P0306 Issue...thoughts?

[sbp]

Hey all,

 

My 2012 MKZ has thrown a P0306 over the past couple of weeks.  I cleared the code and then replaced all of the plugs with factory Motorcraft plugs; set at 0.054 in gap, per Lincoln.  NGKs were formerly in there, but they looked okay.  They didn't look fouled or anything.

 

So, the car runs okay for a couple of weeks and then we got a cold snap here in Colorado and bam, the P0306 code goes off again.  I don't know if the cold had anything to do with it or not.  So, I go to Advance Auto and pickup a new Motorcraft coil pack, figuring that it was either the plugs or the coil pack.

 

It is still pretty cold here today (22*F) but I replaced the #6 cylinder coil pack.  I already cleared the code before I worked on it.  So, I start it up and it is immediately idling rough and sure enough, it throws the P0306 code again.  I made sure to push in the coil pack plug until it clicked.  One thing I will say is that the former owner pretty much broke off every one of the locking tabs (red tabs on the connectors).  <rolling my eyes>  So, I pushed all of them in the best I could and hoped they clicked into place.

 

Any thoughts on now what to look for to fix this stupid P0306 code???  I don't believe I have the firing order or the cylinder order incorrect for the 3.5L Lincoln V6 engine.  Upon my research, I have read/heard that the P0306 relates to the actual cylinder number of the engine and I have read/heard that it relates to the 6th cylinder in the firing order.  However, for the 3.5L V6, the 6th cylinder in the firing order is cylinder #6, so I'm pretty sure I have the right cylinder that I'm working on one way or another.  It is the driver's front cylinder.  1-2-3 in the back (pass side to driver side) and 4-5-6 in the front (again, pass side to driver side).

 

Only other thing I can check is to possibly see if there is some sort of broken wire and/or the connector is bad.  I don't know what else it could be.  I guess a vacuum leak, but from where?  Intake?  And if so, why is it only triggering the #6 cylinder misfire?

 

Is there any way to test the coil packs?  My luck I got a bad coil pack from Advance Auto and that is continuing my issues.

 

Any help would be truly appreciated.  I'm getting frustrated with this thing.

 

Thanks,

Mat

[bbf2530]

1 hour ago, sbp said:

Hey all,

 

My 2012 MKZ has thrown a P0306 over the past couple of weeks.  I cleared the code and then replaced all of the plugs with factory Motorcraft plugs; set at 0.054 in gap, per Lincoln.  NGKs were formerly in there, but they looked okay.  They didn't look fouled or anything.

 

So, the car runs okay for a couple of weeks and then we got a cold snap here in Colorado and bam, the P0306 code goes off again.  I don't know if the cold had anything to do with it or not.  So, I go to Advance Auto and pickup a new Motorcraft coil pack, figuring that it was either the plugs or the coil pack.

 

It is still pretty cold here today (22*F) but I replaced the #6 cylinder coil pack.  I already cleared the code before I worked on it.  So, I start it up and it is immediately idling rough and sure enough, it throws the P0306 code again.  I made sure to push in the coil pack plug until it clicked.  One thing I will say is that the former owner pretty much broke off every one of the locking tabs (red tabs on the connectors).  <rolling my eyes>  So, I pushed all of them in the best I could and hoped they clicked into place.

 

Any thoughts on now what to look for to fix this stupid P0306 code???  I don't believe I have the firing order or the cylinder order incorrect for the 3.5L Lincoln V6 engine.  Upon my research, I have read/heard that the P0306 relates to the actual cylinder number of the engine and I have read/heard that it relates to the 6th cylinder in the firing order.  However, for the 3.5L V6, the 6th cylinder in the firing order is cylinder #6, so I'm pretty sure I have the right cylinder that I'm working on one way or another.  It is the driver's front cylinder.  1-2-3 in the back (pass side to driver side) and 4-5-6 in the front (again, pass side to driver side).

 

Only other thing I can check is to possibly see if there is some sort of broken wire and/or the connector is bad.  I don't know what else it could be.  I guess a vacuum leak, but from where?  Intake?  And if so, why is it only triggering the #6 cylinder misfire?

 

Is there any way to test the coil packs?  My luck I got a bad coil pack from Advance Auto and that is continuing my issues.

 

Any help would be truly appreciated.  I'm getting frustrated with this thing.

 

Thanks,

Mat

 

Hi Mat and welcome to the Lincoln MKZ Forum. Take a look here for possibilities, and how to begin diagnosing/repairing: https://www.obd-codes.com/p0306

 

Let us know how you make out and good luck.

Edited January 21, 2023 by bbf2530

[sbp]

21 hours ago, bbf2530 said:

 

Hi Mat and welcome to the Lincoln MKZ Forum. Take a look here for possibilities, and how to begin diagnosing/repairing: https://www.obd-codes.com/p0306

 

Let us know how you make out and good luck.

 

Thank you for the welcome.  Well, at this point I'm pretty much going down the list.  LOL!

 

* Replaced the spark plugs

* Replaced the coil pack

* About to replace the intake plenum gaskets (upper intake)

* About to replace the number 6 cylinder fuel injector

 

If it doesn't fix it after doing the above (which I'm about to go out and complete today), then I don't know what the heck is wrong with it.  ?  I'll probably have to take it to a Lincoln dealer and pay a ton of money to have it checked.

 

If it's a vacuum leak somewhere, not sure where else to check for that.  Only other thing I might do (since I'll have the injectors and fuel rail(s) out) is also take the intake off and replace the lower/bottom intake gaskets.  That's about the only other thing I can think of.  ?  Let's pray one of these actually fixes it.