Misfires - Advice needed

[pcarine]

Hi All,
I've been doing a lot of research on this already, but just thought id throw my ideas out there and see what you all think too.
So, the 6N2 1.4 Polo, has been dropping power and chugging along a bit at low revs too.
I've read the codes myself:
P1348 - ignition coil power output stage 1 open circuit
P0301 - Misfire Cyd 1
P0304 - Misfire Cyd 4
The Cyd 1&4 misfires were re-occurring, and came back pretty much every drive after clearing the faults.
I also took it the the garage, who noted the above and also a crankshaft sensor problem and a low voltage battery.
There is also a lot of 'milkshake' type gunk from oil-water mix in my crankshaft breather pipe which returns to the air filter box (i'm assuming the separator unit on the engine body is also gunked up)

So.... i had the crankshaft sensor replaced by the garage, as the coil pack, leads and spark plugs were done about 2 yrs ago (and i can do these myself). It is still misfiring, so what to do next??
I'm planning on clearing out the breather unit and hose, then not sure where to proceed.

Would a low battery voltage cause intermittent misfires ? perhaps not feeding enough volts to the coil which feeds Cyd 1&4?
After reading bits on here i'm assuming a clogged breather unit may cause a rough idle but would it cause misfires?

any thoughts would be appreciated.
PC

[alexperkins]

Shouldnt cause misfires. Its gonna be a power problem

Bad earth on the DIS (coil pack) wont help, nor will a low battery voltage

[Aybesea]

I had same problem.To check voltage going to DIS take plug off and switch on ignition and connect volt meter to No 4 +and No 2 - on plug it should read above 11.5 volts aprox.I then got some wd40 and sprayed conections 1.2.3.4. and cleaned the DIS terminals with course wet and dry.then sprayed it again to get rid of dust.I then plugged it back in a few times.My DIS was a few years old going by the amount of road dust etc on it so i took the top off which is clipped on and cleaned those conections aswell.then put it back on.The HT leads looked nearly new but did not know how long they had been fitted so checked those.I put a meter connected at each end on conintuity and got no reading apart from No 4 lead.When the car missed fired going along below 2500rpm it was better but there was a still a misfire so worked out it must be ht lead No4 with the reading was wrong .Replaced HT leads and all is good Now if cleaning out the DIS connection had anything to do with it aswell not sure.