I have a slight misfire on my Fabia SE TDI (90) – there's been an obvious misfire for the last couple of days when, driving at any speed, the accelerator pedal is lifted and the car starts to slow down.

The car is about 15 months old with 14,000 miles on the clock and from new has driven very well with no other problems.

Any ideas of what it could be and is the Dealer the obvious, and expensive, place to take it or could it be diagnosed at any decent garage?

Hello Rory, nice choice of car by the way!

Sorry to hear you have a misfire. Don't forget your car is covered by warranty and it should not cost you anything to get it fixed. But from your description, it does not sound like a misfire to me that is causing your concern. A misfire is normally only present if you have your foot on the throttle and pressing down. When you lift off the throttle the fuel supply is cut so no misfire can take place. A misfire is just that, some fuel is not being ignited under load and the engine misses a beat and you may hear and feel a misfire. Diesel engines rarely misfire under load as there are no spark plugs to malfunction. But there are other things that can cause something that sounds like a misfire when you lift off the throttle. For example, a sticking EGR (exhaust gas recirculator) can cause a popping/misfire sound under some conditions. If you lift off the throttle and you hear something that sounds like a misfire, that is normally an air leak of some kind making a popping sound or unusual thrumming, perhaps in the exhaust. Indeed it may be a small exhaust leak. Or it may just be that your car is trying to finish a regeneration of the DPF in the exhaust and your can hear a popping sound from that when lifting off. But if it's doing it a lot I would get it checked out as you may have a faulty DPF differential sensor causing the car to regenerate too frequently (nearly all the time on the last one I checked) which can cause a popping noise in the exhaust. If the sensor is faulty it doesn't normally show up as a fault on the dash either. A technician will find the fault fairly easily and put it right for you. I would advise going to your Skoda dealer for assistance and don't leave it too long in case the dpf is being stressed. Of course, it may be none of these things I mention. Without seeing the car I cannot tell. But those things mentioned are prime candidates, as are some other things I haven't. Good luck and please do post back with further information if you can once it's checked at the garage.

Edited 7 March, 201313 yr by Estate Man

Estate Man - thank you for your helpful reply.

I've booked it in to my Local Skoda Dealer for next week and will let you know the outcome,

Again thanks.

I took the car to my local dealer yesterday and with one of the Mechanics took the car for an extended drive.

Since I booked it in the car seems to drive much better, although still with a slight 'judder' when the accelerator is lifted after driving at speed (50 – 60 mph), but on the test drive it drove very well without any obvious problem.

The Mechanic discounted most reasons for any problems but surmised it might be the DPF regeneration that is occasionally causing it to 'judder' slightly after going at a regular speed and then de-accelerating.

Do you think he might be right?

He said the car drives just as well as any other Fabia he'd driven and if the problem does get any worse to get back to them.

I wondered, and as you realise I'm no great shakes as a car expert, that possibly the Diesel we had filled up with recently had been less than perfect and may have accentuated the problem.

As I said the car seems to be ok at the moment and I don't think it's going to break down any time soon so I'll see how it goes and let you know if anything goes wrong in the future.

Again thanks.

Hello Rory, thanks for posting back on this. Well, the tech could well be right about the DPF regen. That was always a candidate. But interestingly , I've had an enquiry or two from concerned diesel owners in the last two weeks about this very thing. Unfortunately, in my area in North Essex, there has been a bad batch of diesel causing hundreds of cars to experience rough running. It's been well publicised in my area on local radio and in the newpapers. It could be a similar thing in your area to perhaps. The upshot of all this is that no one has suffered any damage from the poor diesel, just rough running until a refill. Hope yours is ok from now on. Good luck!