Won't run after it has been raining

[terribletaj]

Hi

Got a weird problem with my e30 316i touring with the m40b16 engine, if its been sitting overnight and its been raining, it becomes very hard to start and will misfire really bad under any amount of throttle. Sometimes it will stall as well. If it doesn't rain it will start and run completely fine. It will do this until the car has warmed up then run fine again.

I've also noticed if I can get the revs over 2000rpm by very gently applying throttle it will run fine, but trying to pull away normally it will misfire so bad it throws you through the windscreen or will stall leaving me in the middle of the road stuck until I can get it to start again.

Also the rear wiper starts going by itself and the switch has no effect on it, not sure is this is connected or not?

Any help on what to look for would be most grateful.

[chh137]

Dissy cap and rotor arm?

[terribletaj]

I did think that, gonna check them tomorrow

[Brianmoooore]

Dissy cap and rotor arm?

Certainly the first thing I'd be checking.
The rear wiper problem is likely to be caused by a sticking (self parking) microswitch, mounted inside the gearbox cover of the motor assembly. As a result of BMW's non too clever routing of the washer water through the hollow wiper spindle, when the small rubber O ring seal inside the gearbox begins to fail, washer water gets into the gearbox and causes problems.
The microswitch is a readily available standard type (V4 ??), that can be obtained from the likes of CPC or RS components.

[terribletaj]

Well I checked the distributor cap today, was very worn with lots of carbon deposits but was bone dry. Cleaned it up with some emery paper for now but will get a new cap and arm on there after christmas.

Had a look at the wiper, still keeps going by itself, but playing with switch sometimes stops it so hopefully its just the switch playing up.

[galaxiedriver]

Lift the hood (I guess you call it a bonnet) on some dark, damp night and have someone try to start the car while you watch the plug wires and distributor. I'll wager you see sparks jumping around. That will tell you what the problem(s) is/are.