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2003 chevy trailblazer_lt_ext
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Discussion Starter · #1 ·
So yesterday i decided to change my plugs. I went with Ac Delco 41-103. The ones that came out were not bad for 95k miles.( gap between .046-.052) I did find oil in the plug hole. I had it apart and decided to clean the throttle body. I gaped the new ones to .043.
Now for the fun part. Put it all together and no start. WTF!!!! I checked everything at least 10x. Still no start. Wiring harness, reseated the coils still no start. I came on here and read up on similar problems. I loosed all the coils where they were floating on top of the plugs and guess what. IT STARTED!!!!! Now One by one tighten #1 and start. 2 and start the truck etc...... As i was going through this ever-time it would get harder to start. At #5 and #6 it would not start. Now i checked all the springs in the coils to make sure they had contact. Reassemble and a little better but real rough and CHECK ENGINE LIGHT. WTF!!! again. Disconnected the battery 30 minutes and restart. It worked but a little rough. I was able to drive it to Auto Zone for a scan. That was a waste of time,he tells me a misfire but could not tell me which one. Leaving Auto zone seamed the miss fire went away and only occurred when slowing to a stop. I drove it a t least 30-40 miles highway and stop and go traffic. The slight mis fire occurs when slowing and starting off from a stop and when the A/C in on. The misfire is not setting off the Check Engine Light. I guessing 1 or more coils are bad so i waiting on the light to come on so i can get a real scan.
Like people say AINT BROKE DON'T FIX IT! or something like that.
I had to vent sorry for this long story. This job if went right should taken me an 1.5 hr. It turned out to be the whole day.
 

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2002 chevy trailblazer_ls
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My '02 LS has a little (tiny) hesitation when I come to a stop. Thought I might maybe want to change out my plugs (110,000 miles on it). After hearing your problems I might just want to live with the hesitaition. Like I said only a little and only once after coming to a stop.
 

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Coil issues

These coils ground out to the head via the mounting bolt. Check if the mounting points are clean. Also you can unplug one coil at a time for a few seconds to find the bad one. You might need to clear the codes once your done.



So yesterday i decided to change my plugs. I went with Ac Delco 41-103. The ones that came out were not bad for 95k miles.( gap between .046-.052) I did find oil in the plug hole. I had it apart and decided to clean the throttle body. I gaped the new ones to .043.
Now for the fun part. Put it all together and no start. WTF!!!! I checked everything at least 10x. Still no start. Wiring harness, reseated the coils still no start. I came on here and read up on similar problems. I loosed all the coils where they were floating on top of the plugs and guess what. IT STARTED!!!!! Now One by one tighten #1 and start. 2 and start the truck etc...... As i was going through this ever-time it would get harder to start. At #5 and #6 it would not start. Now i checked all the springs in the coils to make sure they had contact. Reassemble and a little better but real rough and CHECK ENGINE LIGHT. WTF!!! again. Disconnected the battery 30 minutes and restart. It worked but a little rough. I was able to drive it to Auto Zone for a scan. That was a waste of time,he tells me a misfire but could not tell me which one. Leaving Auto zone seamed the miss fire went away and only occurred when slowing to a stop. I drove it a t least 30-40 miles highway and stop and go traffic. The slight mis fire occurs when slowing and starting off from a stop and when the A/C in on. The misfire is not setting off the Check Engine Light. I guessing 1 or more coils are bad so i waiting on the light to come on so i can get a real scan.
Like people say AINT BROKE DON'T FIX IT! or something like that.
I had to vent sorry for this long story. This job if went right should taken me an 1.5 hr. It turned out to be the whole day.
 

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2002 olds bravada
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My '02 LS has a little (tiny) hesitation when I come to a stop. Thought I might maybe want to change out my plugs (110,000 miles on it). After hearing your problems I might just want to live with the hesitaition. Like I said only a little and only once after coming to a stop.
If you have factory plugs on, they should be changed. It's regular scheduled maintenance and will most likely help with the hesitation.
 

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Yes, they are the new iridium plugs that will last you another 100k miles. They run nicer than the ones that came with your truck from the factory (double platinum), and you should even notice a slight in MPGs.
 

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I was told the AC/Delco's don't need to be gapped, that they are correctly gapped from the factory. Is this true. I see that Bosch also has an Iridium plug. I guess that AC/Delco would be the closest thing to OEM parts?
 

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The iridiums do come pregapped from the factory at .43 but it never hurts to double check the gap. just be careful because iridium tips are very thin and fine and they are very easy to break.

also, i would stay away from BOSCH. I use to love them until recently, now i'm a BOSCH basher along with everyone else on this forum. I had the +2 platinum's and they had an improvement for about the first 100 miles, then went back to the way it was. a couple thousand miles, i pulled them out to find BENT tips! so I just went along with the delco iridiums. couldn't be happier.
 

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Discussion Starter · #10 ·
The iridiums do come pregapped from the factory at .43 but it never hurts to double check the gap. just be careful because iridium tips are very thin and fine and they are very easy to break.
Hey the ones i picked up were NOT so double check. I had to open them up a little.
also, i would stay away from BOSCH. I use to love them until recently, now I'm a BOSCH basher along with everyone else on this forum. I had the +2 platinum's and they had an improvement for about the first 100 miles, then went back to the way it was. a couple thousand miles, i pulled them out to find BENT tips! so I just went along with the delco iridiums. couldn't be happier.
These coils ground out to the head via the mounting bolt. Check if the mounting points are clean. Also you can unplug one coil at a time for a few seconds to find the bad one. You might need to clear the codes once your done.
I'm guessing this was my problem. Since my last post this thing is run normal. The oil in the plug holes was likely my problem. I also cleaned the mounting bolt/screw lots of white film and applied di-electric grease. This was all done on my first day. Sorry if i did not post it.
Ac Delco 41-103, are these the preferred/best plugs for our I6's?
:thumbsup:
Yes, they are the new iridium plugs that will last you another 100k miles. They run nicer than the ones that came with your truck from the factory (double platinum), and you should even notice a slight in MPGs.
:iagree: Now that my truck is back to normal I'm between 16.7 - 17.5. I due for an oil change so I'm hoping 18-19. Before the change, on long halls, it was averaging 18.
I was told the AC/Delco's don't need to be gapped, that they are correctly gapped from the factory. Is this true. I see that Bosch also has an Iridium plug. I guess that AC/Delco would be the closest thing to OEM parts?
NO they are not gapped. Please check them.
 

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I'm gonna pick ip a set of plugs on the way to work this afternoon, do I need to buy some dielectric grease as well? Was recommended that I replace fuel filter as well so I'l be doing that too. Any problems associated with that part of the project?
 

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Discussion Starter · #12 ·
Update!!!! My truck is back to normal. As i posted above the oil in the plug holes must've been causing my no starts. For anyone who reads this don't be discouraged in doing the plugs. Its a learning process.

I've done tune ups before just recently on my Mustang Bullitt, and that also had problems. With a meter discovered all the coils were within specs by a .10 or so. The primary and secondary were in specs just enough but caused the misfires. I ended replacing all eight. Which leads me to ask do we know the specs for the coils in the I6 Trailvoys?

I'm taking a trip to Florida next month with the Trailblazer and will report the MPG when i get back.

Thanks
 
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