94 SL2: Heads up about ignition coils
This past March, with all the rain here in Ohio, my car began to missfire when I started it on damp mornings. It would
smooth out as soon as I got on the street headed down the road. But it got progressively worse as time went by. A short
time ago, I asked here about spark plug part numbers, then nearly had a heart attack when presented with the price at
my local Advance Auto Parts. It was nearly $27 for 4. I didn't buy them. Instead, I pulled the originals, cleaned, and
regapped them, and reinstalled them. Problem fixed. . . . . . for about a week.
Pulled them again, and noticed that 2 of them were black, and 2 were white. #2 and 3 were black, indicating a
common problem like an ignition coil.
Searched a little deeper and found that the posts on top of one of the ORIGINAL ignition coils were badly corroded
as well as the connectors inside the ignition wire boots. I cleaned and cleaned and cleaned, but could not get the
spark to be consistent. So, I swapped in a couple clean old coils from a V6 3100 car from my old parts box.
Against the recommendation above, because of price concerns, I stuck in a set of USED Bosch Platinum R2
spark plug from the same parts box. I replaced the coil ends on 2 of the spark plug wires and put it back together.
It now runs like a scalded dog. Fantastic. And it didn't cost me a single dime. Just a couple hours time in the rain.
I'm retired, and COVID did a number on finances, so money is tight. As finances allow, I'll order up the correct
plugs and wires from Rock Auto, but for now, "You gotta do what you gotta do".
Anyway, my point herein was to not forget to check the coil terminals and spark plug wire ends when you have a
missfire. And keep a good used parts bin. For instance, I've saved hundreds of dollars on disk brake rotors over the
years by turning an old set rather than replacing with new ones; especially REAR rotors. I have 2 used rear rotors
tucked away now, ready for the next time; an old starter that just needed brushes, an alternator, 3 sets of dash gauges,
multiple radios, gas cap, radiator cap, various electrical switches, and plenty of other things. PLAN AHEAD!
smooth out as soon as I got on the street headed down the road. But it got progressively worse as time went by. A short
time ago, I asked here about spark plug part numbers, then nearly had a heart attack when presented with the price at
my local Advance Auto Parts. It was nearly $27 for 4. I didn't buy them. Instead, I pulled the originals, cleaned, and
regapped them, and reinstalled them. Problem fixed. . . . . . for about a week.
Pulled them again, and noticed that 2 of them were black, and 2 were white. #2 and 3 were black, indicating a
common problem like an ignition coil.
Searched a little deeper and found that the posts on top of one of the ORIGINAL ignition coils were badly corroded
as well as the connectors inside the ignition wire boots. I cleaned and cleaned and cleaned, but could not get the
spark to be consistent. So, I swapped in a couple clean old coils from a V6 3100 car from my old parts box.
Against the recommendation above, because of price concerns, I stuck in a set of USED Bosch Platinum R2
spark plug from the same parts box. I replaced the coil ends on 2 of the spark plug wires and put it back together.
It now runs like a scalded dog. Fantastic. And it didn't cost me a single dime. Just a couple hours time in the rain.
I'm retired, and COVID did a number on finances, so money is tight. As finances allow, I'll order up the correct
plugs and wires from Rock Auto, but for now, "You gotta do what you gotta do".
Anyway, my point herein was to not forget to check the coil terminals and spark plug wire ends when you have a
missfire. And keep a good used parts bin. For instance, I've saved hundreds of dollars on disk brake rotors over the
years by turning an old set rather than replacing with new ones; especially REAR rotors. I have 2 used rear rotors
tucked away now, ready for the next time; an old starter that just needed brushes, an alternator, 3 sets of dash gauges,
multiple radios, gas cap, radiator cap, various electrical switches, and plenty of other things. PLAN AHEAD!
Last edited by PrestonIII; Jun 1, 2025 at 04:10 PM. Reason: title change
Years ago, I bought a 94 Chrysler New Yorker for a $100 bill and a used dvd player for the house. All I did to that car was clean the coil connections and put a set of plugs and wires on it. I sold it for $1,500. Corrosion is an issue that people often overlook.
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