Gearbox notchy and mis-firing at idle

[Deleted member 37751]

I know it's not a Mercedes but it is German and this is the only forum i'm a member of
The Mark 5 VW Golf GT TDi 140 that I bought as a stop-gap until we get our *ahem* Discovery 3 is playing up.

The problem is that it will randomly not select 1st gear . The local indy who I have taken it to has checked the selectors on the gearbox, which are fine, the clutch and dual mass fly-wheel look new and he is reluctant to start dropping the gearbox & risking spending a lot of money on a car that I will be either selling or part-exchanging very soon.

The other problem is that when the car is sat at idle it runs a bit lumpy, as though it is 'mis-firing', yet when it's put on VAG com it is coming back without ant faults I've been advised that it could be the 'tandem pump' is on it's way out which could mean that oil is getting into the diesel..

Amidst all this, the car actually drives without fault; once in motion, it travels through every gear fine and the engine has got plenty of power when needed.

The mileage is 137,000.

Any thoughts would be greatly appreciated

 

[wemorgan]

Is it a DSG or a traditional auto? If it's a DSG then this post on a Lotus forum of al places might be of use.

I've worked for VW for 12 years mate so hope i can offer some insite.

The only issue with the DSG is the mechatronic control unit.

What happens is either it becomes very jerky, wont select a gear (usually 1st) or wont change up or down when it should.

This requires a new mechatronic unit, which is usually around £650 + VAT, and you will need about ah hour 1/2 labour, as you will need new oil (4 ltrs will fill it back up, but 6 ltrs is a full change, and it has a filter too, id do these at the same time) and as per most Auto boxes they need to be at the right temperature to change the oil.

You will hear some horror stories about them locking up etc, but in my 12 years and 2 different dealer experiences, iv never seen one do any worse then be very jerky ( and iv seen hundreds).

Bear in mind we see approx 5-8 DSG equiped cars per day, I have only ordered 1 new mechatronic this year.


It is not a regular thing, they do not fail after a set time, nor do they lock up or explode in great fashion - in fact apart from the odd mechatronic problem they have proven to be more reliable than manual boxes.

I order more manual box internals than mechatronic units.


From what iv seen, the main problem have been cars made in 2008, so I can only imagine there is a batch issue? Who knows, VW wont admit to anything.

But if it was me, I wouldnt worry, make sure it has it's oil and filter changed every 40k as it should, and don't worry.

If you have FSH and are a good customer VAG can offer a decent chunk of goodwill too, anything up to 90% iv seen.


I will add that most seem from 2008, though we have had near new ones fail, and of course old ones too, but it is very rare in reality - as said we rebuilt/replace more manual boxes than DSG's, its just as DSG is still fairly new, people will jump on the bandwagon to slate it, like the Passat R36 that had its DSG box lock up when doing about 50mph - a horrible thing to happen, but like anything something could always happen - it was a one time freak accident, where an internal part fractured - like a weak conrod could do in an engine for example.

So to conclude my essay () in my experience they are fine, a few have problems but dont listen to the gossip

 

[Deleted member 37751]

Sorry, forgot to mention that it's a 6 speed manual

 

[wemorgan]

I know this video is for a 5-sp but there might still be some relevance for your 6-sp.

[YOUTUBE]tp9ggefOjAE[/YOUTUBE]