Thread: its dropping a cylinder

Well you know its usually spark or fuel. Pull the plugs and look for one that's a funny colour. A crook insulator will go conductive when hot and misfire. A funny rusty colour indicates water in the cylinder, oil fouling from a bung valve stem seal can also cause problems.

The dissy cap may have a carbon track from a contact inside, polish the cap properly just in case.

Then there's injectors, a dirty or loose plug will lose contact as it heats up. The hotwire Disco setup runs the injectors in two banks of four so an ECU fault would lose you 4 cylinders at a time.

Some people talk about sticking valve guides, you would notice rough idling and uneven cranking speed if this was the case. I haven't actually met that one myself. Could also be a weak valve spring, letting the lifter pump up on the go.

hmm it could be dropping more, it really feels like theres all of a sudden no power, and its hard to rev.
Does the ECU turn on a set of relays per bank or does it do it directly?

Cheers NAT

I just had a look at the old spark plugs, that I pulled out last week,

MY chart says it is overheating: Possible causes are overadvanced ignition timing, air/fuel mixture too lean, water or oil level too low, plugs not fitted (tightened) correctly, plug heat range too hot.

They were BPES 4,
I have put in BPES5,

hmmm... I'll check the injector connections and see where I come up with. I am assuming the best way to clean ionjectors is to pull them out and bring to a shop?


When its running usually it pours like a kitten! heaps of power, there usually is a petrol smell as well, thats why I thought it was an igntion issue. petrol.. no spark...