Replaced my distributor...

[Great A'Tuin]

My Astro had the issue w/ the engine running poorly and missing under load intermittently almost since I bought it. I changed the cap/rotor/plugs and it would ran better for a while...
It started doing again recently, always getting worse when the weather is damp. I read elsewhere out on the interwebs that replacing the distributor might be a good solution for this same problem.

I looks at replacement units and found what I wanted on fleabay for 69.99, shipping included.

I dropped it in last night in less than an hour, in fact, it only took about 10 minutes longer than to just replace the cap and rotor. And both the cap and rotor were included. It would have cost me nearly that much just for those two parts.

I test drove it around town today and it's pretty humid out has we have a bit of an inversion going on in the valley.
Astro ran perfect, every shift was solid and it accelerates smartly again. Looks like mileage is back up too.

The old cap and rotor were completely carboned up and corroded. What causes that after only 10,000 or so miles?

[MountainManJoe]

Do you have an A/C line above your distributor? For some people, water would condense on it and then drip down on the distributor. Other people would have ventilation problems inside the distributor, due to clogged screens, causing moisture to get trapped. Also, in aftermarket distributors the conductive bands are routed too close to the plug wire towers. This results in arcing and some plugs loosing spark, and others getting two.

[Rileysowner]

I will second the aftermarket distributor cap and rotor as a likely cause of rapid deterioration. The first cap, plug, rotor job I did on my van used an aftermarket one. Later I read on this board that they will last a year at best. Sure enough in a year I started having rough running and starting issues. Replaced them with OEM and all was well. The next time I did a cap and rotor with an aftermarket because I was away from home and there was no other alternative at that point, it only lasted 1.5 years and was carboned up and looking really rough. For cap and rotor stick with OEM or you will be back in there replacing them in a year or less in general.

In short my experience is they work fine at first, but wear very quickly.