"New" (to me) 02' Envoy and I have a cylinder 2 misfire?!?

robbiegreene508

Original poster
Member
Jul 14, 2015
14
The Envoy has 180k (already put 2800 on it in 3 weeks of ownership) and it started getting a tiny rpm drop with NO engine lights, literally like 1-150 rpms. You could feel it more under the driver's seat than see it on the gauge, or barely a puff of exhaust if you stuck your hand behind the pipe. Originally I thought maybe I had gotten bad gas, then I started figuring a bad plug or coil check engine light came on and I got it scanned... Misfire on cylinder 2 and a right front wheel bearing. I didn't clear the codes and sure enough, they went away; but the problem didn't...

I searched and found the correct/recommended ac delco plugs. Should I just start there and try plugs, or should I do the coils too? Any recommendations for the coil packs? And I haven't even looked under the hood to see the difficulty on the job, how bad is it and what should I be prepared for?

BTW, this was a one owner Envoy, and the original owner supposedly did the plugs and coils at 100k. It has been meticulously maintained otherwise.
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
:iagree: Swapping suspected bad parts, with known good ones, is a good (meaning free) way of troubleshooting. If the code moves along with a part that you swapped, then you know what needs to get replaced. :yes:
 
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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
And putting new plugs at the same time is also a good idea. For the RPM drop, have you cleaned the throttle body and disconnect the battery for 30 minutes? That type of issue usually points to a dirty throttle body.
 

robbiegreene508

Original poster
Member
Jul 14, 2015
14
Thanks guys... Mooseman, Is said throttle body issue also capable of throwing this Cel code? I have not yet done anything to the vehicle yet, I actually just got around to installing my stereo yesterday after having the interface and harness wired up in my kitchen for over a week, lol.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
No, it shouldn't throw a code. What code are you getting? If it's a P03xx, that would be for the misfire.
 

dmyers4321

Member
Apr 1, 2015
8
Chattanooga
I'm right now working on a misfiring #4. What did I find? A puddle of water under the coil, in which the spark plug was drowning. The rubber seals of the coil packs have dried and cracked. The problem started exactly like yours, but progressed to a fully dead cylinder. Soaking up all the water, then changing the plug (since I'd already bought 6) cleared it up.
 
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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
It's actually a common problem for #4 since it is directly under the top drip edge. RockAuto does have the seals only if your coils are still good.
 

Mark20

Member
Dec 6, 2011
1,630
After just doing the plugs if you don't have to immediately touch cylinders 1 and 6 avoid them to save yourself time and grief. For #1 you have to get a cable tray out of the way and #6 is a PITA. Cylinders 2 through 5 are easy to get to for coil swapping.
 
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