Octavia 2011, 1.2Tsi petrol - Cylinder 2 Misfire P0302

[mfk]

Hi
Above car has erratic idle and slight misfire. Generally drives ok in higher ranges with full pulling power.

EML comes randomly on with P0302 code (Cylinder 2 misfire) and sometimes the Electronic Stability Control light as well. Changed plugs (long life) and leads but made no difference. Put a new coil pack on but it made no difference so have returned to the original one. I thought it was coil pack as 2 of the pins looked a bit corroded on original coil pack and 2 were bright shiny. Unless of course the new coil pack was faulty but unlikely I guess. Compression test is all fine.

It broke a chain 2 years ago at only 65k km so had a full head rebuild, new valves, chain and tensioner. Car was always serviced on time. Shortly after rebuild it developed a problem which turned out to be a sticking rocker arm so I had all of them changed too.


Any ideas what is likely to be the cause. Could it be an injector and is there a way to check the injector.

Appreciate any help or advice.
Thanks

[OldGit]

If there was corrosion on the coil pack pins, then there will be corrosion on the connector receptacles too, they need replacing - if for no other reason than to rule them out as the cause. Try www.auto-click.co.uk/

[valhalla]

Once you have sorted-out the harness connector into the coil-pack, and assuming this hasn't fixed the problem, the next port-of-call is a compression check and a borescope down the affected cylinder to look for scoring or any signs of piston-ring scuffing.

These engines are very sensitive to slight mechanical problems, and there's no margin for error on mixture-preparation, so anything affecting compression or intake port blockage/swirl-control is going to give a misfire under certain running conditions (part-load being one of them).

[mfk]

Hi
Thanks for the replies.
Sorry for any confusion. The corrosion I refer to is on the pins that the spark leads connected to on the coil. The wiring harness all looks 100%. I tried another NGK new coil and again no difference. I poured a drop of redex into the cylinder No. 2 and left to soak in case any carbon in there but again no difference. Also put some in tank in case it was a dirty injector but nothing so far.

A compression test was done and all confirmed ok.

When driving it today the TCS light came on dash as well with the EML.

Thinking next area is an injector. Not sure what is involved in removing but I think it may involve inlet manifold off.

Thanks again