend and when he came to it yesterday on start up it hunts up and down the rev range from around 1k to 750 and produces loads of smoke, after a few minutes it clears up and ticks over normally. It also does it if you turn it off and back on when it's ticking over normally. Checked it for any codes using torque and there's nothing confirmed or pending. Any ideas?

Unfortunately I'm not very clued up on diesels so haven't a clue lol

Sent from my GT-I9300 using Tapatalk 2

Black smoke ?

Sounds like could be over fuelling, change the fuel filter it may have sucked up some rubbish.

Also check for boost pipes come off 

It shows that you're not clued up; Diesels don't hunt!

 

Black smoke suggests over-fuelling, which suggests worn injectors, a dodgy map that's just turned up the fuelling above idle, or a Fleabay resistor mod.

 

It could also be an idle stabilisation issue, or the electronics that control the drive by wire generating a false throttle demand.

Sent from my GT-I9300 using Tapatalk 2