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2003 chevy trailblazer_lt
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12 Posts
Discussion Starter · #1 · (Edited)
[SOLVED] inter mitten misfire at idle after tuneup, no CEL light

First off thanks everyone on here for the great information, its been immensely helpful.

My problem is as follows:

1. I did a tune up two weeks ago including Plugs (delco iridium), air filter, fuel filter, throttle body clean, and techron treatment. After this tune-up all was well but I read about it being an aluminum block and worried that I had overtightened, so I removed and reinstalled at the proper torque. During removal I found I had cracked the insulator on plug #3 and replaced the plug. Upon reassembly I have had an inter mitten misfire at idle.

*Keep in mind I have yet to see a CEL or SES light of any kind.
* I disconnected the battery for 30 min+ after each service, made no difference.

2. I removed all coil packs and plugs, visually inspected and applied di-electric grease upon reassembly. no change.

3. Repeat step 2, same result. (though I might not have a coil pack seated properly)

4. Purchased a BWD coil pack and began rotating it in through all six cylinders. no change.

SO.... My thought process is to revisit the plugs and switch in a new one through all six. I am trying to avoid giving a tech $100 to see real time data, though this may be the end result. All filters are clean, throttle body as well. This problem started immediately so I have trouble thinking it is low fuel pressure but it is still an option.

Any advice or criticism in process is welcomed.

Steve
 

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2005 gmc envoy_sle_xl
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1,029 Posts
I know the CEL light will not come on if there is a misfire and you have low fuel. not sure if this is your case. It is possible you dropped a piece of ceramic insulator down in the cylinder and messed up the valve or piston ring so it might be a good idea to get a compression test.
 

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2004 chevy trailblazer_lt_ext
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119 Posts
regardless if the CEL light came on or not, hook up a scan tool just to make sure. Sometimes if a warning is pending, the CEL won't illuminate.
 

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2003 chevy trailblazer_lt
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12 Posts
Discussion Starter · #4 · (Edited)
UPDATE on issue

I started moving spark plugs around earlier today and I think I got a defective spark plug when I got the replacement for the one I cracked. No more misfire, at least for now. I also pulled off the new coikpak and replaced with original, it did not hurt performance at all (so likely just the one plug). I have an appointment to get the engine scanned tomorrow and cleaned the coil paks better. I am hoping that thats all it was.

In response to previous replys: I checked the plug which was broken and am 99%+ sure that all ceramic was contained when i pulled the plug out. But the scantool tomorrow should clarify that.

Thank you everyone for the help. Im gonna take a drive around town once I have everything buttoned up and see if it works in stop and go with the ac on.
 
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