2020 Gladiator Sport - P0300 misfire code - Potential Cams?

[Jonz78]

Hi All,

I have been facing the P0300 misfire code now for a few months with not correctly being able to diagnose it, it does have a light tick which made me believe its the cams but wanted to keep that as last resort. Have done a lot of research and replaced plugs first then even a map sensor and nothing. Took it to do a dealer and they mentioned a new egr valve which I told them it would not be the issue because it doesnt make sense to me but changed it anyway. Took it to another friend who works as a mechanic at a jeep dealer who says bank 2 4 and 6 are misfiring. He said the cams needed to be replaced which i have researched and looks like a common issue. I have taken the valve cover off to inspect them and nothing looks like its worn enough to cause a misfire? Would love any input at this point? Should I replace cams although they dont look worn? Guess I will replace rockers and lashers while im at it but worried none of this will fix the issue. Also where is everyone buying cams from? Dealer? Better anywhere else?

See picture for reference on cams.

Thanks in advance !

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[Jonz78]

Pictures

 

[ShadowsPapa]

Why automatically jump to "it's the cams!" when it could be any number of things - coil pack, spark plug, O2 sensor and more.
I don't see a problem with those that would cause a misfire to set a code or the MIL (malfunction indicator light)

Did it make noise? Was there a loud ticking?

Replace 'em if you want - but it's a lot of work and money to be spent when you'll likely come right back with a misfire.
If it was mine, I'd try to diagnose the problem, not toss parts at it because others have had cam issues. Those cams don't look worn to me from those pictures.
The part that typically causes trouble is the high lift portion of the cam and followers - meaning that unless the misfire is only above about 2800-3000 RPM, you are running on the low lift part of the cams and not where they typically have a problem.

 

[Jonz78]

Yes I agree I have been trying to diagnose this now for a couple of months like i mentioned. First thing I did was replace the spark plugs and that did nothing. I paid the dealership to diagnoise it which cost me $400. I also thought it was the coil packs but nobody who scans it including myself comes back with that. The jeep mechanic who has the most experience so far that i trust is telling me its the cams. It misfires at low and high rpms....tick is loud enough to hear from inside the cabin.

Why automatically jump to "it's the cams!" when it could be any number of things - coil pack, spark plug, O2 sensor and more.
I don't see a problem with those that would cause a misfire to set a code or the MIL (malfunction indicator light)

Did it make noise? Was there a loud ticking?

Replace 'em if you want - but it's a lot of work and money to be spent when you'll likely come right back with a misfire.
If it was mine, I'd try to diagnose the problem, not toss parts at it because others have had cam issues. Those cams don't look worn to me from those pictures.
The part that typically causes trouble is the high lift portion of the cam and followers - meaning that unless the misfire is only above about 2800-3000 RPM, you are running on the low lift part of the cams and not where they typically have a problem.

 

[Stan H]

There are 2 of those lobes that are looking like they are starting to show wear but I specifically would like to see the high spot in the lobe. If it is grooved across it then yes but being totally honest I can only see a few of the high part of the lobes.

 

[Jonz78]

THank you for the reply Stan.

What is the best way to turn to TDC? So i can send a pic?

There are 2 of those lobes that are looking like they are starting to show wear but I specifically would like to see the high spot in the lobe. If it is grooved across it then yes but being totally honest I can only see a few of the high part of the lobes.

 

[Stan H]

THank you for the reply Stan.

What is the best way to turn to TDC? So i can send a pic?

It is difficult to determine TDC by only aligning that dimple around the crankshaft bolt and the line on the engine block. Especially if you cant see it or don't have the from cover off. Hopefully you marked the cams before taking them out so you can put them back exactly the same way .What you really need — and the service manual specifies it — is a dial indicator with an extension dropped into the # 1 cylinder through the spark plug housing.

As the cylinder raises in its bore, the dial indicator needle will rotate clockwise. As the cylinder reaches TDC, the needle will stop. Then as the cylinder lowers in its bore, the needle will rotate counter-clockwise. You want to do this a couple of times and eventually zero the dial indicator gauge at TDC (where the needle stops).

And when you look back down at the dimple and the line, they should be perfectly aligned. And during the entire repair procedure, you need to make sure you keep that dial indicator on zero, because as long as you do that, you will know cylinder #1 is at TDC. If you move the crankshaft bolt, and thus the dial indicator needle moves off zero, just rotate the crankshaft bolt until that needle on the dial indicator gauge is at zero again. That is TDC.

 

[Jonz78]

Theres marks on the camshafts that can be aligned to determine TDC im just curious what the easiest way to actually turn the engine to align. Crankshaft? Just wondering if theres an easier way.

It is difficult to determine TDC by only aligning that dimple around the crankshaft bolt and the line on the engine block. What you really need — and the service manual specifies it — is a dial indicator with an extension dropped into the # 1 cylinder through the spark plug housing.

 

[Stan H]

I like this guy does it correctly that I have seen. Watch these .

 

[Jonz78]

Thank you ! Those videos guided me right through . All done . ticking is gone but still misfiring and now throwing new codes saying it’s running too lean? Do I need to reset ? I read somewhere that you need to watch the computer ? What does that mean .

 

[ShadowsPapa]

I read somewhere that you need to watch the computer ? What does that mean .

That's a great question since the "computer" has no screen to watch.

As far as "too lean" - there wasn't a leak at the valve cover, letting oil get to the O2 sensor, was there?

If you had BOTH batteries fully disconnected - which you really should have - then everything was pretty much reset in that respect.
I know in my case, the misfire was due to the thing not having learned the CCDIFF - or cam/crank positioning and they forced it to relearn that with a command (which can be done via JSCAN or AlfaOBD) but that doesn't sound like this since mine never said it was too lean, just that there were misfires.

 

[JTGuy]

For me,, this is why when my 7 year warranty is over I'll be ready to move on.

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