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2002 chevy trailblazer_ls
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8 Posts
Discussion Starter #1 (Edited)
I changed my plugs a short while ago due to a very bad misfire on cylinder #6. the new AC Delco plugs fixed the rough idle and misfire....for about 3 weeks. I was sitting in a drive-thru when the miss returned. now after another 3 weeks today it finally set a CE light, I pulled the code when I got home and once again it says 2 codes. p0306 and p0306pending. I removed the coil and plug, and noticed a small amount of oil on the spark plug and rubber boot. the dielectric grease on the plug and boot has turned yellow and I noticed some rust on the terminal inside the boot on the coil. I cleaned it off with some 800 grit sand paper and then cleaned the plug and any excess oil I could find inside the sparkplug tube. I replaced everything making sure the coil was aligned, but I did notice the coil would shift side to side after is was tight.


This is a picture of the cylinder #6 plug tube before I cleaned it. 2014-05-31_18-04-49_551.jpg


Im pretty sure the issue is coming from a leaking valve cover gasket, and if so, could you let me know what all I will need to change it. (ex. valve cover gasket, silicone, new spark plug, ignition coil, dielectric grease, anti-seize intake gasket.) this is my only vehicle so I need to make sure and get everything I need in the first trip.

I started it and let it run for a few minutes. At first it was back to a smooth idle but the miss returned within a couple minutes. I did not have any dielectric grease to put inside the boot before re-installing the coil, which may be why the miss came back so fast. any help would be great.
 

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2002 chevy trailblazer_ls
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4,125 Posts
try moving that coil to a different cylinder. like 2 or 3. Then see if the misfire follows. Sounds like you have a bad coil happening. While the valve cover gasket leak is am issue I don't think its the culprit and book time is like 5 hours to change it.
 

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2008 isuzu ascender
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975 Posts
miss

Agree I would verify the coils as previous poster said before ripping into the valve cover if you don't need to , that's a big job. Picture doesn't look that bad and probably not the issue.
 

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2002 chevy trailblazer_ls
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8 Posts
Discussion Starter #4 (Edited)
"I changed my plugs a short while ago due to a very bad misfire on cylinder #6. the new AC Delco plugs fixed the rough idle and misfire....for about 3 weeks. I was sitting in a drive-thru when the miss returned. now after another 3 weeks today it finally set a CE light, I pulled the code when I got home and once again it says 2 codes. p0306 and p0306pending. I removed the coil and plug, and noticed a small amount of oil on the spark plug and rubber boot. the dielectric grease on the plug and boot has turned yellow and I noticed some rust on the terminal inside the boot on the coil. I cleaned it off with some 800 grit sand paper and then cleaned the plug and any excess oil I could find inside the sparkplug tube. I replaced everything making sure the coil was aligned, but I did notice the coil would shift side to side after is was tight"


UPDATE:

i finally got a chance to work on it again, the miss had gotten worse but still has not set a CE light. i went ahead and bought a new coil, oil, oil filter, ad air filter. the new coils sits tight in the hole and has no shift from side to side and seems like it is actually sealed. the miss diminished greatly but for only a couple days. now the miss can be felt through idle and driving speeds, but it is occasional, sometimes it runs smooth and other times it is very rough. this occurred at the same time as another issue which is in a seperate thread, and im not sure if it is part of the problem.


http://forums.trailvoy.com/showthread.php?t=131929
 

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2002 chevy trailblazer_ls
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8 Posts
Discussion Starter #5
"I changed my plugs a short while ago due to a very bad misfire on cylinder #6. the new AC Delco plugs fixed the rough idle and misfire....for about 3 weeks. I was sitting in a drive-thru when the miss returned. now after another 3 weeks today it finally set a CE light, I pulled the code when I got home and once again it says 2 codes. p0306 and p0306pending. I removed the coil and plug, and noticed a small amount of oil on the spark plug and rubber boot. the dielectric grease on the plug and boot has turned yellow and I noticed some rust on the terminal inside the boot on the coil. I cleaned it off with some 800 grit sand paper and then cleaned the plug and any excess oil I could find inside the sparkplug tube. I replaced everything making sure the coil was aligned, but I did notice the coil would shift side to side after is was tight"


UPDATE:

i finally got a chance to work on it again, the miss had gotten worse but still has not set a CE light. i went ahead and bought a new coil, oil, oil filter, ad air filter. the new coils sits tight in the #6 hole and has no shift from side to side and seems like it is actually sealed. the miss diminished greatly but for only a couple days. now the miss can be felt through idle and driving speeds, but it is occasional, sometimes it runs smooth and other times it is very rough.


http://forums.trailvoy.com/showthread.php?t=131929
The missing is steadily getting worse and more frequent. I finally got some feed back from the diagnostics with a flashing service engine soon light, and a pending p0300. there is no sign of the previous p0306 for the misfire on cylinder six.

Recent maintenance:
new acdelco 41-103 iridium plugs pregapped at .38 to .39
new delphi coil for cylinder #6
new spectra premium fuel pump assembly
new pre-converter oxygen sensor
new air filter
fully cleaned throttle body

Im not sure what to do next other than take it to a mechanic and have it hooked up to a computer. any suggestions would be appreciated.
 
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