Misfire!!!

Got a misfire, coughs and sputters at low revs!
I went through some deep water a few days ago and it has happened since, i checked plug leads and found water sitting in cylinder 2, so cleaned all that out and sprayed the all curing WD40 down plug hole and it has made a big difference... but it still coughs at low rev's (below 2000rpm), have also noticed that when on tick over it is slowish to pick up when you rev it. Now another one is that it seems to cough and splutter after i've gone round a corner or island?. Everything is fine at higher rev's. It's the DOHC 16v engine BTW. The misfire was very bad before cleaning out water and spraying with WD40 and the engine management light came on, infact it is still on.
Idea's and pointers please.
Mart

Hi Doc,

I am not a mechanic (far from it) and am sure one of our expert grease monkeys will be on line soon to advise, but my suspicion would be water/crap in the fuel line somehow/somewhere.

Not had the issue with a Jimny but had similar issues in the past which were aggravated by cornering and/or braking and it turned out to be crap in the fuel system. Unfortunately, the fuel filter for the Jimny is in the tank. WTF was the designer smoking when he thought up that little gem?! Twat.

You may have water in one of the connectors somewhere under the bonnet.

As to the water in the fuel possibility, there is a black charcoal filter alongside the alternator.
This fills with fuel vapour when standing, and when the engine is running a valve opens and allows the engine to suck air into it through a short piece of pipe pointing down. This may have got filled with water.

You may have got water into the tank, which is a tank off job.

Needs doing sooner rather than later as it will corrode the fuel pump.

"a short piece of pipe pointing down"

Is that another example of the Jimny designers enjoying some Jamaican Woodbine?!

Add a snorkel, but then there's this dodgy piece of pipe to water into the fuel system! What were they thinking?!

Right, just been out to have a look at the charcoal filter and it seems ok as in not full of water . The short breather pipe does not stick down on mine, it is on top with a breather cap on it so i'm pretty confident that i have not sucked water in there. Does that filter serve an important function? Could it be linked out to prevent any issues?
Mart

Just leave it alone, no-one has ever reported any trouble.

How the fuel tank works:

The fuel filler cap is sealed, but has a one way valve to allow air into the tank, so it doesn't squash flat as you use the fuel.
The tank has a vent pipe with a one way pressure valve, that allows fuel vapour to come out when standing in the warm. This pipe leads to the carbon filter by the alternator.

So on a hot day when parked, there is no smell, as all the vapour goes to the carbon filter which absorbs it.

Just after you start the engine, a valve on the manifold opens, and allows the engine to suck fresh air through the carbon, purging it of any fuel vapour.

(If it were full of water, water would get into the manifold and likely cause a missfire)

If you let water get over the filler cap, and it leaks, water will get into the tank. A tiny bit will get in through the vent when running anyway. The water is heavier than petrol, and lies at the bottom to rust through the tank.
When you get enough in there, the pump starts to suck water, and the engine stops and all the fuel system goes rusty, although the filter should stop the water droplets......

You know if the filler cap leaks if it doesn't go sssssh when you undo it when the car has been standing for a few minutes after a run, or on a warm afternoon. (or more likely, the metal filler spout at the tank rusts through, but this leaks fuel when the tank is full.