Misfire after heavy rain

lightning · Jun 16, 2017

Driving on the motorway in my Defender TD5 we encountered a rain storm, which after a while caused a bit of a misfire in the engine.
l kept going, the rain stopped and the misfire cleared.
What could cause the engine to misfire. Too much water in the air intake? I thought Defenders were supposed to be good in water!
Although it was the worst rain l've experienced while driving.

lightning · Jun 17, 2017

Nobody got any ideas?
I was wondering whether to fit weather seals to the bonnet sides where it sits above the wings.
As water gathers on the wings and pours in to the engine bay in heavy rain .

sierrafery · Jun 17, 2017

could have been water ingress to the crank sensor too

Colthebrummie · Jun 18, 2017

It's a bit s**t if you can't take a defender out in the rain. Should have bought a Lada.

Col

raywin · Jun 18, 2017

sierrafery said:
could have been water ingress to the crank sensor too

That sounds like a good starting point the plug on mine was old and the wires were actually bare for a couple of mm, maybe water on them would give a problem.
Have you looked order the drivers seat where the ECU sits? Mine was filling up with water and it drove me mad trying to stop it.

gazman · Jun 18, 2017

mine was caused by the throttle map switch contacts on the transfer box. When wet it must have been opening and closing and switching between maps.
It took me 2yrs to find it! I tried turning the snorkel head, sealing wires all over the landy and protecting them. It always happened when in spray from hgvs on the motorway or very heavy rain on the motorway.
It would either miss fire or after backing off the throttle would be very hessitant when putting my foot back on the throttle

lightning · Jun 18, 2017

Interesting. I will have a look at that.
l now have poor performance at under 2,000 rpm. I disconnected the MAF unit and it's better.
lt's a OE Siemens one fitted only 12,000 miles ago.

lightning · Jun 19, 2017

I took the air filter out today while replacing the MAF unit and found this.
There were bits of the filter on the mesh screen in the MAF as well.
How could this happen? I am guessing water got into the air intake, but would heavy rain cause it.

bankz5152 · Jun 19, 2017

Jesus!!! Looks like its been drowned!

How can that happen!

Im wondering if the valve is still there at the bottom of the ait intake pipe near the wing.

Though id be tempted to remove the entire air intake system, seal it all up with silicone right to the wing.

lightning · Jun 19, 2017

What valve in the bottom of the air intake?

sierrafery · Jun 19, 2017

nr 21: http://www.allbrit.de/UNI.cfm?SPRACHE=EN&PAGE=759190 , it's a simple rubber bit which is there to dump moisture but not let water in

bankz5152 · Jun 19, 2017

I was on about number 9, as its lower down, more likely to bring in water

lightning · Jun 19, 2017

Thanks.
l've had a look just now and that valve seems to be working fine.
l separated the trunking between the valve and the air filter housing, poured in some water and it came straight out of the valve on to the floor.
l looked underneath and the rubber valve is in place.
The rest of the air intake trunking looks to be OK.
l've fitted a new air filter, obviously, and a new VDO MAF unit.
lt's running better but does not feel quite as lively under 2,000 rpm as it was. (It's got a remap)
I will disconnect the ECU overnight, not sure it it will reset anything but it did used to work on my Transit Connect.

lightning · Jun 20, 2017

Still need to find out how the air filter ended up in that state.

Wimblowdriver · Jun 20, 2017

At a guess, the bond between the paper element and the soft rubber is / was faulty and just failed under pressure. Was the filter soggy wet after the rain, or is it just coincidence that it popped when it was raining?

bankz5152 · Jun 20, 2017

That is possible too. Hopefully it doesn't happen again! If it does fit a snorkel haha

lightning · Jun 20, 2017

The filter was dry, but it happened last week and l only found it yesterday.

It's a bit wierd to say the least. All l can say is that the engine misfired during a rainstorm while l was at 65 mph on the motorway.

Maybe l should have slowed down. But the motorway was almost empty and actual visibility was fine.

ozzyboydeano · Jun 20, 2017

heavy rain would not cause that .if you don't have a snorkel fitted you could be pulling in to much from the wheel arch area ie splash from the wheels

I did have a similer issue with mine but not water . I don't do water crossings but I still fitted a snorkel reason being is my air filter would choke with sand after a day of 4wding I figured the wheel arch isn't the best for air intake

neilly · Jun 20, 2017

ozzyboydeano said:
heavy rain would not cause that .

In the UK, heavy rain causes puddles to appear........or in extreme circumstances, what we call standing water.................

Cheers

ozzyboydeano · Jun 20, 2017

neilly said:
In the UK, heavy rain causes puddles to appear........or in extreme circumstances, what we call standing water.................

Cheers

do you think it doesn't rain in Australia

Misfire after heavy rain

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