My skoda octavia vrs misfires when idle and when accelerating still after fitting new spark plugs and fitting 3 new coils. Still diagnoses cylinder 1 and 2 as a misfire even though new plugs and coils. Ive upgraded my dump valve encase of a leak, cleaned my boost pressure valve and tried redex cleaner. Engine light flashes when boosting hard. Ive swapped coils to try narrow it down but still cylinder 1 and 2 fault codes.

Please help!

The next step would be to check the wiring to the coil packs.

The next step would be to check the wiring to the coil packs.

also the n75 valve

and coolant temp sensor

Ive disconnected wires and reconnected. seemed to stop misfiring but when idle it constantly revs 1500 rpm by itself. still misfires when I put my foot down. I get about 2 seconds of boost and then nothing. even the noise of air intake sucking the air in stops!

if the revs are hunting at idle you most likely have a vac leak pre turbo. Check the Y shaped pipe at the right side of the rockercover as the first port of call, then the fun begins

You may also have shorting on the coil pack wiring. Some good write ups on how to remove and repair or remove and replace. I did mine with some electrical tape and made a huge difference, its surprising how brittle the cables get due to the heat from the exhaust manifold and the turbo.

Edit:

Just reread the OP and if the problem stays on 1 and 2 when you moved coils plugs etc then you are looking at wiring issues or compression. Hope its the former

Edited 20 February, 201115 yr by karlbar2k

You may also have shorting on the coil pack wiring. Some good write ups on how to remove and repair or remove and replace. I did mine with some electrical tape and made a huge difference, its surprising how brittle the cables get due to the heat from the exhaust manifold and the turbo.

Edit:

Just reread the OP and if the problem stays on 1 and 2 when you moved coils plugs etc then you are looking at wiring issues or compression. Hope its the former

+1 for coil pack wiring.

I had this on mine. It is caused by the turbo heat making the wiring insulation brittle and it cracks and exposes wire. That wire then can short or arc on the cover even if it is not in contact. I stripped mine back and reinsulated. I Then fitted a Audi TT metal heat wrap(std on TT's for the very reason of preventing heat exposure to wires) I have part number somewhere.

I then used electrical silicon grease to smear on the plug contacts (to improve connectivity) and replugged them to the coil packs

Fixed my problem..

Edited 23 February, 201115 yr by Bowders1

One of many along the way Bowders

Ive spoke to a mechanic and says to test the coils you can lift them out when the engine is running and you can see and hear the coil sparking. Ends up the first coil which was changed by the AA (45 bloody quid) was a dud. Thats why it keeps saying misfire 1 cylinder. Also said to be the likely reason why I can smell petrol in the engine. Ive ordered another coil to pick up from skoda garage. Fingers crossed!! Would this be the reason for the turbo boost backing off and then boosting again when I put my foot down?

Best getting a cheap VAG COM cable off ebay and using VCDS lite and reading the fault codes on the ECU.

I had this on mine. It is caused by the turbo heat making the wiring insulation brittle and it cracks and exposes wire. That wire then can short or arc on the cover even if it is not in contact. I stripped mine back and reinsulated. I Then fitted a Audi TT metal heat wrap(std on TT's for the very reason of preventing heat exposure to wires) I have part number somewhere.

Thankfully my coilpack wiring loom is still intact, but have been thinking about adding the Audi TT heat shield as a preventative measure... cos it sounds like a freaking nightmare to sort out.

Does this look like the part you bought?

Coil Pack Heat Shield - Part No. 8L9121659

Also came across this on ebay…

THERMAL REFLECTIVE HEAT SHIELD TAPE WRAP

Pros…

Probably a lot cheaper than the Audi TT heat shield.

May be some left over to wrap other heat sensitive parts

Cons

Not as neat or easy to fit as TT heat shield

Mmm, decisions, decisions.

Yes that is the part and you can still get it from Audi. I paid £18 i think.

It clips on with poppers and then sits into the std holes that the wire/cable runner plastic pins sit in. A neat job.

I guess the tape is cheaper and would do the job but is thick and not easy to fold around the wires as it is meant for exhausts.

If it was me I would pay the price for the audi part.

Chris,

I have a cheap ebay cable that works with VCDS Lite if you would like to come over this way and borrow it? I can even have a look with VCDS Lite if you don't have access to a laptop.

PM me if you want to go down that road.....(no pun intended!)

Martin

Hunting at idle and a petrol like smell will be a split somewhere in the breather hose though so dont forget to check like this one linky

Also check the pipes under the inlet manifold, mine split underneath the factory fitted sleeve that holds the two pipes together, impossible to see until sleeve was cut/removed, i found it by moving the pipes when engine running and could hear the leak.

Edited 24 February, 201115 yr by Stuboy