Right guys, 2 issues with the car:

 

Issue 1: it is idling seriously weirdly, the entire engine is shaking a lot and is dipping below 10k revs, even as low as 4k which isn't great obviously. It's a 1.2 engine, 2003. After a bit of advice from colleagues I gave it a service, but the air filter wasn't right, instead of the sort of squint one the actual air filter was like a panel with a big loop on top of it. And this is issue 2: I can't find the filter anywhere, I work at halfords but I can't find it on any of our systems. I was wondering if anyone knows here to get them? I even checked K&N and they don't have them. Any ideas?

 

 

That's what the filter kind of looks like.

 

Thanks, Cameron.

http://www.ebay.co.uk/itm/New-genuine-VW-Polo-9N-Skoda-Fabia-1-2-air-filter-03D-129-620-03D129620-/271797009662?pt=LH_DefaultDomain_3&fits=Car+Make%3ASkoda%7CModel%3AFabia%7CCars+Type%3A1.2&hash=item3f485d3cfe

TPS or Euro car parts stock them. Check the air filter engine cover housing boot is not crushed inside the throttle like mine was

Ok, so my diagnostic tool arrived today and after a quick scan I discovered a P0303 code so my 3rd cylinder is misfiring. Next step is that tomorrow I'll try changing the fuel injectors on cylinders 1 and 3 and see if the fault moves to cylinder 1, any ideas

A) where to get a new fuel injector

if the problem doesn't move, what else could be the issue?

That was meant as B ) not

Most people tend to think spark first, rather than fuel, when misfires come along; but it isn't unheard of for it to be fuel-injector related.

 

If it were me, I'd have all three sparkplugs out first, to assess their condition/appearance/gap (post up photos if you're not sure). Then if they all look well, swap the coilpack from cylinder 3 to one of the others and check whether the fault moves or stays. Only if the fault stayed with cylinder 3 would I start thinking about maybe doing an injector move. Also with the 6-valve engine I might be tempted to do a compression test, to rule out more serious causes.

I'd be inclined to think it's the o2 sensor which controls your idle or icv, when the sensor fails they fail lean by design so car dumps in more fuel running rich which protects engine but doesn't revolve around stoich thus runs rich and tends to cause misfires this will also show up on your ltft and stft (fuel trims) so I'd look at your primary o2 sensor with Obd reader if possible.

It's an intermittent misfire caused by a failing coilpack as wino says, this is causing the bad idle as it briefly drops onto two cylinders. You may also have compression problems on number 3, it almost certainly won't be the injectors.

I slapped some new spark plugs in it 2 weeks ago, thought maybe it just needed a service to sort it. Turns out it didn't! I swapped what I thought was the coil packs (the black things on top of the spark plugs? on cylinders 1 and 3, scanned again and it came out still misfiring on 3, so is compression problem the next most likely?

I slapped some new spark plugs in it 2 weeks ago, thought maybe it just needed a service to sort it. Turns out it didn't! I swapped what I thought was the coil packs (the black things on top of the spark plugs? on cylinders 1 and 3, scanned again and it came out still misfiring on 3, so is compression problem the next most likely?

 

Yes. Get it checked.

sweet, there easy enough to do with a friend no?

sweet, there easy enough to do with a friend no?

 

If you have a compression gauge that will fit down the plugholes, yes.

Due to the age and what you've said so far, i'd go for the valves, exact same issues I had. My car would drive fine but as soon as it idled it would misfire on cylinder 3 and shut the cylinder down. Pain in the ass driving it to the garage.