Folks,
this is a bit of a pain. She's been grand all summer but now it's getting colder she's failing to start when cold. There was one time it wouldn't start and I cleared a security Serial link error and she started fine. I don't think this is related.

It started with crank, burble, nothing. Then crank burble, nothing. Then crank, fire - run (albeit lumpy to start with as cylinders chimed in)
As it gets colder it's more likely, crank, burble, nothing. Crank, burble, nothing, Crank crank crank crank nothing.

If you get lucky and it fires up, hot or warm restart is fine.

Currently looking at about 3C on the thermometer and she won't fire at all.

Faults on the nano
Multiple misfires (not surprising), and random upstream O2 no signal (occurred once, not present). I cleared then, they haven't come back but she still won't start.
Yes, plenty of fuel - both types :)

Where should I begin?

How old are your spark plugs and leads? Sounds like damp leads to me or worn out plugs. Or a coil pack also possible?

If all of the above are OK, it could also be your crank sensor dying.

What fuel pressure do you see at start up? Those Laser spark plugs lights are a quick and easy way to get comfortable on the spark, may be worth pulling some plugs to see what you can see.
Is your idle air setup looking OK?

Not sure I followed about the O2 sensors, but equally I'm not sure they do too much in the first few seconds. Have you got a heater voltage?

I just went out to see if there was RPM showing while cranking (saw on a post that claimed you should see 1-200rpm when cranking if the CPS is OK) and she started first hit. She cranked for half a second with 0rpm showing then boom - straight into perfect running. I took her for a 30 minute drive to make sure the battery is fully charged and she behaved perfectly. Then started twice more when I got home. Hmm.

Thanks for the suggestions, I'll start with plugs and wires -they're old! (I don't see them on my list, so they're probably coming up to 30k)

By coincidence, I was chasing a misfire under load on my Jeep this afternoon and thought I'd start with plugs - to find that the king lead literally just snapped at the coil end connector and fell off. It was a cheap pattern part (Blueprint) which looks like it has been arcing for a while. I was starting to look for a CPS for that one too! Hopefully new leads will sort it.

Morat

By the way: Are good old NGK BPR6ES still the recommended plug?

Also.. red HT leads? https://www.island-4x4.co.uk/ignition-lead-4046-9802-hls103xp-p-461.html
A bit tarty :/

CPS I've known to play up with temperature, but looks like you've ruled that out. I think Richard has said plugs need changing far before 30k, particularly so if its on gas. (I think, but not 100% sure its 10k they should be?). As Romanrob said those spark plug testers can help if your not sure, particularly if you think a coil pack might be the problem. If its just showing multiple rather than specific cylinders I'd suspect its not the coil pack at fault though.

Given its dark now - pop outside and lift the bonnet, and have a look while the engine is running for any signs of arcing round the plugs and leads.

Can't see anything, but my eyes are pretty knackered too!

You'd see it in the dark. Best way is to let the eye muscles relax so you aren't focussing on anything and you may see a glow around the leads. LPG does wear plugs faster than on petrol, I change mine every 10,000.

I'd be swapping the plugs then and see what happens. Wouldn't do any harm to have a spare set of leads just in case though. AFAIK thats the plug you want to use - whats in there currently?

Morat wrote:

By the way: Are good old NGK BPR6ES still the recommended plug?

IIRC, that's what I've got. Oh, plus new leads.