intermittent engine knock on cold start

[andycoaching]

My 63 plate Rapid 1.6 TDI CR has an intermittant fault that only occurs during the winter. It normally happens when it is cold outside, as it is parked outside. When it does occur it can last for anything between 30seconds and 5 minutes. It sounds like a hydraulic tappet not filling with oil. The car has been serviced on time by Skoda, and has covered 36000 miles. It has been to my local dealer twice this year, but they cant hear anything amiss. It is currently booked to go back in in a couple of weeks for 3 days so they can keep trying it. The only other thing i think it could be is a faulty injector causing a diesel knock, but i am led to believe that the diagnostics dont show any faults, which in my experiance working on Cummins engines and their diagnostics would show up (i am a fully qualifed bus mechanic with 37 years in the industry. I am becoming concered as the warrenty expires at the end of September.Has anybody come across this problem before?. Thanks in advance for any help.Andy 

[James@RRG_Skoda_Rochdale]

Have them recode all the injectors and see if that helps.

[andycoaching]

Have them recode all the injectors and see if that helps.

Thanks James.Ive spoken to a friend of mine who had a chat with a VW master tech and he said the same. My local Skoda dealer doesnt want to know when i phoned with the info, and said that all the software is up to date. I suggested they asked VW next door to them (same company) only to be told that their software is completely different to theirs!!!

[sparky2]

My Wifes Spaceback 1.6 TDi had a problem once, she started it and it had a loud banging noise ! When I came home I couldn't find any faults and it hasn't happened since ! What do they do to 'recode the injectors' is it just a software update ? and if so would VCDS show the version ? cheers Stuart

[James@RRG_Skoda_Rochdale]

When the injectors are manufactured they run extremely fine tolerances and the way the machine deciphers this measurement is in the form of an alphanumeric code.

These codes are written to the ecu when the vehicle is built in order for the system to adapt correctly.

Over time though the ecu might not adapt 100% correctly so the codes must be re entered to reset the running parameters and iron out running issues.

The same goes for if they are removed, swapped from cylinder to cylinder or are replaced.

Fuel quantities are adjusted accordingly and it prevents unwanted side effects.

ODIS (dealer software) only tends to have the one brand installed depending on which dealer it's being used in, mainly due to license costs. So vw can only use it on vw, skoda on skoda etc - stupid, I know!

ODIS has the ability to code them and vcds may also but I've only ever used ODIS for it.

Edited 13 March, 2016 by James@RRGRochdale

[sparky2]

Thanks for that James, Its still under warrenty so I will have to book it in. cheers Stuart

[andycoaching]

The car was in my local Skoda dealer last wek for 3 days. They said that the software for the ecu  was out of date and they updated it. When i picked my car up all the service team had gone home except  for the receptionist. She followed me out of the showroom to go home and went in the opposite direction. When I got to the the car and started it it was knocking, so much for the software update. I will be picking my new to me car on thursday from a different dealer. I am getting a 1.6 diesel Octavia, deal sorted before i took the Rapid in. Thanks for all the info, very interesting.