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I have a 2005 Odyssey EXL with 240,000 mi. This is the second time I am changing the spark plugs, the first time was at 125,000 and they all looked fine, just like cylinders 4 5 6 that I removed this time, shown in the attached pic. Could VCM cause the plugs in cylinders 1 2 3 to look like this? Even the threads on the plugs are different between bank 1 & 2. That's not oil on them, it's like a dry soot.

Has anyone ever seen this? Cylinder #1 center electrode insulator is almost completely eroded away! Cylinders 2 & 3 look kind of rough too, like they have been running rich. Cylinders 4 5 6 look almost perfect.

I found these while doing a valve clearance adjustment. I have been getting misfire codes for quite a while. In the beginning (app 2 yrs ago), Check engine would come on and go out by itself after a few days, and stay off for a couple months. As time passed the episodes got closer together, and for the past couple months, the light has stayed on. It did go off for one day last week but came back on the next day. I'm giving all of this background just in case it might have something to do with the fowling of cylinder 1 2 3 plugs. When I read the codes just prior to this service they were the same random misfire codes, but I also got 2 new codes; 1) Bank 1 O2 sensor1 open and 2) catalyst performance low. Sorry I forgot what the number are, they are written down at home. I don't know how long the O2 sensor has been bad (it wasn't six months ago when I last read the codes) but could that cause a 'rich' condition in that bank of cylinders, resulting these plug conditions. I will be replacing that O2 sensor with this service.

I could be wrong, but I don't believe the cause is leaking valve stem seals. Could the misfires cause this? If so, why only Cylinders 1 2 3 when the random misfires were on all the cylinders.

I have not had any performance issues, in fact it runs very strong at the high end. The only noticeable misfire was a random stumble at idle. Any help will be greatly appreciated, I don't want to put everything back together and just cross my fingers.

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With 110k on them, it might be worn and then O2 sensor was giving bad signal caused it to run rich and high temperature which melted it? Just a wild guess.
 

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I have a 2005 Odyssey EXL with 240,000 mi. This is the second time I am changing the spark plugs, the first time was at 125,000 and they all looked fine, just like cylinders 4 5 6 that I removed this time, shown in the attached pic. Could VCM cause the plugs in cylinders 1 2 3 to look like this? Even the threads on the plugs are different between bank 1 & 2. That's not oil on them, it's like a dry soot.

Has anyone ever seen this? Cylinder #1 center electrode insulator is almost completely eroded away! Cylinders 2 & 3 look kind of rough too, like they have been running rich. Cylinders 4 5 6 look almost perfect.
My money is on the VCM. I am surprised that you haven't disabled yours already ($100). This time you may only need a a set a plug, but next time you may need a new set of ring. Muzzle it and drive on.
 

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VCM will absolutely cause the plugs to look like that. VCMTunerII is the solution. Let's hope you don't need rings as mentioned above.
 

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Discussion Starter #5
Thanks for all the feedback! VCM Tuner is on the way, I'll post a follow-up in a couple days after I get everything buttoned up.
 

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Discussion Starter #6
After adjusting the valve clearance, new spark plugs, and VCM tuner, my 2005 Odyssey with 240,000 miles runs perfect. It idles so smooth I can barely feel it. And no annoying vibration at highway or in-town cruising speeds. Plenty of bottom and top end power, as much as when it was new, more responsive and pulls harder than my 2017 Pilot 9 speed! Thanks for everyone's input!😃
 
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thscott
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