[SimonB]

Last year I had an issue that having had some heavy rain and driving through some gravel road puddles, my Pajero developed a misfire. But it doesn't last all that long.

I had the plugs replaced as part of the last service and I hadnt had an issue since then. Granted we haven't had much rain.

Today it bucketed down and suddenly the car misfired badly, especially under load. And it was way worse than the previous occasion. Then it slowly eased up

What could be the problem? I had a very careful look and can't see any water getting anywhere near the coils (or anywhere else for that matter). What other areas like electrics could be vulnerable to water?

Note I do have a rust issue on the A pillars which will be repaired next month. I can only imagine water is dripping into something electrical, but where?

[4ePajero]

Make sure it's not your ECU.
That can be costly!

[SimonB]

Make sure it's not your ECU.
That can be costly!

And how would I know

Edit: or are you saying I must first look that there's no water around the ECU?

[Roelf_le_Roux]

You lucky fellers that live at the coast. It is possible to get a very thin layer of salty deposit on the lectrics, add moisture from the rain and you can get all sorts of issues. Years back, on a 1988 Cruiser station wagon, we did battle with mud and lots of rain and puddles to get to Sodwana. Next morning it wouldn't start. Fellow camper pointed it out to me and simply sprayed copious amounts of Q20 over everything in the engine bay. Fixed.

[4ePajero]

Make sure it's not your ECU.
That can be costly!

And how would I know

Edit: or are you saying I must first look that there's no water around the ECU?

Find the ECU.
Make sure it is dry and protected.
Spray with WD40 for protection.

[4ePikanini]

Inspect the plug/HT leads. Just the tiniest of cracks can introduce water and cause a misfire. Replacement is a good idea every 100'000km.