3.6 Codes issue & diagnoses

[ucijeepguy]

I wanted to see if I can get help narrowing down my issues exactly. After brief comments from @ShadowsPapa I decided to go out and record some data to try to narrow down what my issue is exactly. I'm hoping the data in the pictures can help. seems off to me, but im not a mechanic.

Symptoms: slight ticking, stumbling, less power than it seemed before.
When I started it up to record today it stumbled really bad like a manual stalling (its automatic) and i shut it off. restarted and it went away (possibly due to warming up?) but still will feels weak and stumbly when driving.

2020 Jeep Gladiator 3.6 Gas
Mileage 87,898
Spark plugs & coil packs replaced about 85k?.

I visually inspected the 02 sensors and does not have excessive oil covering as some had mentioned there may be head gasket leak leaking on to the O2 potentially causing issues, these looked the normal amount of dirt covered plugs for the O2.

The codes and images are from my harbor freight ZR13s scanner and attached app.

Pending/confirmed Codes:
P0300 Random/multiple cylinder misfire detected
P0301 Cylinder 1 misfire
P0420 Catalyst system efficiency below threshold (bank 1)
Permanant:
P0300
P0301

Thanks for any help you can provide!!

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[Lost1wing]

P0420 is from driving it with a misfire for too long. If you replaced coils and sparkplugs already, you can try moving a known good coil to the nbr one position. Even side is more notorious for cam, rocker issues but not unheard of on the other side. ShadowsPapa will have a better idea with the data.

 

[Lost1wing]

Does your scan tool report misfire count? I wonder if you have a hard nbr 1 misfire and a random misfire on the even bank.

 

[Lost1wing]

If you look at,your scan tool in mode 6, you are looking for the O2 sensors to toogle , something like 1v to mil volts. Your O2 sensors are not going to function normal with a misfire. The O2 sensors will see the rich mixture and the computer will compensate by reducing fuel. It can only reduce the fuel by so much. So to start with, you need to correct the misfire on nbr 1 and any other cylinder that you see on a misfire count.

 

[Svenable]

Did you have this problem before you changed plugs and coil packs? If not, I would think about looking there. I am personally acquainted with people, (2), that "upgraded" the coil packs to aftermarket ones and soon developed misfire issues. The OEM coil packs are very difficult to improve on.

You could swap the coil packs and plug between cylinders 1 and 3 to see if the misfire moves with the plug and coil pack. If it does move I would suspect the coil pack. If it does not move you now have good data it is not the the coils or plugs.

I agree that the O2 sensor readings are probably affected by the misfire issue. I would recommend getting the misfire fixed first.

 

[ucijeepguy]

P0420 is from driving it with a misfire for too long. If you replaced coils and sparkplugs already, you can try moving a known good coil to the nbr one position. Even side is more notorious for cam, rocker issues but not unheard of on the other side. ShadowsPapa will have a better idea with the data.

Sorry, what do you mean moving to a known good coil to the NBR one position? as in make sure the coil pack is working correctly?

 

[ucijeepguy]

If you look at,your scan tool in mode 6, you are looking for the O2 sensors to toogle , something like 1v to mil volts. Your O2 sensors are not going to function normal with a misfire. The O2 sensors will see the rich mixture and the computer will compensate by reducing fuel. It can only reduce the fuel by so much. So to start with, you need to correct the misfire on nbr 1 and any other cylinder that you see on a misfire count.

I figured the O2 is compensating for the misfire, and ECU is reducing fuel based on the LTFT B2 is -10 compared to the others. If I'm understanding that correctly.

Thats the hard part is figuring out how to correct the misfire. I don't have the money to take it to a shop so trying to get as far as I can myself, nor can i afford to throw money at non resolving items. I was hoping the coil and spark plugs were enough, but obviously not.

I'm assuming I don't need to replace a faulty O2 because that's a symptom of the misfire, possibly camshaft position sensor and silonoid?

 

[Lost1wing]

If you swap nbr 1 with nbr 2 and the misfire moves, you know you have a bad coil pack. You can do the same with the sparkplug. Just because they are new doesn't mean they are good.

It does seem like you have more than one cylinder with issues. P0300 could be something else like you have mentioned.

I'd start with nbr 1.

 

[ucijeepguy]

Did you have this problem before you changed plugs and coil packs? If not, I would think about looking there. I am personally acquainted with people, (2), that "upgraded" the coil packs to aftermarket ones and soon developed misfire issues. The OEM coil packs are very difficult to improve on.

You could swap the coil packs and plug between cylinders 1 and 3 to see if the misfire moves with the plug and coil pack. If it does move I would suspect the coil pack. If it does not move you now have good data it is not the the coils or plugs.

I agree that the O2 sensor readings are probably affected by the misfire issue. I would recommend getting the misfire fixed first.

The check engine light was there before the plug and coil replacement, which when I took it to Christian brothers they said it needed new coil and plug, but for $1,200, I did it myself. Issue persist and has gotten worse since.

I recently did a trip few hundred miles away and my friend was driving, we had to stop every 10 miles to drop off a cache for his hike, being next to the highway he would floor it, and immediately after that trip its gotten worse. I dont know if its related, but the hard throttle seemed to make it worse.

 

[ucijeepguy]

I swapped the passenger side front two plugs (hopefully that's the correct to test?) and immediately upon start it was heavy stumbling and could smell fuel out of the exhaust.
The check engine light stayed on the same cylinder 1 and multple cylinder code., codes didnt change. Unless I didnt run it for long enough, but the stumble was so bad I didnt want to run it toooo long, it was long enough to warm up.

 

[ShadowsPapa]

I recently did a trip few hundred miles away and my friend was driving, we had to stop every 10 miles to drop off a cache for his hike, being next to the highway he would floor it, and immediately after that trip its gotten worse. I dont know if its related, but the hard throttle seemed to make it worse.

Heavy throttle forcing it into the 3,000 RPM and above range, especially the ABOVE part, means if there was cam lobe and follower wear before - he just made it worse.

 

[Hootbro]

I swapped the passenger side front two plugs (hopefully that's the correct to test?) and immediately upon start it was heavy stumbling and could smell fuel out of the exhaust.
The check engine light stayed on the same cylinder 1 and multple cylinder code., codes didnt change. Unless I didnt run it for long enough, but the stumble was so bad I didnt want to run it toooo long, it was long enough to warm up.

Running out of things to swap and that leaves a possible fuel injector or valve/valvetrain problem on the #1.

 

[ucijeepguy]

Heavy throttle forcing it into the 3,000 RPM and above range, especially the ABOVE part, means if there was cam lobe and follower wear before - he just made it worse.

Thats kind of what I figured. Obviously not his fault.

So the question remains, where is a good place to buy/order a quality cam. Is the newer cam better? Can I swap the newer year cam and then drive it to dealer and have it flashed?

 

[Hootbro]

If it was me, I would be taking off the passenger valve cover and taking a look for damage before getting all wound up ordering parts.

Like mentioned, there is still the fuel injector or command circuit check for it and also doing a cylinder compression check on that #1 that can be done

 

[ucijeepguy]

If it was me, I would be taking off the passenger valve cover and taking a look for damage before getting all wound up ordering parts.

Like mentioned, there is still the fuel injector or command circuit check for it and also doing a cylinder compression check on that #1 that can be done

What is command circuit? how do I check that? Thanks

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