Octavia 1.6tdi CR engine stutter at low revs

[Tiap]

My Octavia is sort of misfiring when revs are low, obviously a diesel so not a misfire but it is occasionally stuttering. It feels like it is juddering / pulling back when the engine is not under load. Dropping a gear so the revs are 2k or more then it drives fine again. VCDS is not giving any clues. Do you know what might be causing this?

[J.R.]

2 hours ago, Tiap said:

obviously a diesel so not a misfire

 

I would not be so fast to discount that possibility.

 

Others have the experience of the 1.6TDi, mine is just from reading what they post but there have been many examples of injector failures which indeed cause misfiring.

[StevesTruck]

If you've got vcds, it's worth having a look at injector quantity and fuel rail pressure live data, particularly if you can get someone to watch the data while you reproduce the fault.

 

An old-fashioned leak off test can also tell you a lot. 

 

Another suspect would be EGR valve needing a clean.

 

 

Edited 10 December, 2023 by StevesTruck

[Tiap]

Thanks for the replies. I had two of the injectors fail at different times but both when going up the same hill in Devon (Holden Hill on the a38. 70mph up a long and steep hill.) Both times the engine was fine one moment and the undriveable the next. Anyway the last time was a few years ago. 

Thanks for the advice Steve. I do have vcds and it is easy to reproduce so I will try that.

I have no idea about cleaning the  EGR so will need to look that up. 

[pikpilot]

 

1 hour ago, Tiap said:

I have no idea about cleaning the  EGR so will need to look that up

 

It is so difficult to get to the EGR on 1.6 tdi CR engine (engine code CAYC) that people usually just replace it once they have gained access.

If a garage does the work, most of the cost is labour.

[mac11irl]

injector dying.

had one go on my cayc during the summer.

 

if it was the egr, id expect you to be getting a flashing coil light and or eml coming up (as ive been getting for a couple of months) 

Edited 21 December, 2023 by mac11irl

[Tiap]

A quick update.

I had the local garage (not VAG) replace the EGR valve. They had it for 2 days before Christmas. The job cost £688 all in (parts, labour and VAT). 

 

It has fixed the problem, the car now drives like new.

 

Thanks for your help.