distributor cap problem

[nates 87 325is]

alright so today i was driving home from work then from nowhere my car developed a very strong misfire so i pulled over and popped the hood and noticed a spark coming from the top bolt that holds my cap on jumping to some water that was on my cap (it was raining) the cap and rotor are maybe 2 months old and there doesnt look like there is a crack in it anywhere. could it be something is not grounded right? i dont see why i would have any spark to the bolt anyway.

any help would be appreciated thanks
this is my first post and first bmw:)

[Sagaris]

did you use a matching brand of cap + rotor? Did you remove the dust shield that goes behind/underneath the rotor?

My first inclination is to think that a wire is bad and that the current is arcing from the wire's boot to the screw, but if it really is coming from the screw, then that means the current that is supposed to jump across the air gap to the contact on the cap is choosing to jump to the screw which the only way I can imagine that happening is if that dust shield is missing and the current is able to jump to the aluminum timing belt cover and then to the screw which discharges to that wet spot.

I would certainly inspect the cap or try another one.

[BoxDriver86]

I had something similar happen to me. My mistake was buying a cap and rotor from Autozone. I swapped them out with the old units and the problem was fixed. It's best to get OEM parts from Blunttech or Guten Parts.

This is all speculation though since I'm not sure which parts you used.

[nates 87 325is]

ha i got my cap and rotor from autozone and yes the dust shield is in there. so i guess ill replace those again and see if that fixes it. thanks

[nates 87 325is]

so i took off my cap and rotor and found out the dust shield was in there but there is a good size piece missing from it. so now i know that was my problem but now i have another i cannot find one of these to buy. i checked ebay, bavauto,pelican parts and there is nothing could someone possably point me in the right direction?

[jlevie]

Try your dealer.

[RobertC]

so i took off my cap and rotor and found out the dust shield was in there but there is a good size piece missing from it. so now i know that was my problem but now i have another i cannot find one of these to buy. i checked ebay, bavauto,pelican parts and there is nothing could someone possably point me in the right direction?

I have a few laying around the shop. If you would like I can send you one.

Just send me $5 for shipping and I will throw one in the mail to you.

Just PM me.

C/Ya