andyhyoung wrote: "I have seen skip loads of these Polos with the 3 cylinder kiss-of death 6 or 12 valve engines.They all have the usual misfires codes.Most have had everything bolted on or changed,from coils,injectors,sensors and even a reman Ecu!(how do they do that?).The bottom line is this is a nail of an engine that VW will not admit to being a problem.The only cars that seem to be ok,are those that have had timing chain/kit and a modified cyl head and software update,which realistically now makes these an economic write-off."

Jon Morgan writes: ditto - except in my experience the single cam is more prone to valve trouble - sticking & cracking with sporadic misfires & low compressions. The twin cam is more susceptible to lobbing the chain off, although the valves are also prone to issues. Software update for the single cam alters the fuelling profile & jacks the idle up. Software update for the twin cam unfortunately doesn't stop the chain being slung around the crank sprocket usually after an oil & filter change - leaving the workshop with some awkward discussions with the customer.
As Andy says - both these engines are amazingly crap.
P.S -I can't imagine the dealer got the timing chain diagnosis wrong - it takes 10 minutes to check the valve timing, knowing these lumps intimately it wouldn't surprise me if it managed to lob the valve timing a couple of teeth out tw*t the valves & also have an injector & coil issue thrown in for good measure