Code P0300 after replacing almost everything

I need help and some ideas everyone.
2012 JK Unlimited Sahara
138k miles

Sorry for the long post but trying to get all the info out at once to be specific.

Purchased a JK from a friend about a year ago and have had no issues until recently. About 2 weeks ago, I was driving along fine and out of nowhere lost power, went into limp mode and CEL came on. Took it home, ran an ODB 2 on it and got P0300 (Multiple Cylinder Misfire) and P0018 (Crankshaft/Camshaft Timing Misalignment - Bank 2 Sensor 1). Did some research and looked into the forums here and long story short, over the last 2 weeks, I’ve replaced the following with zero improvement:
Oil Change
Transmission Fluid Change
Spark Plugs
Ignition Coils
Camshaft Sensor (both banks)
Crankshaft Sensor
All O2 sensors
VVT Solenoids
and ran Sea Foam through the throttle body.

When I start it up it runs fine for about 30 seconds, then the idle drops to around 750 rpm’s and it shudders. When I accelerate (in park) it’ll run fine but when I release the gas it falls to around 500rpm and shudders worse before settling back at around 750.

I’ve been told by a buddy of mine who owns a shop to maybe do the throttle body because the sensor is built into those, the only sensor I think I haven’t changed. Since it’s starting normally then dropping after a bit, I tend to think mechanically it’s ok and it’s a computer or wiring problem.
I’m out of ideas though and would love any and all feedback if anyone has seen this, fixed this, or if I’m missing something obvious. Thanks.

CraigCampbell said:

LOL I just joined and posted this just before you. https://wranglerjkforum.net/threads/code-p0300-multiple-engine-misfire-detected.30381/ I too suffer from P0300 and the dealership cant find a problem

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Yup. I’ve done everything I can think of and it’s still not improving at all. If I find a fix, I’ll let you know first.

TJ

Danarch said:

This stinks, sorry about all that. I am not sure if this will help but did you try a reset on the ECU/PCM? I am not sure if that is required or helps when all the above work has been done, but I can’t imagine it would hurt anything.

You’ve done a lot above so hate to ask, but did you check the battery, battery post/terminals to make sure they are clean? I would also check the grounds and make sure they are clean, at least the primary ground.

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Thanks for the help! I haven’t tried the reset in the ECU/PCM but I’m assuming the problem is something either temperature or electronic now just because it starts fine then has issues after about 30-45 seconds.

For the battery, yeah I’ve checked that. I’ve had to disconnect and reconnect every time I installed new sensors so they’ve gotten lots of good looks. I’ll look into a reset of the ECU, the whole ECU may need replaced.

JeepJeezy said:

Did you replace all the electronics with oem?

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Thanks. No, they’re aftermarket from a reputable online Jeep site but not OEM. I will eventually replace them all with OEM, but I was hoping to find the culprit quickly as it was my daily driver.

So if I’m understanding you and Denarch right, first reset the ECU, see if there’s any improvement, and if so, we’ve identified the problem so I can then replace all the aftermarket stuff with MOPAR parts, reset it again with MOPAR and then be good? Assuming that this turns out to be the issue, of course.

Reset the ECU, no change. The ODB 2 is recommending VVT Oil Control valves, the piece in the picture. Has anyone changed these out, and can I do it without removing the heads? I can see them when I take off the upper manifold and looks like they’ll come out but don’t want to pull it if it’s going to mess something up inside. Suggestions welcome.

Also, I see a lot of discussion about the paper spacer on the camshaft sensor and crankshaft sensor but can’t find any real food info on it it. The MOPAR part doesn’t include the spacer and there aren’t any videos or descriptions of how it is to be done. What’s the right way?

Threepointsix said:

OP, look up "JT the car guy" on YouTube. He has a lot of info on the 3.6 and repairs he's done. In fact, you can send the guy $20 and he'll consult with you.

Never hurts. Best of wishes

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Thanks, I’ll check it out!

UPDATE::

Figured out the issue with code P0300 after trying everything.

BLUF: Bent pushrod cause damage to the valve lifters, camshaft itself, and the rocker arm. That jumped the timing and was causing all the rough idle, codes, and issues.

Hope this helps for anyone else having this issue, and let’s keep posting solutions to old questions as we get answers, thanks!

CraigCampbell said:

LOL I just joined and posted this just before you. https://wranglerjkforum.net/threads/code-p0300-multiple-engine-misfire-detected.30381/ I too suffer from P0300 and the dealership cant find a problem

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Found the issue. Bent pushrod. Read the longer reply below of yours isn’t fixed yet. Cheers!