Misfire code after rocker replacement

BT1974

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Dec 29, 2022
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Las Vegas, NV
I know this topic had been all but beat to death, but I have read every single post on the topic and still can't find an answer.

A couple of months ago I noticed a tapping sound coming from the engine. I used these forums and unfortunately found out I needed to have the rockers replaced. I had that done about a month ago and had the lifters replaced while they were in there. When I got it back I had a strong smell of gasoline in the cabin and the P0302 misfire code. I took it back to the mechanic who told me that they spilled some fuel on the firewall insulation which was causing the smell. They changed the spark plug for the #2 cylinder along with the ignition coil. This didn't solve either the smell or the CEL code, but the jeep is running fine. The mechanic told me they checked the compression and it is fine.

So here is where I am. The engine sounds great. I have not had it go into limp mode, which would happen every time I drove on the freeway before I had the rockers and lifters replaced. My gas mileage is up and continues to rise. The check engine light stays on all the time, but only every now and then will it give me a P0302 misfire code. When the P0302 code is not displayed, the CEL is still on but no code is stored. The gas smell persists and is most noticeable in the morning when it is cold (Vegas cold. Not actual cold.) and seems to come through the climate control system. It will dissipate as I drive.

A couple of things to note. A lot of the hoses in the engine compartment have become brittle. The windshield washer hoses and connections literally crumbled in my hand. This leads me to believe other hoses in the engine have gone bad, such as the EVAP system hoses. I have ordered a replacement, but Mopar doesn't seem to be in a rush to get it to me.

Does anyone have any ideas? It is tough for me to leave my jeep at the mechanic for extended periods of time.

Thanks in advance!
 

Dirty Dog

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I don't think the CEL should illuminate without a code. Because throwing codes IS the reason the CEL comes on. How are you reading it? If you're reading it with the key trick, that won't show all codes. You need to use an actual scanner. JScan with a supported dongle (I use the iCar Pro) seems to be the most popular option for JK owners. Walmart sells the dongle for about $30. A single VIN JScan license is about $20.
 
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BT1974

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Dec 29, 2022
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Las Vegas, NV
I have the Carobotor dash which has an interface for OBDII codes. When I get the P0302 code on startup it will be listed on the dash interface. But if I do not get the P0302 code on startup there is no code stored in the dash interface. I have also used the code reader at an auto parts store and got the P0302 code.

I can't stress this enough, it is running much better now that the rockers and lifters have been replaced. This, combined with my increase in gas mileage and the smell of gas in the cabin coming through the vents (I won't notice it until I turn on the climate control) leads me to believe it is a vapor leak in the engine compartment.
 
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BT1974

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Dec 29, 2022
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Las Vegas, NV
Just an update to this. Still have the same issues. I ordered a replacement evap line from Quadratec, but that was a month ago and they still haven't shipped it.

I have noticed that I get the gas smell right after a cold start, and I mean overnight cold. not an after work start, but it dissipates fairly quickly. The other day I started it to let it warm up while I did a couple of things. I noticed a spot on the ground and after moving the jeep I found out it was fuel. I drove to work and parked it, nothing leaking. Started it up after work and nothing was leaking.

I did the same thing this morning and saw fuel actually dripping down. But again, once the engine warms up a little bit it stops. And stops for the rest of the day. My suspicion is that I have a leak in a vapor line and the fuel condenses overnight and leaks out when the engine is started. Or could it be that the gasket on the fuel line is bad and leaks until it warms up and softens a bit.

As before, the engine is running strong and my fuel mileage continues to increase.

This is driving me crazy and is holding up registering my jeep because I can't get a smog check.
 

BigAL07

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May 18, 2021
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295
Location
Daniels WV
Have u checked your evap purge valve under the hood? They are bad for sticking open or closed and leaking at the connections. Usually would give u an evap code. Just a thought🍺🍺
 
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