I have a usually reliable 89 Caprice (w/ 305) that has recently developed a weird problem. It starts fine, runs well for a few minutes, then starts missing if you try to accelerate or pull up a steep driveway. You have to pull away from a light very carefully, or it dies. I haven't tested the pickup coil for proper continuity, but I have tested the ignition coil, as much as I can with a simple multimeter. If it sits for an hour or two and cools off, it starts and runs fine again for a while. Ignition module, maybe?
I'd be grateful for any good thoughts, possibilities, etc.
It is almost impossible to make any defintive tests on an ignition coil using a multimeter, especially since your problem seems to be heat related. A coil is made up of several hundred feet of fine wire, and has really very little resistance. And unless you have a very good digital multi meter you would not be able to detect any difference in resistance since a short could make a difference of only 1 or 2 tenths of an ohm. An open would, of course, read infinite resistance. And with it being heat related, the coil could have cooled off by the time you read it, thus eliminating a heat related short or open. I say heat related because the car seems to act up once it warms up. The best way to test is to determine if you are getting the correct voltage to the coil, and the correct signal at the right time. However, coils do go out, and what you have described is indicative of a coil going bad, or possibly a clogged fuel filter or bad fuel pump.
-- Dick #1349 Damn it . . . Don't you dare ask God to help me. To her housekeeper, who had begun to pray aloud. ~~ Joan Crawford, actress, d. May 10, 1977 Home Page: dickcr.iwarp.com email: snipped-for-privacy@comcast.net
Hey, thanks for the info. The ignition coil was my first thought, too. I once had a '55 Studebaker President that developed a similar problem, cured by a coil change. But I went down to get a new one at the NAPA store and the guy behind the counter started to sell me one. Then I let on that I'd driven the car down there, and he told me that if I could drive it, it most likely wasn't the coil-- that it was either good or bad. I decided that if he didn't want to take my thirty bucks, maybe I should listen to him. My multimeter isn't all that good-- a top-end Radio Shack digital, but there's more bounce in the reading than you describe. Given my woeful level of ignorance, maybe I should just replace the coil and hope for the best.
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