Idle speed erratic?

[150GT Passat]

Hi guys,

After four Octavias, I bought a 150BHP GT Passat estate just before Christmas, which I'm really pleased with so far.

However, over the last few days, I have noticed that the idle speed is extremely erratic, and even after driving 10 or 20 miles, surely enough to properly warm the engine up, when I stop, it will idle at around 1100 revs or even slightly higher. I've also noticed that the start-stop system wasn't always working. It's been much colder these last few days here, and today, with the temperature at around 2 or 3C, the idle speed always stayed above 1000revs. However, this evening, I went out for a short drive and noticed it seemed to be idling at a much more agreeable 800 revs even after a mile. The temperature had risen to 6.5C.

Has anyone else had these issues, and is it related to the external temperature?

Thanks in advance!

[technik]

Not had that issue, but the start stop won't work if the engine needs to generate extra power/electricity for the AC, heated seats, de-mister, wing mirrors etc.

By erratic, do you mean the it idles up and down or just that you've noticed the different rev levels at different times?

[150GT Passat]

Ok, that explains the start-stop bit.
Sorry, perhaps I wasn't clear enough with the idle speed. When starting from cold, it's around 1000revs, then I drive for a while and I'd expect the revs to have reduced to say around 800. But the last few days, if I pull up at a junction, even once the engine is warm, the idle speed hasn't reduced, and in fact has sometimes increased a bit.

[technik]

Probably worth getting it looked at. Mine idles below 1000 (even when cold I think).

Also, when the start-stop doesn't function, there should be the inactive icon on the dash display ( an A with a line thru it)

[150GT Passat]

Ok, thanks. I'll keep an eye on it over the next week, and then book it in. And yes, thanks for explaining about the start/stop, there is an A with a line through it when it's not functioning.

[150GT Passat]

Update, and how ridiculous can this be?

Took my Passat 150Gt Estate in to dealers on Tuesday morning. Got a courtesy car. Phone call Tuesday afternoon from dealer to say that they had put it on the computer and no faults detected. However, they asked if the master technician could take the car home Tuesday night just to check it over and see if anything showed up. I agreed, but was a bit frustrated, as several of my friends have looked at it and agreed that there's definitely something wrong as the idle speed is often above 1000 revs even when fully warmed up.
Wednesday morning- dealer phoned to say master technician agreed there was a problem. Hooray, I thought.
Phoned yesterday evening to see if it's ready to collect- no, still working on it. Fine, I thought, I'll keep the courtesy Golf. Today, Thursday, dealer phones to tell me they can't find a fault with it, computer says all ok. They have another, brand new Passat which they road tested and it displays the same characteristics. So, based on that, there's no problem!
Ha! NO WAY! So, after driving for 33 years, and never having had a car that revs in this way, over 1000 revs when warm, and having done more than 250K miles in the last 12 years in various Octavia 2.0 diesels, and a Seat Exeo, all with broadly similar engines, I'm to put up with this one that revs too high, just because they say another one does it, and even though their master technician admitted it wasn't right!!
ADVICE PLEASE folks?? Can other Passat B8 owners with 2.0 150bhp diesel engines tell me what their engines do please? What should I say to the dealer? I told them today I didn't want the car today, but will come tomorrow to see the other Passat to compare their idle speeds.
HELP!!