Normski

I have a small problem with my car a 1996 Sti. If it's left for a long time outside say overnight and it's been raining I get a misfire for a couple of minutes until the engine is fully warmed. Obviously something it getting wet from the rain.
It goes like this, the car starts as normal and idles normally. After two or three minutes idling normally it will start to misfire, revs dropping to 6 or 7 hundred rpm from 1000 - 1100. I usually slowly rev the engine between 1500 and 2000 rpm for a minute until it clears.
It's similar if I start up and drive off after a minute or so, it will be fine for a mile or so then it will start to misfire.
It has four newish coils (1 year old) and Iridium NGK plugs (2 years old), I swapped a different set of plugs and it does exactly the same. The bonnet vents have their covers on and I have cleaned and wrapped the two multiplugs near the battery with cling film thinking that was the problem but it made no difference. I have also taken the ignitor off and cleaned it.

Has anyone got the solution? It's not a major problem but it's getting annoying now.
Thanks.

Claaarkio

iTrader: (1)

Wait for rain at night or poor a load of water over it and have a look in the dark, you may be able to see an arc from somewhere!

Dave

Normski

Thanks but I've tried that, nothing standing out, even had a mirror so I could see down the plug recess.

Normski

Sc0oby

coolant temp sensor?

Normski

Nah, I replaced that as I was getting a fault code a few months ago.

I forgot to say in my original post that I'm not getting any CEL's or fault codes.

Playsatan

iTrader: (2)

Had the same problem on mine when I left the vent covers off as the maf got soaked. I'd start there.

Normski

Ok thanks, I'll have a look at that. My vent covers have always been on but water will still get through I suppose.
I have a HKS induction kit on my car, is it maybe that the air filter is getting wet and this is going through the MAF?

james-wrx

I have the HKS induction kit on mine and it does get wet, it will hesitate and stutter until the water goes away, sometimes throws a cel as a Maff fault as well quite normal with the HKS i think

Normski

Ahh, this could be the problem then. I'll need to see about shielding them from the rain.
Thanks.