Hi Henrik
We have that same VW engine in our Skoda Fabia - 1.2 litre, 77TSI engine.
What year was your car made? Earlier ones are worse for the timing chain, some modifications were made in production about 2012 to improve the situation. Our car is 2013 build, so the later production, but we still had to get the timing chain replaced at approximately 100 000 km. (car now has over 150 000 km and is still great to drive.)
You should listen carefully each time you start your car, especially first start of the morning. If you hear any metallic rattle / clatter sound then you should have the timing chain, sprockets, guides and tensioner all replaced as a set. We were told by the Skoda dealer that some metallic noise on start up is "normal" but an independent mechanic, a specialist in VW/Audi cars, suggested replacement was a good idea. Since the parts were replaced, the engine starts perfectly with no rattle or clatter noises.
The explanation I have read is that VW bought the timing chains in from a contractor, that contractor used old, worn out machinery to manufacture the chains, the clearances are too large and the chains stretch, eventually they are loose enough to skip over the sprocket and this destroys the engine when pistons meet valves. VW's modification included a new chain and a close fitting guard so that even if the chain is loose, it can't ride up off the sprocket. Doesn't stop the noise when chains are loose though, and continued driving with a slack chain causes other issues such as rapid wear of guides, which puts metallic particles in the oil. The opinions I read say that even the new chain isn't great quality, and better quality replacement chains are supplied by independent companies than the genuine VW parts. It is important to replace all the components - chain, tensioner, guides - as a set, the independent suppliers provide them together as a kit.
The other issue with these engines is the spark plugs are deeply recessed and the spark plug leads run very close to the exhaust manifold and turbo. The plug leads suffer from heat damage over time, especially that when parked, heat from the exhaust manifold, catalytic converter and turbocharger soaks up to the spark plug leads and cooks them. There was another modification in production, an extra layer of corrugated plastic, intended originally as protection against martens, was found to give a little extra heat shielding. This isn't a long term solution, the marten protection eventually becomes brittle from the heat and flakes off in small pieces. (At least here in Australia it does - and marten protection isn't normal on cars here, because we don't have martens, weasels or any similar animals.) The symptom of this problem is the engine suddenly falters, runs rough, stumbles, for brief moments, often when accelerating hard or up hill. This only happens for a couple of seconds here or there, other wise it seems fine, until... As the problem gets worse, the engine computer notices the mis-firing and shuts down fuel supply to that cylinder. (to prevent damage of unburnt fuel reaching the catalytic converter.) This leaves your car running roughly on 3 cylinders, engine management light and other warning lights will come on.
New spark plugs and leads fixes the problem, for now... but the new set will eventually get cooked too, so plug leads get replaced frequently on these cars. If you keep driving the car and ignore the misfire, the ignition coils module will be damaged and that makes the misfire even worse, and the solution more expensive. We have just had this issue for the third time - plugs and leads only, the ignition coil pack was fine. Fixed now and running like new. Oh, and plug lead 3, for cylinder 3, gets the hardest life and is usually the one that fails first.
Anyone know of others ?
