Getting ready to pull the plugs for my timing belt replacement and just for a routine check, measured the resistance from spark plug cap to spark plug cap on each side. The left side measured real close to 25K Ohms ( Good - 5K for each cap & 15K for the secondary coil resistance ). But the right side measured about 2.5 MegOhms ...... After I removed ( un-screwed ) both spark plug caps I tracked the problem to one of the spark plug caps. After disassembling the cap, I measured the small resistor inside and it measured almost 5K Ohms exactly , so that wasn't the problem.
BTW, I had this same problem with a cap on the left side last year. After spending some time troubleshooting last year, I came to the conclusion the problem was the spring inside the cap wasn't making a good connection at the end of the spring that is inserted first. Looking down into the cap with a flashlight, it looks like there is a nice piece of metal at the bottom of the hole that the spring should have no problem making a good electrical connection to , but apparently that's not the case. I wish I had a totally toasted cap that I could dissect to see exactly how that connection is made at the distal end of the spring.
The fix I came up with is to take a short length of some small copper braid ( I used solder wick ), folded over on itself several time and then dropping it down into the hole that the spring is inserted into. Then ram it in place with a small diameter phillips screwdriver ( like setting a bullet and wad in a muzzleloader ). I inserted two wads of copper braid this way and then re-installed the spring, resistor, and screwed in the brass fitting for the spark plug and now the cap resistance measures 5K Ohms.
This looks like a permanent fix, since the left side still measures good, after doing the same repair to one of the caps on the left side last year.
Thought I'd pass this info. on since it's an easy fix and saves about $20 for a new cap. While I was at it, I did the other right cap also - another preventative maintenance measure. That one probably would have gone "high resistance" eventually, too. So all four have now been modified using the copper braid.
BTW, I had this same problem with a cap on the left side last year. After spending some time troubleshooting last year, I came to the conclusion the problem was the spring inside the cap wasn't making a good connection at the end of the spring that is inserted first. Looking down into the cap with a flashlight, it looks like there is a nice piece of metal at the bottom of the hole that the spring should have no problem making a good electrical connection to , but apparently that's not the case. I wish I had a totally toasted cap that I could dissect to see exactly how that connection is made at the distal end of the spring.
The fix I came up with is to take a short length of some small copper braid ( I used solder wick ), folded over on itself several time and then dropping it down into the hole that the spring is inserted into. Then ram it in place with a small diameter phillips screwdriver ( like setting a bullet and wad in a muzzleloader ). I inserted two wads of copper braid this way and then re-installed the spring, resistor, and screwed in the brass fitting for the spark plug and now the cap resistance measures 5K Ohms.
This looks like a permanent fix, since the left side still measures good, after doing the same repair to one of the caps on the left side last year.
Thought I'd pass this info. on since it's an easy fix and saves about $20 for a new cap. While I was at it, I did the other right cap also - another preventative maintenance measure. That one probably would have gone "high resistance" eventually, too. So all four have now been modified using the copper braid.
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