Hello to everyone.. Im hoping to find some help with a situation on my 2008 STS... 4.6 V8
HERE GOES.... I have an intermuttent misfire situation... when it happens it throws 2 codes... P0306 / P0356
first responce was replace coil pack !.... well lets back up little more..I stop in local parts store just as soon as it happened... had them pull codes now I already did that but I wanted to confirm my code reader read that theirs read and it did... so I suspected the fastest way was to replace coil pack... I asked the guy behind the counter can you look up what cylinder is #6 ? He couldnt find a diagram a parts store.. unreal I was thinkin....so...i searched good ole google and well my search I dont think was correct...after getting on this site I fiund out my search was wrong and I think I was dealing with the wrong cylinder.....I felt stupid for not searching longer but I was in a hurry....I changed the coil pack in the auto parts parking lot...
cleared codes started motor and off we drove thinking the problem was fixed... NOT ....After the next day same issue came back...now thinkin I bought a defective coil pack I switched the coil from what I thought was cyl # 6 to cyl # 2
Any ways no change... my thinkin was if it were a bad coil pk the problem would follow to cyl # 2...
well guys Please tell me if this is correct..
Looking at the Motor... Cyl # 1 is on the left which making Cyl # 6 on the right....????

 

So to add to my first Post.....I have now felt like an idiot working on the wrong cylinder...
i took the old coil pack I saved off of Cyl # 5. And installed it on the correct Cyl # 6 if that disgram I posted is correct....and I still have the same problem.. but I didnt mention I replaced the spark plug also on the wrong cylinder... which I do need to go back and switch out put in the old known good plug from Cyl # 5... to Cyl # 6
I will do that today... but the crazy thing here is at times while driven it ...it clears up.... runs great...light goes off...
well both lights go off I failed to mention when the check engine light comes on when it runs rough...the Traction Control Light comes on too.... ok... I read that happens and is normal with a misfire situation....

 

Guess the main question is if it not spark plug or Coil pk
then it leaves the fuel injector...so I will check that injector out.... while running pull off the harness connector to the injector see if there is any change in its running behavior...
I know I can also listen to it see if its clickin.
I have not ever heard of a fuel injector intermantent working.. guess stranger things have happened.

 

I have since swopped out Cyl #6 fuel injector with the same result.... but its been 3 days of constitant misfire without it clearing up...
. That stupid TRACTION CONTROL LIGHT. Is on before the Check Engine light comes on.
if thas any thing I have no idea...
But I would have expected someone to chime in on this thread with a simular issue.....

 

I can honestly say this forum is useless !!!

No one replies.... like no one has had issues with a missfire in a caddy..

 

Did you get this figured out? I'm having a very similar issue.

 

Same here.

 

Mine turned out to be a bad coil. Once I realized cylinder 4 was on driver's side not passenger, I swapped the 4 and 6 coils and misfire moved.