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2005 chevy trailblazer_ls
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18 Posts
Discussion Starter · #1 ·
Hi everyone. First I want to thank all of you for this helpful site; I’ve been saving so much time and money with your help. Two months ago, I got a permanent Check Engine light on, PO300 “Random Misfire” with a poor idle; after reviewed some of your posts, I cleaned my throttle body, change my Bosch Platinum 2+ spark plugs for Autolite (gaped at 0.043” with a manual gauge, no so trustable) and Seafoam the system (and water pump changed), all those jobs were made possible with your help.
After all this process, what I have right now is a smooth idle and no SES lights 50% of the time, because very often my idle comes bad and the SES light comes on (PO300) when I stop on a light (more often when AC is on) ; and after a while, everything comes fine again. Other thing I noted is very low city MPG (I’m getting something between 13 and 15).
Any ideas you may think I have to explore to gat back my TB to normal again?
:thx
 

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2005 chevy trailblazer_ls
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Discussion Starter · #3 ·
I add 1/3 seafoam bottle to a half gas tank and 1/3 trow a vaccum hose. Do you think I have to clean the inyector by another way?

:thx
 

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2003 gmc envoy_slt
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7,190 Posts
:tiphat Welcome :tiphat When you cleaned the tb did you take it off to clean both sides?
 

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2005 chevy trailblazer_ls
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Discussion Starter · #5 ·
Yes, I remove my TB and cleaned both sides until they were like new... It was very dirt !! I did that at 73K, right now I have 80K on my Trailblazer.
 

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2005 chevy trailblazer_ls
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Discussion Starter · #6 ·
Do you think it could be a vacuum leak? When I remove the vacuum hose from the brake booster to inject the Seafoam , I noted that the fit were you connect that hose is kind of loose (I can rotated it) , is it normal?
 

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2007 gmc
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159 Posts
I add 1/3 seafoam bottle to a half gas tank and 1/3 trow a vaccum hose. Do you think I have to clean the injector by another way?

:thx
Nope. I missed the Seafoamed the system line. Maybe a professional cleaning depending on how long it has been since you put cleaner in the tank last?
 

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2004 chevy trailblazer_ls
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694 Posts
Did you change out your coil packs or just the spark plugs? You may be having a coil pack starting to go bad, or need to re-grease the coil packs.
 

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2005 chevy trailblazer_ls
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Discussion Starter · #9 ·
Did you change out your coil packs or just the spark plugs? You may be having a coil pack starting to go bad, or need to re-grease the coil packs.
I just changed the spark plugs. I was thinking that if a X coil is starting to go bad, I'll get a PO30X. About the re-grease, would you please explain me the term, because I'm pretty new with it.:weird: May be that was my mistake, because when I changed my spark plugs, I cleaned the coil packs for everywhere :duh:. Do I have to grease them with something special?

Thank you
 

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2003 gmc envoy_slt
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Putting a dielectric grease inside the part of the coil that goes down over the plug, helps the boot slide on and helps seal out moisture. It also makes it easier to remove the coil next time.
 

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2005 chevy trailblazer_ls
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Discussion Starter · #11 ·
So far, so good

Last Saturday, I removed each one of my coils and stretched about 1/2"-3/4" the spring that goes inside the booths, re-grease both sides of them and since then, my SES light is off, and I getting a smooth idle...Hope it keep that way.

:thx
 

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Discussion Starter · #12 ·
So far, so good

Last Saturday, I removed each one of my coils and stretched about 1/2"-3/4" the spring that goes inside the booths, re-grease both sides of them and since then, my SES light is off, and I getting a smooth idle...Hope it keep that way.

:thx


UP DATE:...SES light comes again... any other idea I can explore?:hopeless
 
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