How can I fix my Volkswagen Polo misfire?

In March this year I privately bought a 2010 Volkswagen Polo 1.2 TSI. It was sold with a full service history, with 24K on the clock. It ran really well with no issues whatsoever.

After around six weeks and 3K miles it developed a misfire on acceleration which gradually got worse. A short time later whilst cruising on the motorway it lost power and four warning lights illuminated: engine management, traction control, EPC & tyre pressure.

On stopping and restarting the engine the lights went out and the car drove normally but the misfire gradually got worse over the next 1k miles and the four lights came on again three more times within a short period.

My local VW specialist hooked it up to his laptop and diagnosed a misfire on cylinder three. He recommended and fitted a new non-genuine ignition coil but this just made the problem worse so he replaced the original coil and insisted he change the plug leads with genuine Volkswagen parts. This did improve things but the warning lights illuminated the very same day and the misfire on cylinder three fault code returned - along with a misfire on load and at idle.

The specialist seemed phased by this but advised I drive the vehicle until it's next service (October) when he said he'd think about replacing the plugs and coil again.

Despite all this it averages 45mpg and is a good car. However, I'm irritated by this issue but loath to throw money at trying to cure a problem that many online forums tell me is far from uncommon but hard to diagnose and rectify. What do you recommend I do?

Asked on 3 September 2016 by wednesday48

Answered by Honest John
Only one coil? That's a bit unusual. All the engines I can think of for the past 10 years or so have individual coil packs for each combustion chamber. If your car is the four cylinder 1.2TSI introduced in June 2010 (www.honestjohn.co.uk/road-tests/volkswagen/vw-polo.../) then the problem is most likely to be a stretched timing chain because the quality of these varies widely due to VAG cost cutting: www.honestjohn.co.uk/carbycar/volkswagen/polo-v-20.../
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