Hi, i have a 95 sti import. This problem only happens when its rained or raining. When starting it from cold it misfires until its warmed up, it trys cutting out when i pull away.But as soon as i manage to put away and give it some revs it fine. Its also fine on cold start if it hasnt been raining and it doesnt mis fire at any other time, only after its been raining. I can even drive in the pouring rain and its not a problem. i know it sounds obvious that its water getting into the intake or electrics, but im just wondering if there was a problem with this type of impreza? its got nostrils on the bonnet and a fmic. Also my dump valve sits where the old top mount intercooler used to be. do you reckon that it may be getting wet? Also i have a hks induction kit. Ive covered it with a plasic bag before it rained and when i came back out to start it, it didnt make a difference. Your help would be appreciated.

 

Are your bonnet vents blanked off? If they aren't blanked off, water could be getting onto the MAF connections giving the ECU a wrong MAF reading. It could also be getting in through the filter, check if the filter is wet next time it rains.

 

Moist air conducts electricity far easier than dry. Maybe the lead/coil packs are shorting? You could try some ignition sealer and spray over the leads and coil packs and see how it goes. Start here as its cheap and work your way up. If you can start up from cold at night and rev and see if you can see any sparks.

 

No they are not blanked off, they are open. I did suspect this could be the problem. i will have to blank it off and give it a try. It does feel like there is water mixed with fuel and runs rough but when it goes its fine and doesnt miss a beat. I havent had the car long and only just realised it plays up when its wet

 

Thanks, i will also give it ago.

 

is it common for scoobies with bonnet vents that aren't blocked off to cause problems like this when it rains?

 

Hi i had the same prob with mine it was the vent cover missing just as the others have said, i have a mushroom filter and when i changed the sponge it was soaked, new sponge and replaced the cover and i haven't had a prob

 

I have a similar issue with my MY95. I also have an open vent on the front drivers side. Mine is a definate electrical misfire though. I've not really looked into it much as I rarely drive the car when it's wet anyhow. After a decent rain fall though, open up the bonnet and have a look to see if there is water droplets collecting around electrical connectors.

 

I've also suffered from this problem. My bonnet vents weren't blanked off and water was getting onto the air filter and maf and causing massive over fuelling.

I've blanked off the vents now and it's much better

 

thanks for your help guys, will blank it off and see what happens. ive had to move my hks slightly to allow it to fit to the new fmic, but the filter is not directly under the bonnet vent so not quite sure how its managing to get the filter wet.

 

Induction kit (cone filter) + missing blanking plate is a reciepe for problems

Never had an issue with the stock airbox with the missing blanking plate though - which rules out the connector (iirc they have rubber seals on the connector anyway)