2004 gmc envoy cylinder 6 misfire - 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 > The Lounge > Introductions

Introductions Welcome to TrailVoy.com! Tell us about yourself, your vehicle, mods, location etc. (no tech questions)

TrailVoy.com is the premier GMC Envoy Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools
  #1  
Old 01-08-2011, 07:45 AM
tulane tulane is offline
New Member
 
2004 GMC Envoy SLT
silver 4.2L I6 2WD
Join Date: Jan 2011
Location: dallas texas
Posts: 0
2004 gmc envoy cylinder 6 misfire

I took my 2004 envoy, 6 cyl, 117,000 miles in for new plugs and fuel filter. I purchased the vehicle new. I have never had any problems with this vehicle until I had the sparkplugs changed. Now it indicates a P0306 misfire at cylinder 6. The vehicle idles roughly in neutral and more roughly in drive with the brake depressed. Fuel economy has decreased 25% since the plugs were changed. The engine always starts right up and I have not noticed it missing while driving but only at idle. It also has never stalled nor hesitates. The coil packs have been switched around but still throws this code out. I see no evidence of any leakage under the vehicle or from valve cover. I took the vehicle in and the mechanics were hesitant to remove the plug from the cylinder (6) as it was abnormally tight. Finally had this done and the plug showed evidence of cross threading. They did a "tap" and replaced plug but still threw out the same code. It still shows only this code and nothing else. HELP!!!!
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 01-08-2011, 08:02 AM
foarob1 foarob1 is offline
Junior Member
 
2002 Chevy TrailBlazer LS
Midnight Blue Metallic 4.2L I6 4X4
Join Date: Mar 2008
Location: ohio
Posts: 20
you may have a injector sticking. Injectos will cause more of a miss at idle if the are sticking and a spark problem will usually be more appanent under a engine load. if you can get to that injector (not sure if you can) try puting a flathead screwdriver on it and tap it with a hammer (not to hard!!!!) to see if you can get it to start flowing if it is sticking . If not I would try running 2 good bottles of injector cleaner through it the cheveron with techron black bottles are the same as the gm stuff. Run your fuel down to less than quarter of a tank put the injector cleaner in and get on the gas to try to blow out any crud.
Reply With Quote Quick reply to this message
  #3  
Old 01-08-2011, 09:57 AM
the roadie's Avatar
the roadie the roadie is offline
No longer with us
 
2004 GMC Envoy SLT "Roadiemobile"
Extreme Offroad Pewter 4.2L I6 4X4
Join Date: Apr 2005
Posts: 26,181
Who did the work? Somebody who knows trailvoys?

The plugs MUST be Delco 41-103 iridiums. Other brands have been reported as causing problems.
Reply With Quote Quick reply to this message
  #4  
Old 01-08-2011, 05:55 PM
ghoster ghoster is offline
No longer with us
 
2011 Chevy Tahoe
Mocha Steel Metallic 5.3L V8 4X4
Join Date: Dec 2005
Location: Baltimore
Posts: 12,260
Quote:
Originally Posted by the roadie View Post
Who did the work? Somebody who knows trailvoys?

The plugs MUST be Delco 41-103 iridiums. Other brands have been reported as causing problems.
You sound like a delco salesperson.

Not that you are wrong, you are absolutely correct. Still sound like a salesman though.
Reply With Quote Quick reply to this message
  #5  
Old 01-08-2011, 08:03 PM
RayVoy's Avatar
RayVoy RayVoy is offline
TrailVoy Guru
 
2009 Chevy Avalanche LTZ
Black 5.3L V8 4X4
Join Date: Jul 2006
Location: Atlantic Canada
Posts: 6,431
If the problem appeared (and it sounds as though it did) as soon as the plugs were changed, then it IS related to that change.

If the coils were swapped and the problem stayed with @6, then it may be the plug, or it might be the primary voltage connection (the electrical connector on the coil).

It might also be the secondary (high) voltage boot not being properly seated on the plug.

Of course, the question of, do you know which plug is # 6, needs to be asked.
It is the one next to the firewall, and the hardest to get to.


And sure, it could be something else, but check the simple and obvious first.
__________________
Ray
Reply With Quote Quick reply to this message
  #6  
Old 01-08-2011, 08:55 PM
christo829's Avatar
christo829 christo829 is offline
TrailVoy Alumni
 
2004 Chevy TrailBlazer LT
Silverstone Metallic 4.2L I6 4X4
Join Date: Mar 2009
Location: Fairfax, VA
Posts: 1,298


Make sure they used the AC-Delco 41-103s..

If they cross threaded one, they may also have damaged one. If they didn't do
the re-thread properly, you may not have a good seal at that plug. If they were
having problems dealing with that #6 plug, they may have damaged the coil electrical
connector, or not put it back on properly.

And are you sure they replaced that plug, instead of just pulling it, cleaning those
threads and putting it back? Just wondering.

Good Luck!

Chris
Reply With Quote Quick reply to this message
  #7  
Old 01-18-2011, 08:19 AM
tulane tulane is offline
New Member
 
2004 GMC Envoy SLT
silver 4.2L I6 2WD
Join Date: Jan 2011
Location: dallas texas
Posts: 0
2004 envoy slt 6 cyl

they did a tap and replaced all spark plugs. They said they found spark plug 5was loose and didnt look right and replaced. The vehicle has stopped shaking in neutral and drive with the brake depressed. I drove the vehicle for a week with no problems. I put a can of seafoam in the gas tank. The ses light popped back on yesterday but no shaking. This is really frustrating.
Reply With Quote Quick reply to this message
  #8  
Old 01-19-2011, 07:32 PM
tulane tulane is offline
New Member
 
2004 GMC Envoy SLT
silver 4.2L I6 2WD
Join Date: Jan 2011
Location: dallas texas
Posts: 0
tulane/2004 gmc envoy slt 6 cyl

i posted incorrectly initially. Purchased this vehicle new and it has been problem free until recently. My speedometer went bezerk but now has reset itseelf back to normal. More recently (see other posts) I have had a misfire in cyl 6. Have changed spark plugs and fuel filter. Took to shop and they think it is a bad intake valve. Th the car does not stall but misses at idle. Gas mileage has been reduced by 25%. Discoloration in cyl 6 sparkplug.
Reply With Quote Quick reply to this message
  #9  
Old 01-19-2011, 09:02 PM
christo829's Avatar
christo829 christo829 is offline
TrailVoy Alumni
 
2004 Chevy TrailBlazer LT
Silverstone Metallic 4.2L I6 4X4
Join Date: Mar 2009
Location: Fairfax, VA
Posts: 1,298
Not sure what it is with shops and valve issues lately.

Kinda doubt it's valve related. Still think it's more directly related to the plug work
you had done. A poorly reseated coil pack on 6 could mean it isn't firing at full
strength. If you can get a picture of the plug, might be able to figure out what's
happening, though I suspect it's mainly just unburned fuel and some buildup from the
crankcase recirculation. If there's enough buildup, it could be causing the valve to not
seat cleanly, but a few fuel treatments might clean that up if that's the case.

So, you had the plugs and fuel filter done...not the coils? Do you still have a CEL?
If so, is the code still for cylinder 6, or has it gone to random misfire? Did the shop
actually fix the plug and swap coils around, or was that part of the mispost? You may
want to see if you can get a closer look in to the #6 plug well, and see if there's any
blow-by.....that plug might still not be threaded in properly, or the re-thread may be
leaking.

Really still leaning towards the problem being with that coil and the overall plug job,
which sounds like it wasn't done well. Yes, it could be a valve, but *much* more likely
to still be a problem in the plug/coil.

Leaning towards the speedo problem being a flaky stepper motor. If you ever see it
stop above zero when you shut the truck off, and then stick and jump, or never zero out
and just go up from wherever it was stuck, that's usually the stepper motor.

Cheers-

Chris
Reply With Quote Quick reply to this message
  #10  
Old 01-29-2011, 03:25 PM
Thalwandi27 Thalwandi27 is offline
Junior Member
 
2002 Chevy TrailBlazer LT
Black 4.2L I6 4X4
Join Date: Jan 2011
Location: Surrey, B.C., Canada
Posts: 10
similar miss on I6

I had a similar miss at idle. The plugs are new delco. Had the mechanic put a scanner on and it showed that #1 was missing. Swapped coils with #2 and then the miss went to #2 cylinder. Put a new coil on #2 and scanned again. #2 kept showing a miss. Any ideas.
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:
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 09:36 PM.


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