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PO300 code

10760 Views 11 Replies 4 Participants Last post by  andresmontalvom, 
A
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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J
Have you cleaned your injectors?

http://www.obd-codes.com/p0300
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A
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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WOOLUF1952
:tiphat Welcome :tiphat When you cleaned the tb did you take it off to clean both sides?
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A
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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A
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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J
andresmontalvom said:
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
Click to expand...
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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CoyoteFireGuy
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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A
CoyoteFireGuy said:
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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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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WOOLUF1952
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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A
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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A
andresmontalvom said:
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
Click to expand...


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