2018 Leon 1.6tdi rough when cold

[smithy1216]

Hi everyone!
I'm hoping someone who's had similar issues to what I'm experiencing can help!
The car has done 130k but until recently ran spot on, in fact it still does once the engines warmed up a bit.
The issue is when you start it when it's been stood and the engine is cold.
Fires up without any hesitation but sounds rough, smokes a little and has quite a loud "diesel knock". Then when you start driving it hesitates and stutters until it either warms up or you floor it and it seems to "clear its throat'. Once warm the engines quiet, runs great, no smoke doesn't use oil etc etc.
No EML and no pending codes, and nothing really stands out when looking at live data.
Has anyone else had similar problems with this engine or can anyone suggest what to check or do as we're a bit stumped?!
Thanks

 

[Mr Pig]

I'm tempted to say that diesels are kinda like that. My wife's car was quite noisy for years but now it's nearing 50k it's running much quieter. Still a bit clattery when cold. They're not the most refined things.

 

[smithy1216]

I'm tempted to say that diesels are kinda like that. My wife's car was quite noisy for years but now it's nearing 50k it's running much quieter. Still a bit clattery when cold. They're not the most refined things.

Yeah I get that. I've had high mileage diesels for years and drive around 70k a year, but something is definitely amiss.
Noisy and clattery when cold I can live with, but the stuttering at low revs makes it almost undrivable until it warms up.

 

[Mr Pig]

Maybe it needs injectors or something cleaned out.

 

[smithy1216]

Maybe it needs injectors or something cleaned out.

I was leaning towards injectors but I'm no expert. 3 of the 4 look relatively new which is what's making me doubt it.
If no-one comes up with any other probable causes I guess removing them and getting them bench tested is a good starting point

 

[Mr Pig]

Have you scanned for fault codes?

 

[smithy1216]

Yes and read live data. Nothing at all stands out of the ordinary

 

[Mr Pig]

You could maybe try recording the sound on your phone and let a garage hear it. I've tried that before but they didn't get the diagnosis right.