here we go again P0306 after new coil pack need help

O_Dogg · **Posted:** Wed Apr 18, 2007 11:40 pm

i bought a new coil pack after i figured it was my coil causeing the misfire when i switched it to #3 it didnt want to start at all, so i bought a new coil and replaced the #3 one which was previously on #6 and it ran fine MPG went up 3-4 and started fine couldnt feel a miss.

then it started doing the same thing not starting right up cranking for awhile after a shutdown or sitting for a bit/overnight, well today my CEL came back on and it pulled the P0306 code (misfire #6 cyl.) so now what the heck do i do?? plugs were changed not that long ago with autolite coppers. the #6 plug had some oil on the threads up near the head where the socket would fit but the tip and rest of threads were normal/clean.

i only have the powertrain certified pre-owned warrenty adn they would have to run diag. on it at $45 ro so an hour to figure out what is wrong with it.

any ideas? should i try and swap out for the stock V-power NGK's?? i want to swap out coils again swap #6 for #2 and see what it does and pull a few more plugs and look at em. a friend (mechanic) said it may be a camor crank postition sensor cause they can cause this as well.

k99jk99j · **Posted:** Thu Apr 19, 2007 9:37 am

i wouldn't throw new plugs at it till you diagnos it more. couple of causes of missfire can be injectors, valve springs, coilpacks, plugs, etc.... i would start with a good solid compression test to eliminate the valvespring. and then work up from their. mike

O_Dogg · **Posted:** Thu Apr 19, 2007 1:32 pm

ive ran a few things of injector cleaner through it before, i used lucas and sea foam cleaners ill have to see if i can get ahold of a comp. checker

O_Dogg · **Posted:** Thu Apr 19, 2007 4:35 pm

update

i did a comp check i get 150 +- 2-3lbs across the board, plugs seem ashy grey with sparkles on em, the center is bright white, these plugs have maybe 2000 miles on em. couldnt do a leak down test as the comp guage we had holds the pressure.

but there still is only oil on the #6 plug threads. i am leaning towards having the valve cover gaskets and the rings around the plug tube relpaced. unelss anyone has another idea to try????

also the CEL/MIL light went out after i did all this i didnt unhook the batt. but i took out the fuel pump fuse so i wouldnt pump fuel while cranking

AndySRT · **Posted:** Thu Apr 19, 2007 4:37 pm

pulling the fuel pump fuse will clear codes so thats probly why the code is gone.

O_Dogg · **Posted:** Thu Apr 19, 2007 4:43 pm

ahh alot easier then discon the battery ill remember that thanks

k99jk99j · **Posted:** Thu Apr 19, 2007 9:17 pm

if you have a digital multimeter their is a test for the coilpacks in the haynes manual. i don't have a haynes manual but maybe somebody here does? :?:

O_Dogg · **Posted:** Thu Apr 19, 2007 9:30 pm

thinkin it may be the injector or the computor

Jeepjeepster · **Posted:** Thu Apr 19, 2007 9:38 pm

I would try the injector first.

Glad it passed the compression test.

LiLredLibby · **Posted:** Thu Apr 19, 2007 10:34 pm

O_Dogg wrote:

update

i did a comp check i get 150 +- 2-3lbs across the board, plugs seem ashy grey with sparkles on em, the center is bright white, these plugs have maybe 2000 miles on em. couldnt do a leak down test as the comp guage we had holds the pressure.

but there still is only oil on the #6 plug threads. i am leaning towards having the valve cover gaskets and the rings around the plug tube relpaced. unelss anyone has another idea to try????

also the CEL/MIL light went out after i did all this i didnt unhook the batt. but i took out the fuel pump fuse so i wouldnt pump fuel while cranking

O_Dogg.....If your valve cover gasket,and the rubber around the tube where the plug goes in,are leaking onto the plug and wire,the spark will take the closest path to ground,causing a missfire.If you don't solve the oil leak,you may never get rid of the missfire.Also,you cannot clear codes by pulling fuses,or disconnecting batteries.The OBII system has got to be cleared with a scanner.Yes ,you can cycle the key three times to pull codes,but clearing codes are not as easy as the day of the old systems.Crank and cam sensors will usually set a "Multiple cylinder missfire code".This code has a different number,not sure right off what the code is,but it's not the one for cylinder 6 missfire only.The code you have only deals with cylinder #6.Injectors that are dirty,or not pulsing correctly,will also set a different code for a lean condition,again;not sure of the PO number,but not the same code for Cylinder #6 missfire.I know that we all think of a "Missfire" as a cylinder lacking fuel or fire,but in this case,a missfiring cylinder on the OBII system is usually lacking either primary or secondary ignition,and an injector problem shows up with a different code for a lean condition.Sorry for repeating myself,and for the long post,just trying to help.

Ron

O_Dogg · **Posted:** Thu Apr 19, 2007 10:57 pm

yeah i would prefer to change the gaskets (obviously both sides) myself to save on labor charges since i dount it would be covered under the powertrain warrenty. unless it is very difficult cause it's a $100 deductable and the gaskets are fairly cheap just need to set aside a nice day to do it all.

that was my next course of action if i couldnt find a defintative answer i think the multiple misfire code is P0300 but thats not the case.

should i go to jeep and buy the gaskets or would ones form advance auto or napa suffice??

i cannot visibly see any oil leaking from the valve cover itself but i will take a closer look in the morning with the maglite and see if there is any oil around the vavle cover or just inside the plug boot area.

would you reccomend/advise a shadetree mechanic like me to do it? or should i just take it in and tell em that is the problem.

LiLredLibby · **Posted:** Thu Apr 19, 2007 11:26 pm

O_Dogg wrote:

yeah i would prefer to change the gaskets (obviously both sides) myself to save on labor charges since i dount it would be covered under the powertrain warrenty. unless it is very difficult cause it's a $100 deductable and the gaskets are fairly cheap just need to set aside a nice day to do it all.

that was my next course of action if i couldnt find a defintative answer i think the multiple misfire code is P0300 but thats not the case.

should i go to jeep and buy the gaskets or would ones form advance auto or napa suffice??

i cannot visibly see any oil leaking from the valve cover itself but i will take a closer look in the morning with the maglite and see if there is any oil around the vavle cover or just inside the plug boot area.

would you reccomend/advise a shadetree mechanic like me to do it? or should i just take it in and tell em that is the problem.

Well,Napa sells good name brand parts,and that is who we get most of our parts from.I would recomend finding a good independent shop that emploees ASE techs,if your not going to do it yourself.If you do it yourself,do it when you have plenty of time,organize all of your bolts in groups,and make sure you put everything back as it came off.If you need reference as to where everything goes,you could take a couple of close-up pictures to help remember.And also the way you have to look at it is,even if by some slim chance this does'nt cure the missfire,you will still be doing a needed repair.
If you do indeed have oil around the base of your plugs,I'm confident this could be your cause for missfiring.Keep us posted,and I'll help with any questions I can.I don't mean to sound as if I "know it all" to anyone reading my replys,but I have been wrenching for a living for about 25 years now,and I too am still learning from others with more experience.

Ron

O_Dogg · **Posted:** Thu Apr 19, 2007 11:56 pm

i have a buddy who has his own garage he went to wyotech i think one of them big schools just cant afford the garage bill right now, but i do have a good digi cam so i can snap some pics.

appreciate the help and "trouble shooting" i am willing to try anything and so far you have helped more the the stealership.

adamkrz · **Posted:** Fri Apr 20, 2007 3:47 pm

Don't feel all alone,Had a p0300 code last month - so I replaced the plugs and just last week I got a p0300 and p0306 code,it runs great so I just reset it with my scanner,

I found a TSB #1802404 for my year KJ (04) but it's for the p0300 code only..

O_Dogg · **Posted:** Fri Apr 20, 2007 4:11 pm

i cant seem to find anyone who carries the valve cover gaskets and the plug tube gaskets, i found em for the 4 banger but not the V6

adamkrz · **Posted:** Fri Apr 20, 2007 8:31 pm

My p0306 code returned today along with the p0300 code,# 6 plug looked fine,Switched coils with #1 to see what happens.

I hope I don't have to chase these CEL's like my old mazda.

O_Dogg · **Posted:** Fri Apr 20, 2007 9:16 pm

someone mentioned a noid light to check the injector and computor would it be worth it??

LiLredLibby · **Posted:** Fri Apr 20, 2007 11:39 pm

O_Dogg wrote:

someone mentioned a noid light to check the injector and computor would it be worth it??

Probably me,You can buy a set of noid light testers from Mac Tools for about 60 to 75.00. The set will usually cover about 6 different vehicles.Just keep in mind that noid tester checks to see if the driver in the computor is turning the injector on,and with injector problems you will usually see a code for lean condition,not a missfire code.
On a reply about not finding gaskets,you may have to get them at the dealer.

Ron

O_Dogg · **Posted:** Sat Apr 21, 2007 7:46 am

yeah i figured i would try to troubleshoot everything guess ill call jeep and see about the seals then

here we go again P0306 after new coil pack need help

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