[SOLVED] p0300 - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



Welcome Enthusiast! If you already own a Chevy TrailBlazer or GMC Envoy or perhaps thinking of purchasing such a vehicle, then you have come to the best TrailBlazer and Envoy site on the net! Rainier, Bravada, Ascender, and 9-7x owners welcome too!

You are currently viewing our site as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to search and post topics, communicate privately with other members, respond to polls, upload content, and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.
Join Today!
Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > The 02-09 "How-To" and DIY Section

The 02-09 "How-To" and DIY Section Threads on Do-It-Yourself and How-To goes here.

TrailVoy.com is the premier GMC Envoy Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools
  #1  
Old 03-24-2012, 06:33 PM
beaconbab beaconbab is offline
Junior Member
 
trailblazer Chevy TrailBlazer LS
Summit White 4.2L I6 2WD
Join Date: Mar 2012
Location: So Cal
Posts: 5
p0300

I have a 04 trailblazer and its running bad. I checked for codes and first the p0301 came on. Replaced the plug and switched coils to see if it might be the coil. And now the code reads p0300. I dont know what to do... any help?
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 03-25-2012, 03:16 AM
Donwkk Donwkk is offline
Member
 
2004 GMC Envoy SLE
Indigo Blue Metallic 4.2L I6 4X4
Join Date: Nov 2011
Location: Tenn
Posts: 122
Don't assume the computer is smarter than you - it is not - and don't let it confuse you.

The computer has no magic way of knowing which cylinder is misfiring - it looks at various sensors and makes a guess - the first time around it guessed it was #1 and now it is being a little more truthful and admitting it is not sure which one or more are the problem.

You knew enough to try changing a plug and swap coils so you obviously have some experience doing it yourself - let the computer guide you but trust your common sense and go by past experience.

When you removed that one plug what did your eyes tell you - did it look recent and healthy or old and crusty - if the latter you should replace them all with ACDelco 41-103 as a first step. The proper Delco's work - don't accept whatever brand the local auto store is pushing this week - other brands might work as well but why add another unknown.

Recheck the coils - The front and rear coils can be tricky to seat properly - putting them down into the holes less than straight can result in the plug boot spring and plug top not making a good connection.

If problem remains with new plugs and properly seated coils move on to the throttle body - do a search for throttle body cleaning and you will find many threads and how to's on how and why you may need to clean yours.

Take it step by step and you will resolve the issues.
Reply With Quote Quick reply to this message
  #3  
Old 03-25-2012, 02:25 PM
beaconbab beaconbab is offline
Junior Member
 
trailblazer Chevy TrailBlazer LS
Summit White 4.2L I6 2WD
Join Date: Mar 2012
Location: So Cal
Posts: 5
Quote:
Originally Posted by Donwkk View Post
Don't assume the computer is smarter than you - it is not - and don't let it confuse you.

The computer has no magic way of knowing which cylinder is misfiring - it looks at various sensors and makes a guess - the first time around it guessed it was #1 and now it is being a little more truthful and admitting it is not sure which one or more are the problem.

You knew enough to try changing a plug and swap coils so you obviously have some experience doing it yourself - let the computer guide you but trust your common sense and go by past experience.

When you removed that one plug what did your eyes tell you - did it look recent and healthy or old and crusty - if the latter you should replace them all with ACDelco 41-103 as a first step. The proper Delco's work - don't accept whatever brand the local auto store is pushing this week - other brands might work as well but why add another unknown.

Recheck the coils - The front and rear coils can be tricky to seat properly - putting them down into the holes less than straight can result in the plug boot spring and plug top not making a good connection.

If problem remains with new plugs and properly seated coils move on to the throttle body - do a search for throttle body cleaning and you will find many threads and how to's on how and why you may need to clean yours.

Take it step by step and you will resolve the issues.
Don,
First off Thank You Very Much for your insight!

Plugs were just changed before about a 1000 mile journey a month ago as it was idling a little rough and it cleared it right up. We used the Bosch Platinum plugs as we heard they were the best for that particular vehicle.
I noticed the vehicle low on transmission fluid and added some and it is probably a little above the full line and about that time it started missing. We then cleaned the air temperature sensor on the air cleaner hose which helped tremendously and actually replaced it with a new one and removed the Throttle Body and cleaned it.
We then bought a DTC retriever and it popped up with P0301....next was to pull the number 1 spark plug....which was a little oil fouled on the electrode tip.....and not only replaced it but also swapped the number 1 & 2 colis to see if it was the coil in hopes of P0302 coming up telling us it was the coil.
Then the number P0300 came up and threw us for a loop.......I guess with all that said would over filling the transmission have anything to do with this at all?
Thanks again for your time and knowledge as we do appreciate it along with anyone else that might be able to help us.
Have a Great Weekend!
Beaconbab
Reply With Quote Quick reply to this message
  #4  
Old 09-06-2012, 02:10 PM
I6 05 blazer I6 05 blazer is offline
Junior Member
 
2005 Chevy TrailBlazer LT
Black 4.2L I6 2WD
Join Date: Sep 2012
Location: Fresno ca
Posts: 1
P0300 check engine light was blinking on my '05 tb

P0300 FIXXED!! no scanner necessary. Ok so I went on Craigslist to find a mobile mechanic for 20$ to check my OBD CODE, Because autoparts places cannot rent out obd scanners anymore in cali by law. my car was stumbling on start up and misfiring bad to where the car kinda shook, First we Got a code of P0301 (#1 cylinder misfire) after running a minute it started showing random misfire P0300, so i changed all spark plugs with no luck. Still stumbling and rough idle and check engine light on, I swapped the #1 cylinder "direct ignition coil" with the #3 cylinder ignition coil and rechecked codes. Still showing random misfire P0300 (P0301 nor P0303 didn't show up for the party at all). So with car still running went down the line and started disconnecting each ignition coil wire and replacing it back on. if it ran worse after disconnection the wire i would know that the coil is working.... so when i got to the #3 coil and disconnected it there was "NO" change in the idle and there for i new it wasn't firing ... I didn't want to get to excited because i had 3 more to check, so i continued on, all showed signs that they were firing YAY!!! Recap: the only one that didn't make a difference in the idling of the car was the # 3 cylinder. by swapping the coils you can do the process of elimination and not even need a code reader. Aldo you can rule out whether it is fuel related or wire related. long shot but its the cheapest process of elimination. in the end i bought a $62 lifetime warranty ignition coil for the TB and 140k miles she has new plugs and runs smoother than ever.
P.S. I cleaned the carburetor prior to doing all of this as i had changed the batter literally the day this all happened, (cause i thought it was a bad battery, i think the coil was shorting out and drained the battery) I thought it was having trouble resetting the air flow sensor and i read when the computer resets (battery disconnect) that any carbon build up in the throttle body can cause it to not idle correctly. so do this before any repair in this order: Prayer 1st, Process of elimination 2nd, persistence, patience & politeness.
Reply With Quote Quick reply to this message
  #5  
Old 03-08-2013, 04:15 PM
EnvoyFam EnvoyFam is offline
Junior Member
 
2002 GMC Envoy SLT XL
Sand Beige Metallic 4.2L I6 AWD
Join Date: Sep 2010
Location: Denver, Colorado
Posts: 1
Coils Seated correctly?

I have an 02 Enovy XL with 151K on it. We recently went from low elevation living (0 - 1000 feet above sea level), to high altitude living (5000 - 12,000).

The first weekend the Enovy was in high altitude it started to throw a mis-fire code P0306. I unfortunately paid a shop to replace all the spark plugs and clean the fuel system. It still mis-fired.

I have replaced all the coils now too. I am still getting a mis-fire code P0300. The Auto tech said it could be the way the coils were set. I thought I placed them properly. How does a properly set coil look?

It felt like I lined them up right. the coil was setting with a slight gap before I used the screw to tighten them down.
Reply With Quote Quick reply to this message
  #6  
Old 04-05-2013, 08:59 PM
KNBlazer's Avatar
KNBlazer KNBlazer is offline
Senior Member
 
2004 Chevy TrailBlazer LS EXT
Steel Gray Metallic 4.2L I6 2WD
Join Date: Sep 2005
Location: San Diego, KaLee-Fo-nee-ah
Posts: 813
Quote:
Originally Posted by EnvoyFam View Post
I have an 02 Enovy XL with 151K on it. We recently went from low elevation living (0 - 1000 feet above sea level), to high altitude living (5000 - 12,000).

The first weekend the Enovy was in high altitude it started to throw a mis-fire code P0306. I unfortunately paid a shop to replace all the spark plugs and clean the fuel system. It still mis-fired.

I have replaced all the coils now too. I am still getting a mis-fire code P0300. The Auto tech said it could be the way the coils were set. I thought I placed them properly. How does a properly set coil look?

It felt like I lined them up right. the coil was setting with a slight gap before I used the screw to tighten them down.
The way I did my first spark plug swap was by using dielectric grease in the boots, I too got a misfire, so I took each of them off one at a time, and wouldn't you know it.. In one of the coils the grease was intact, seated it once more and problem was solved...
Reply With Quote Quick reply to this message
  #7  
Old 11-21-2013, 04:53 PM
Povozmojno Povozmojno is offline
Junior Member
 
qwerty qwerty qwerty
qwerty 5.3L V8 4X4
Join Date: Nov 2013
Location: Palo Alto, USA
Posts: 17
This posts is*very*informative.*Thank you!
__________________
free credit score government
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum forums, you must first register.

Please enter your desired user name, your email address and other required details in the form below.
(Only letters, numbers, dashes and underscores are permitted for user names)
The user name that you choose is permanent and can never be changed.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


» Sponsors

Advertising Info

All times are GMT -4. The time now is 12:21 AM.


Chevy TrailBlazer and GMC Envoy Enthusiasts - Copyright 2004 - 2009 All Rights Reserved.
All trademarks referenced herein are property of their respective owners.
RSS Feed