P0306 Code

by Silverstang Thu Jan 16, 2014 9:34 am

So I am driving home from the gym Monday and the check engine light comes on. I check the code and its a p0306 (cylinder 6 misfire). I checked the wire and boot to make sure nothing came apart. The plugs dont have 10k miles on them so I don't think thats it. The car is running fine but I do hear a slight clicking sound that I dont think was there before. I did some checking and this code can be caused by any number of issues from a bad plug to low compression.

Wanted to see if anyone else has had this issue and what did you do to fix....

by Guest Thu Jan 16, 2014 11:39 am

I am lame but maybe reboot the computer via the battery connector R&R and then run your car like you normally do. If the code reappears then you may have a problem that will need to be dealt with. Maybe it was just a glemlin as that happens sometimes like running different fuel brands or the air being to lean any number of things can cause the computer to fault a code.

by Silverstang Thu Jan 16, 2014 1:56 pm

I have a Xcal so I was able to clear the code but it came back the next day. the next step was going to be the battery to see if reseting the computer would solve the problem.

by Great White Thu Jan 16, 2014 4:56 pm

I would recommend checking the plug. also could be a bad COP (Coil on plug)

the symptoms are similar to an engine miss

by Guest Thu Jan 16, 2014 6:49 pm

I had a coil pack go out on my truck and so I was getting a miss even with the new coil pack and so I just R&R the plugs and that miss went away. I didn't see anything that grabbed me on the plugs and it is nice the miss is gone. So maybe it will be a similar fix and not overly expensive.

by **Big-B** Fri Jan 17, 2014 6:56 pm

Great White wrote:I would recommend checking the plug. also could be a bad COP (Coil on plug)

the symptoms are similar to an engine miss

This^^^^^ Also look around for any white/ashy colored traces of carbon track. You can also swap one of the coils w/ and adjacent cylinder and see if the code changes to that cylinder. That will help you rule out whether it's a plug or coil.

by Silverstang Fri Jan 17, 2014 8:48 pm

Thanks for the info. I'll take a look at them tomorrow.

by Silverstang Mon Jan 20, 2014 12:23 pm

James and B. get the prize. It appears the #6 COP is going bad. I guess the good news is these things dont just crap out on you they slowly go bad. Swaped them around and got the same results. I also tested all of them on a multi meter and the #6 read 1.0-.09 all the others were 1.9-1.6. Thought it would be a good idea to replace them all so I ordered a new set today.

Thanks again for the info.

by d_word Sat Feb 15, 2014 9:47 am

Hey Sean, funny thing I got a P0308 and P0316 yesterday. Gonna try some of the recommended stuff above to see if I can resolve it.

by d_word Sat Feb 15, 2014 3:18 pm

So i Pulled the coil on #8 and found this fluid in the spark plug well. Doesnt smell sweet like antifreeze. It was kinda like a greenish/brownish clear color. I checked my oil also, looked normal. Am I screwed? This doesnt look good.....

by **Big-B** Sat Feb 15, 2014 4:02 pm

You need to find out why there's coolant in the well. More then likely you have a head/gasket issue. Do some research, looks like they are prone to this.

by Silverstang Tue Feb 18, 2014 8:41 am

Hopefully its a simple fix. But do some research, I am sure someone else out there has had the same problem. Good luck!

by Great White Tue Feb 18, 2014 10:46 am

Silverstang wrote:James and B. get the prize. It appears the #6 COP is going bad. I guess the good news is these things dont just crap out on you they slowly go bad. Swaped them around and got the same results. I also tested all of them on a multi meter and the #6 read 1.0-.09 all the others were 1.9-1.6. Thought it would be a good idea to replace them all so I ordered a new set today.

Thanks again for the info.

by d_word Tue Feb 18, 2014 11:31 am

Hope so too. I saw alot of issues with older stangs on some forums but not much for the 05-09. Looks like maybe a cracked intake or a bad intake gasket. May have to pull the manifold and put new gaskets on. I cleaned up all the fluid and cleaned the well out. Plug and COP boot cleaned also, added more dielectric grease. Ran it for a little while, its not missing anymore, runs like normal. Gonna order new COP's while im at. Either way sounds like a fun little project this weekend or the next :/

As far as the intake manifold, I have the ford manual for removal/install seems pretty straight forward. Will keep you guys updated. Thanks for the tips.

by Silverstang Tue Feb 18, 2014 2:51 pm

hey one more thing, (I saw this on one of the forums) Check to make sure all of your plugs are torqued properly. One can back out and this will cause a misfire code as well. A guy out in the midwest was having the same problem as I was and we started sharing notes. His problem ended up being the #6 plug had backed out just enough to cause an occasional misfire. Torqued the plug back and problem solved.

by Guest Tue Feb 18, 2014 4:03 pm

Dumb question: Could that water or fluid have been from washing the motor off? I mean I would have thunk that the heat from normal operating temps allowed any fluids to have dried up? Just wondering what the experts may think?

by d_word Tue Feb 18, 2014 4:23 pm

Silverstang wrote:hey one more thing, (I saw this on one of the forums) Check to make sure all of your plugs are torqued properly. One can back out and this will cause a misfire code as well. A guy out in the midwest was having the same problem as I was and we started sharing notes. His problem ended up being the #6 plug had backed out just enough to cause an occasional misfire. Torqued the plug back and problem solved.

Ok I will check that also. Where did you order your COP's from? Saw a few on Ebay but looked like some knockoffs

by d_word Tue Feb 18, 2014 4:42 pm

6-71 wrote:Dumb question: Could that water or fluid have been from washing the motor off? I mean I would have thunk that the heat from normal operating temps allowed any fluids to have dried up? Just wondering what the experts may think?

Not a dumb question at all. I was thinking along the same lines at first. Sad thing is I haven't cleaned my engine in years lol. But I also thought it could have been some rain or snow that melted because we did have a few heavy rain/snow storm pass thru the area lately and I saw some near my CAI. We can rule that out tho, the top of the COP was bone dry and there are little moisture droplets on the boot that is not exposed. I was looking in each spark plug well and noticed tiny holes, pretty sure its engine design. The side of that tiny hole is exactly where the moisture shows on the boot so my guess is something's forcing it out.

by Silverstang Wed Feb 19, 2014 9:36 am

d_word wrote:
Silverstang wrote:hey one more thing, (I saw this on one of the forums) Check to make sure all of your plugs are torqued properly. One can back out and this will cause a misfire code as well. A guy out in the midwest was having the same problem as I was and we started sharing notes. His problem ended up being the #6 plug had backed out just enough to cause an occasional misfire. Torqued the plug back and problem solved.

Ok I will check that also. Where did you order your COP's from? Saw a few on Ebay but looked like some knockoffs

many of the ones on ebay seemed to be knock off to me as well. I used amazon, and ordered Ford parts. They were a little more than what I saw on ebay but I feel comfortable I got an oem part.

by Guest Wed Feb 19, 2014 10:29 am

I asked this question as I had a 95 Probe with the 2.0 liter and so the plugs were on top of the valve covers and water would collect if I cleaned the engine and so I learned to vacuum each hole out and this eliminated moisture collection.

Sorry to hear you are having issues to this magnitude as I've heard that 4.6's are funny and may be expensive to work on depending on requirements. Hopefully you'll figure out the specifics and can nip it in the bud the first time.

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