Technical Engine misfire in wet weather

[macp]

My wife rang me complaining of the engine stuttering and engine warning light coming on. This was yesterday a very wet and rainy day. This also happened some weeks ago in the same sort of weather. And was diagnosed as HT leads and spark plugs. They were replaced and everything was fine with the car running better than ever until yesterday. Anyway she nursed it home and I arrived to take a look. I sprayed some dry lube all over the electrical connections I could see then started it. The car immediately sprang into life sounding as sweet as ever. I took it down the road and back and it was perfect. I don’t think for one minute that I cured it though.

Anybody have any thoughts ?

 

[koalar]

when its failing

look at it at night, somewhere dark not under a street light

you will probably see some arcing

a White sparkle is fine. Blue arching is what you are looking for.

also read the codes. If its misfire on a cylinder and you swap the coil packs over (older cars with two or 100hp) then you will have you answer. It may not be HT. Its likely to be electrical. But even this can be a red herring as water in the airbox although rare isnt unknown

look around the HT system for fine Black lines like spider webs

Also check the duck bills are clear. Plenty of threads on here.

 

[DaveMcT]

You have new plugs and leads so the only thing left is the coils. They are not expensive.

However, we don't know the car model. the 1.1 has a known problem with the engine ECU connector that mimics ignition faults.

 

[macp]

when its failing

look at it at night, somewhere dark not under a street light

you will probably see some arcing

a White sparkle is fine. Blue arching is what you are looking for.

also read the codes. If its misfire on a cylinder and you swap the coil packs over (older cars with two or 100hp) then you will have you answer. It may not be HT. Its likely to be electrical. But even this can be a red herring as water in the airbox although rare isnt unknown

look around the HT system for fine Black lines like spider webs

Also check the duck bills are clear. Plenty of threads on here.

Many thanks for your reply I will have a look around. I will also do a search on duck bills as im not familiar with that term. Although not an experienced Fiat guy I admit.

 

[macp]

You have new plugs and leads so the only thing left is the coils. They are not expensive.

However, we don't know the car model. the 1.1 has a known problem with the engine ECU connector that mimics ignition faults.

Apologies yes a small but important detail doh!!
Its a 2008 1.2 8v

 

[DaveMcT]

No worries. "Duck Bills" are the rubber drain grommets in the scuttle which stop rain water building up. They get clogged with dirt, letting water into areas where you don't want water. But TBH are unlikely to affect the ignition.

Shop 4 Parts have coil packs. They do have a minimum order value so get a few other things to get free postage.

Ignition Coil Pack 46548037

www.shop4parts.co.uk

 

[koalar]

No worries. "Duck Bills" are the rubber drain grommets in the scuttle which stop rain water building up. They get clogged with dirt, letting water into areas where you don't want water. But TBH are unlikely to affect the ignition.

Doesn't it eventually leak over the body computer

isnt things like the Crank sensor also run up here

has it been confirmed its ignition likely but things can get expensive if you keep guessing wrong, I find it better to diagnose as much as possible first. Sometime you still have to make an educated guess as a last resort.

 

[koalar]

hard to know what equipment you have.
ability to read the engine check code would help

if I had nothing except a socket set

the next time it fails I would take the air box / filter off and unplug the injector cable for cylinder one and start the car. Make a note of if its worse or the same. Stop the car and plug it back

repeat for cylinder two, three and four

if two cylinders make no difference its those that aren't firing. If they are feed by the same coil, its either that coil or its supply voltage or signal.

There's two identical coils, swap them over. If the fault swaps to the opposite two cylinders you have found the faulty part.

might need take it for a drive in the wet again to replicate the fault again

 

[jrkitching]

Next time it misbehaves and it's dark, open the bonnet with the engine running and look (don't touch!) at all the HT electrics; you might just see something sparking to earth - in which case you've found the fault.

 

[Mike1alike]

I had this kind of problem on my Punto. And apparently a lot of people did.
I fixed it by replacing the intake manifold gaskets. I bought a set (not expensive at all) and replaced them all, there is a gasket for everything that is connected to manifold.
The ones that are causing the problem are the ones between manifold and Cylinder head, 4 of them, there is one for each cylinder. Being worn, they allow some air to get inside, during admission and its only a little, so very hard to detect, the engine seems to be working fine. But, on high humidity, the air that gets inside is wet and that affects the burning therefore comes stuttering.
After I replaced the gaskets the problem was fixed.
When you take the manifold down it's possible that you'll need to take the cooling temperature sensor down as well, so some cooling antifreeze will spill. To avoid that, you can take some out, before, extract it from radiator (using a hose or so) and when you're done, top it up and do the bleeding of the cooling system.

 

[DaveMcT]

If the coil packs are new or known to be OK that's not ideal, but m my logic with OLD coil packs is that £24 for two packs just swap them out. Ideally, read the fault codes before doing anything.

Crank position sensor usually works or doesn't work, especially when it gets hot. But wiring could be faulty so check all connections.

I don't believe that blocked scuttle drains can wash water over the 1.1 ECU as water will be going down the heater intake before that happens. But I might be wrong.

 

[koalar]

I had this kind of problem on my Punto. And apparently a lot of people did.
I fixed it by replacing the intake manifold gaskets. I bought a set (not expensive at all) and replaced them all, there is a gasket for everything that is connected to manifold.
The ones that are causing the problem are the ones between manifold and Cylinder head, 4 of them, there is one for each cylinder. Being worn, they allow some air to get inside, during admission and its only a little, so very hard to detect, the engine seems to be working fine. But, on high humidity, the air that gets inside is wet and that affects the burning therefore comes stuttering.
After I replaced the gaskets the problem was fixed.
When you take the manifold down it's possible that you'll need to take the cooling temperature sensor down as well, so some cooling antifreeze will spill. To avoid that, you can take some out, before, extract it from radiator (using a hose or so) and when you're done, top it up and do the bleeding of the cooling system.

easy to test with an atomiser. Spray a little water spray around the joint

 

[Mike1alike]

Yes, and another easy way to test is this: on the day with high humidity (or sprayed water around the joint) start the engine and let it run very little time, like 1-2 mins. Then stop it and wait another 2 mins. Then try to start it again. If the manifold gaskets need to be replaced, you will have problems starting the engine in theese conditions. It won't start at first, just crank. And it will start at about the 3rd time of turning the ignition on. That's what it did at mine.

 

[Mike1alike]

And you can check this old post

Fiat Punto mk2/2b 1.2 8v (2004) - Rough idle, mostly on electric load | FIAT Punto (Mk2/2b)

Are the ECUs and body computers interchangeable between the 2 and 2b do you know? I didn`t know that. But since I cleand / replaced almost everything that could cause rough idle I`m also starting to think this might be an ECU issue. And also I start to think this is a common Punto 2b problem...

www.fiatforum.com

and see a lot of people having kind of the same problem and no fix gave any result.
I did this fix (replaced gaskets) and the engine runs really smooth since.

 

[koalar]

If the coil packs are new or known to be OK that's not ideal, but m my logic with OLD coil packs is that £24 for two packs just swap them out. Ideally, read the fault codes before doing anything.

Crank position sensor usually works or doesn't work, especially when it gets hot. But wiring could be faulty so check all connections.

I don't believe that blocked scuttle drains can wash water over the 1.1 ECU as water will be going down the heater intake before that happens. But I might be wrong.

ecu is on the battery tray ?

Blocked duck bills and water running over the back of the body computer and accelerator pedal is common. I very much doubt this is the cause but for the two or three second to look for water sitting in the scuttle area it would be the first thing I would do.

on the older Pandas with two identical coil packs you should never have to buy a coil pack without being able to diagnose the problem first. I have had one fail. That only failed very rarely on very hot days. I swapped the coil packs over and waited for it to next fail.

assuming its a HT fault and just swapping everything isnt the way I would go, although you can get lucky.

I have driven my Panda (05 1.2) through some horrendous conditions and across deep fords. I do only go through standing water at a crawl. I don't remember ever opening the bonnet and seeing any damp or mud towards the top of the engine or any stuttering on wet motorway's. I am fairly sure but not 100% that under normal conditions spray does not reach anywhere near the HT. But I could easily be wrong

 

[macp]

Thanks all it does seem so odd that it has only happened on two identical days where it was raining hard.
Otherwise the car runs like clockwork.

You do see so many vids of panda 4x4 crossing streams and splashing through fords. I’m pretty sure they don’t have anything special to stop water ingress. And they are not raised up that much more than the standard car. I don’t think

 

[koalar]

Thanks all it does seem so odd that it has only happened on two identical days where it was raining hard.
Otherwise the car runs like clockwork.

You do see so many vids of panda 4x4 crossing streams and splashing through fords. I’m pretty sure they don’t have anything special to stop water ingress. And they are not raised up that much more than the standard car. I don’t think

not so odd.

Keep an eye on if or when it next fails
we see mainly the same faults over and over again

water in the Black fuse box to the right of the battery use to be fairly common but haven't seen one in the last few years
and electrical gremlins after the duck bills were blocked

but a misfire when its raining isnt one I have come across before. (on a panda) Although twice may just be a coincidence yet.

there are electrical wires under the car that are in the spray. Crank, O2 and probably more

of cause things would be easier if we had more to go on.
a simple fault code reader for around £10 might help. A generic code like random misfire will not help at all. But injector or ignition circuit faults would

Spraying dry lube on every connector then it works doesn't help as much as spraying dry lube on (A) connector and and then it works. Even then it doesn't mean its (A) connector. Something else could have just naturally dried out and it a coincidence

individual small steps is normally the best way

 

[macp]

I actually have Carista which may or may not plug in and read the ecu.

 

[koalar]

I actually have Carista which may or may not plug in and read the ecu.

according to their site its Good to go for basic code reading but some of the other functions such as live data will not work

worth a try

 

[macp]

I could have sworn I saw an input socket on the drivers side but cant see it now ?

Ah ok its beneath the panel with two screws.