I have had a cold-starting problem with my 2010 Golf Plus 1.6TDI (105PS CAYC engine) for about 4 years. The problem only occurs in the winter months so I believe it is related to the ambient air temperature (or humidity). Usually I only get the problem on the first start of the day after the car is sitting outside overnight. It happens between about October and April/May. During the summer there is no problem.
When I try to start the car it initially fires up OK, but then over the next 5 - 10 seconds the idle becomes unstable and then the engine stops. It does not respond to the throttle during this period. I then have to repeat this usually 3 or 4 times, but up to 10!, before the idle remains stable and the car is driveable. Subsequent hot or cold starts are then OK until the next morning, and the car drives fine, although sometimes slightly hesitant in the first couple of miles.
I have had the car checked a few times by the local main dealer and a couple of independent VW specialists. The following have been checked and eliminated:
- Main dealer said cold starting problem was not caused by EA189 update (2 years after update)
- Fuel delivery system and fuel pressures checked by main dealer (all OK), fuel filter changed as it was "dirty" (no improvement)
- It was suggested that the cranking battery voltage was low. I changed the battery - No improvement
- Scans on VCDS show no faults, the engine temperaure (coolant) reading was correct for cold start
- Glow plugs have been changed - No improvement
Current mileage is 113,000. The problem started at about 75,000 miles/2017 and is getting slowly worse. EA189 emissions software update was applied by VW in 2017.
This issue is driving me (& my wife) mad! I am not sure what to try next. A couple of ideas I had were changing the engine air intake sensor, or maybe the immobiliser is playing up when cold??
Any suggestions would be gratefully received!