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Discussion Starter #1
Today while driving my CEL came on so I got the car scanned. The scanner read P0300 Random Misfire. Lately at red lights I've noticed the feeling of a slight misfire that goes away when the RPMS go over 1000 or so. I have replaced the spark plugs with AC Delco Iridiums. I took pictures of the old spark plugs in case any of you thought they looked funny. A few months ago I had a check engine light for a bad thermostat so I was running rich. When replacing the spark plugs I noticed a tannish white paste inside the (spark plug boot???) I tried removing with a small flat head as much as I could. I also did a vacuum leak test around the manifold parts with silicone spray and the engine acted normal. I ran seafoam through the booster line as well because it was time to do so but I also wanted to see if maybe a little clean out would help the P0300 issue. I am currently waiting to see if the CEL returns during my 1 hour commute tomorrow but I was looking for some pointers and other things to look at if the issue occurs again.



Also, is anyones iPhone autoguide app closing out on them? Mine has been lately.


 

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You didn't mention cleaning of your throttle body, I would put that on the to-do list.

P300 random misfire is only valid if it is accompanied with an actual misfire count. If no misfire counts occurs on any of the cylinders during this misfire P0300 You should wait for an HO² error.
 

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Most code readers will show a bit lower a Misfire count for each cylinder. At least mine does.

By the way in my opinion those plugs did not need changing but an ounce of prevention is worth a pound of cure.

---------- Post added at 10:23 PM ---------- Previous post was at 10:20 PM ----------

The white gunk you see inside your spark plug boot is normal. Humidity mixed with white lithium boot sealer grease over time.
 

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good plugs still haha. Beware, the Ignition Control Module on that style ecotec is known to fail....ALOT. I've replaced it twice in the last year on my 04 Cavalier.
 

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Levee
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^^ this or injectors sticking. A Random/multiple misfire isn't just on one cylinder tho, that means it's mission across the whole board. I would look into cleaning those injectors first (pour a whole can of sea foam in your tank at your next fill up), then if that doesn't solve the issue, then you may have other issues. Could even be a sensor starting to go out, you just never know.
 

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Hey there Clarky215285,

I'm sorry to hear of your concern. I am not properly trained to offer technical advice but I will be glad to look into this for you. Please send a private message with your VIN, dealership name, current mileage, and full contact information if any extra assistance is needed. We look forward to hear from you!

Kristen A.
Chevrolet Customer Care
 

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Clear the code and wait to see if it comes back. Do you have a rough idle? Do you feel it missfiring? Or are you just worried because you have a code? Sometimes when the HO²s start to get old they get a bit out of range from where the PCM would like to see them and it will start to lean out and start putting out codes. If you are getting a P0300 or P0303 without a missfire count I would look more at your HO²s or MAF if you have already cleaned your throttle body.
 

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Did you already clean the throttle body, maybe I already asked this though.
 

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Discussion Starter #15
It's been a couple thousand miles. Wish I could use silicone spray to clean it.

---------- Post added at 09:29 PM ---------- Previous post was at 09:18 PM ----------

Well the light came on just a few minutes ago.
 

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Read the code and report back.
 

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Discussion Starter #17
I will go to advance auto parts tomorrow and use their scanner. What things should I look at with the scanner? I think it's abilities are limited.
 

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Levee
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Ugh I really don't want to just throw parts at it.
Sea Foam isn't a part, it's a fluid! :) $8, put that in and see if it fixes it, IF not, you still performed some preventative maintenance on your car for future use :) So it's a win win situation there. :)

---------- Post added at 11:57 PM ---------- Previous post was at 11:55 PM ----------

Just pull the codes with the scanner. That's pretty much all you can do is pull the codes, and clear them. If I had my car up and going I'd head down there with HP tuners and I'd watch your car live to see where the issues are as I can break everything down pretty much by cylinder on HP tuners.
 

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Levee
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Ouch. I've got some other stuff for that year, but a lot of other places would have the same thing.
 
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