p0306 and u0010

[Fpolanco]

After 68k miles, I got the dreaded misfire CEL. Luckily I was only 20mi into a 150 trip when the Jeep started driving rough. I got home and started reading some posts regarding the p0300 codes. The solutions are varied but seems like replacing the coil packs (and maybe spark plugs, since you're already there) seem to be the most common course of action. However, I also came across some software updates that may also have helped.

My question is this: b/c I have the misfire code AND a CANBUS code, could it be safER to say that it might be a software issue?

I don't want to go ahead and replace the coil packs and have the same issue pop up a day later if its a software issue.

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[Hootbro]

Software is either good or corrupt. What can make it act intermittent can be CAN BUS wiring issues but you would need a o-scope setup and a understanding of CAN BUS waveforms to interpret.

My advice, since it is #6 cylinder, you are going to have to take the upper intake off to get to that plug and coil. You will save yourself a lot of time just taking that drivers side valve cover off while you are there and inspect the cam lobes and VVL followers. If those are toast, no need to waste swapping coil and plugs.

 

[Fpolanco]

Appreciate the response.

Complete noob so I apologize for the question: will it be obvious if those are toast?

 

[Hootbro]

Generally it will be something like this:

https://www.jeepgladiatorforum.com/forum/threads/2021-gladiator-eating-cams.86056/#post-1390834

Most times it is the intake side. The offending cylinder cam lobes will generally be wiped more than the other cylinder lobes.

#6 cylinder is going to be drivers LH side rear cylinder.

 

[Fpolanco]

You are a gentleman and a scholar. Thank you!

I read quickly through some of the posts but it seems like bad cams aren’t necessarily associated with the ticking sound. Is that right?

 

[Hootbro]

You are a gentleman and a scholar. Thank you!

I read quickly through some of the posts but it seems like bad cams aren’t necessarily associated with the ticking sound. Is that right?

There is fuel injector tick that sometimes gets mistaken for cams and the VVL followers being worn.

If you have a tick and slowly apply throttle and increase RPM and it sounds like marbles for a brief period, it definitely CAM and valvetrain related but that is not always 100%. Like I mentioned, it would behoove you to look under the valve cover before swapping coils and plugs, to avoid putting everything back together with problem remaining and then having to go back in again to check and doing double work.

 

[Fpolanco]

There is fuel injector tick that sometimes gets mistaken for cams and the VVL followers being worn.

If you have a tick and slowly apply throttle and increase RPM and it sounds like marbles for a brief period, it definitely CAM and valvetrain related but that is not always 100%. Like I mentioned, it would behoove you to look under the valve cover before swapping coils and plugs, to avoid putting everything back together with problem remaining and then having to go back in again to check and doing double work.

Hey @Hootbro...just wanted to thank you for the help. I finally finished the ignition coils and spark plugs last week sometime, luckily before the snow and deep freeze. I still had a hell of a time battling the elements as I had to work around my wife's work schedule. But I got 'er done slowly over a week or so.

Thanks again!!!

 

[Hootbro]

Hey @Hootbro...just wanted to thank you for the help. I finally finished the ignition coils and spark plugs last week sometime, luckily before the snow and deep freeze. I still had a hell of a time battling the elements as I had to work around my wife's work schedule. But I got 'er done slowly over a week or so.

Thanks again!!!

Glad to hear.

Did you by chance take the valve cover off and inspect?

 

[Fpolanco]

Glad to hear.

Did you by chance take the valve cover off and inspect?

I did. Everything looked good. Even sent pics to a gear head buddy of mine to make sure my noob eyes knew what they were looking at.

 

[Hootbro]

For reference, what was the total vehicle miles and what brand coil and plugs did you replace them with?

Did you replace all the coils or just #6?

 

[Fpolanco]

For reference, what was the total vehicle miles and what brand coil and plugs did you replace them with?

Did you replace all the coils or just #6?

Its a 2021 Mojave with about 68k-ish. I went with the aFe coils and NGK-brand spark plugs from Rock Auto. Not sure on the quality of the plugs but its in the premium section under Rock Auto. Maybe I'm a sucker

I swapped out all the coils and spark plugs b/c I figured I had done all this work to get to this point so why not!

 

[Fpolanco]

For anyone coming across this, if you've already done the work to replace ignition coils, spark plugs, remove the valve cover, etc, do future your a favor and replace the oil filter housing while you're at it. It's literally staring at you.

Mine cracked a few weeks after replacing the coils and spark plugs. Luckily its warming up to a balmy 35 degrees this week in eastern PA.

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