Hesitation and rough idle help

T

Torque710

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Sep 7, 2025
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Hello, I was an old member here. I am trying to get my jeep back and running after sitting for a few years.

I have a 2006 base wrangler SE with the 4.0 and 43rle. About 95k miles on the odo.

My problems started with emissions cel a few years back. I unfortunately can't remember the code but something with the oxygen sensors. Jeep did some fix or recall on the wires but still had issues.

The cat clogged, got new cat and o2 sensors from NTK.

Was still getting codes for emissions and o2 with the engine running rough. Changed the gas cap and all CEL gone now for about a year.

Now the CELs are gone im left with the engine hesitating and a rough idle only during long trips.

This does not happen during startup or driving around town but on long drives the hesitation starts sometimes on the freeway and rough idle when getting off the freeway and not always.

Was looking into the possibility that its time for sparks plugs and coils when I learned about the PCV valve.

The area where the pcv elbows are is extremely greasy.

I am just trying to get confirmation that this could be creating the hesitation issue and needs to be changed out, next steps I should take, or if I should be concerned with the amount of oil that has leaked from this area?

I will add pictures of the engine in AM

Thanks
 
Ha! Well the coils are probably original but the plugs were at least done at 60-75k on the odo but I get you.

Plugs, coils and the pcv refresh

20250907_093300.jpg


20250907_093242.jpg
 
I would really appreciate any further guidance before I start throwing parts at my jeep.

I did the pcv/ccv refresh, cleaned my throttle body and connectors. I used maf cleaner to clean the throttle body and did not remove the sensors. I used electrical cleaner on the contacts. I then made the mistake of jamming dielectric grease on the connections contacts. Turned on the jeep and ended up with code p2302 and 300 (I believe) it was a misfire code. While I was cleaning up a sprayed with low pressure on the valve cover to clean off the pcv valve area before starting everything. I didnt soak it down just a quick spash of water on top after cleaned with diesel.

Well today I took apart all the connectors I put dielectric grease in and used electrical cleaner to get the gunk out. Let it all dry had the neg unplugged and I am getting p2302 with what seems like a misfire but no code.

Before I order the coils and spark plugs I am just making sure maybe its not something else. Money is super tight right now and I am a little unsure as this is a new issue after cleaning. I am newer to working on my jeep and cars in general. Really appreciate any help, thanks.

I also clean the battery contacts and didn't use dielectric grease
 
Last edited:
Torque710 said:
I would really appreciate any further guidance before I start throwing parts at my jeep.

I did the pcv/ccv refresh, cleaned my throttle body and connectors. I used maf cleaner to clean the throttle body and did not remove the sensors. I used electrical cleaner on the contacts. I then made the mistake of jamming dielectric grease on the connections contacts. Turned on the jeep and ended up with code p2302 and 300 (I believe) it was a misfire code. While I was cleaning up a sprayed with low pressure on the valve cover to clean off the pcv valve area before starting everything. I didnt soak it down just a quick spash of water on top after cleaned with diesel.

Well today I took apart all the connectors I put dielectric grease in and used electrical cleaner to get the gunk out. Let it all dry had the neg unplugged and I am getting p2302 with what seems like a misfire but no code.

Before I order the coils and spark plugs I am just making sure maybe its not something else. Money is super tight right now and I am a little unsure as this is a new issue after cleaning. I am newer to working on my jeep and cars in general. Really appreciate any help, thanks.

I also clean the battery contacts and didn't use dielectric grease
Click to expand...

Maybe since the plugs are so easy to do you should just pull them and inspect them first before buying? You could need injectors cleaned also since it's been sitting. I put 20oz of Techron into two consecutive tanks of fuel and it smoothed my idle out quite a bit.
 
Triggered said:
Maybe since the plugs are so easy to do you should just pull them and inspect them first before buying? You could need injectors cleaned also since it's been sitting. I put 20oz of Techron into two consecutive tanks of fuel and it smoothed my idle out quite a bit.
Click to expand...

I appreciate the reply and reassurance that the plugs are easy. Will pull the coils and plugs tomorrow.
 
macleanflood said:
Clean the IAC?

-Mac
Click to expand...

Hey Mac, I did. I did not take it apart but sprayed into the area with maf cleaner. My throttle body was not very dirty and cleaned up easly with the cleaner being sprayed. I sprayed in all areas of the throttle body until it ran clear.

20250911_165020.jpg
 
Torque710 said:
Hey Mac, I did. I did not take it apart but sprayed into the area with maf cleaner. My throttle body was not very dirty and cleaned up easly with the cleaner being sprayed. I sprayed in all areas of the throttle body until it ran clear.

View attachment 642786
Click to expand...

That might work. MAF is mass airflow and it's a delicate wire.

Typically we use carb cleaner.

Did you remove the IAC and spray out the passage?

-Mac
 
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macleanflood said:
That might work. MAF is mass airflow and it's a delicate wire.

Typically we use carb cleaner.

Did you remove the IAC and spray out the passage?

-Mac
Click to expand...

I didnt remove any sensors or the idle air control, I just sprayed maf cleaner into all opening until the spray ran out clean and blasted it a few more times for good measure. I sprayed into every orifice as well as rocked the butterfly back and forth while spraying both sides to get small amounts of carbon out. The throttle body was not very dirty and cleaned up easily with the maf cleaner. I used maf cleaner specifically so that I didnt have to disassemble the TB completely as its safe for the sensors. Maybe I should have disassembled it completely?
 
I will say after cleaning it all up and replacing the PCV it started and drove great! Better then I can ever remember and I was zipping around town for a few miles to test it all out when all the sudden cel and misfire. The coil and plugs were probably on their way out and im thinking that finally did them in. I have an ignition test pen coming tomorrow with spark plug socket, anti seize, and autolite xp985 spark plugs.

I will look for the misfire pull the plugs and put one of the old one in where the misfire is to see if its the plugs or the coils. If its the coils I have a blue streak in my RA cart to give it a go. Hoping its not a pcm issue
 
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macleanflood said:
What ohms do your coils measure out at? There's a value range in the FSM for testing purposes.

-Mac
Click to expand...

OK so i just checked. My misfire is in 1 and 6. Rail seems to be good. I just checked the boots. Google says around 15 ohms. Everything is around 15 ohms.

I have to clean the spark plug area (not the contacts) is pretty greasy and then I'll pull them and maybe swap. I have new plugs coming tomorrow.

20250914_183214.jpg


20250914_183141.jpg


20250914_183048.jpg
 
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Alright well the spark plugs looked pretty worn. Replaced those but I am still getting the cel p2302 with misfire or rough idle. Any thoughts?
 
1758069355318.png


Turn the ignition off.
Disconnect the coil rail harness connector.
Note: The following resistance measurement should be taken at 70-80
degrees F.
NOTE: The resistance of the 2.4L Primary Ignition Coil is 0.53 to 0.63 of an
ohm and the resistance of a 4.0L Primary Coil Rail is 0.51 to 0.61 of an ohm
at 70°F (21.1°C).
Measure the resistance of the Primary Coil Rail.
Is the resistance value within the noted specification for the coil being tested?
All
Yes ! Go To 4
No ! Replace the coil rail.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
 
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