About 10 days ago, I started having severe missing and lurching in my van, a 1989 Chevy with a 5.0 liter. I had been needing to call my mechanic with an issue about my SDL so while I had him on the line I picked his brain on the Chev. He asked me when was the last time I did a tuneup. It dawned on me it had probably been 20 to 30,000 miles ago.

So I put in plugs, new cables, cap and rotor, and air filter. It miraculously started running much better. I’ve never had so dramatic a change from a tuneup, but then again I used to do them more regularly.

Then last night it started displaying the same symptoms again. And me all WTF? It’s more than the missing of a single cylinder, the whole engine loses power for a second, then regains it for a moment.

It occurred to me that a few times in the last year I have left the ignition key on for a spell w/o the engine running. Years ago on some other gasser I burnt a coil out in that fashion.

I did a search for symptoms of a bad coil, and it sounds a little bit like what I have going on, these especially:

#3 – Engine Misfiring.
#4 – Vehicle Stalling.
#5 – Engine Jerking, Rough idling, Poor Power.

I’m wondering if the tuneup cleaned up enough trouble to enable the faltering coil to have a bit more life. Even when it started running much better after the tuneup, it did not seem 100%.

It has 173k, I’ve owned it for about 50,000 of those, probably still the original coil.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K