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Desirayray

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Mine has 30 miles on it. It idles a bit rough when cold. I think its a lean condition....Maybe the fuel map is lean by design??
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JTPatriot

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Cold engines should run on the rich side until warm. They are running a open loop map until a set temp. is reached then they go closed loop and run off of the O2 sensors.
 
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JTPatriot

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Figure it is time to update this thread with my fix. I actually started to get multiple misfires with mine at the end. So I fixed it all by having the motor and trans swapped for a 5.7 hemi and truck 8 speed transmission. No more rough idle or misfires.
Hopefully those that are experiencing these issues at some time get a fix for it.
 

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Mine is occasionally a little "off" right after starting, but not a big deal. It settles down. I don't think it's anything to be concerned about. This engine is so much quieter than the JK, that I think I just notice the idle more.
Similar here with my new Gladiator, a bit of roughness with initial cold start at high idle ~1500 rpm, then as idle rpm drops so does the roughness. Once it settles it's a decent no-concerns idle. Initially had me wondering in comparison to my wife's Infinity QX60 very smooth 3.5 idle, but perhaps not an overall fair comparison if considering design for comfort vs design for jeep's rugged & ready systems.
 

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Is mine the only JT with 3.6 that doesn't run rough and hasn't experienced actual misfires?
I can tell when the AC is on now and then at idle, especially when cold, but it's not "rough" and isn't "missing".
 

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Is mine the only JT with 3.6 that doesn't run rough and hasn't experienced actual misfires?
I can tell when the AC is on now and then at idle, especially when cold, but it's not "rough" and isn't "missing".
I've had absolutely zero issues like that, but people who don't have problems don't usually post about lack of problems.
 

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Hate to bump this but I am having this issue. In cold starts idle is smooth till the temls gets around 145 and remained rough till it got to normal operating temps. No codes or check engine light on. If I give it Little gas and it smoothes out but when dropped to idle the rough idle will return. I've changed gas and upped the octane to see if there was a change. No change. Added red line fuel treatment and no change. My local dealers are less then stellar so Looking to get as much info as possible.

Just looking to see if anyone has had this issue and found a remedy. My jt ha 21k miles in it and has has 3 three oil changes by the dealer.
 

ShadowsPapa

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Hate to bump this but I am having this issue. In cold starts idle is smooth till the temls gets around 145 and remained rough till it got to normal operating temps. No codes or check engine light on. If I give it Little gas and it smoothes out but when dropped to idle the rough idle will return. I've changed gas and upped the octane to see if there was a change. No change. Added red line fuel treatment and no change. My local dealers are less then stellar so Looking to get as much info as possible.

Just looking to see if anyone has had this issue and found a remedy. My jt ha 21k miles in it and has has 3 three oil changes by the dealer.
Misfires have been caused by so many things just because one person "solved" a misfire doesn't mean their "solution" will even come close to helping your specific engine problem. It isn't like "any misfire can be solved by one of these 2 things". Doesn't work that way. You should document the details, even use a reader and software and capture the events to show the dealer.
Take it to a dealer. No treatment, no fuel change, nothing you do will resolve this one, I'd bet on it. It's temperature related. That points to an issue with the PCM and the information it's getting from sensors - perhaps an O2 sensor. I had an engine with O2 sensor heater circuit issues - roughness was very temperature related. It was just fine after it was run a while. (that's the simplistic explanation.

Octane has zip, zero, nothing to do with such misfires. Not even worth trying because octane is strictly resistance to self-ignition, it resists detonation. You have a misfire under specific conditions, not the ping of detonation - so don't waste your money on different fuels - fuel isn't your issue. Fuel would most likely cause issues when hot, unless it was OLD fuel and then it would most likely cause troubles when cold (because the light parts would be gone, only the heavy, which don't atomize or evaporate well, would be left)
Additives won't help - again, because this is temperature related at very specific temperatures. That should tell you right away - it's not what's in the tank, it's an engine control problem.

Transient misfires won't be stored. If it misfires now and then, and then smooths out, there will be no MIL (Malfunction Indicator Light) and no stored codes.

Here's an example of a very very nasty harsh misfire that caused the whole Jeep to feel like a bucking bronco - and look at what it says -Error warning lamp not requested......
When driving this thing on a test drive I made sure I had my cell phone with me as I was sure I was going to have to call for a ride back to my shop! It missed that badly and it bucked that badly on the road. Oddly it was only 1 cylinder.
The solution to this one was spark plugs.

This small part of the whole log was recorded sitting in front of my shop. (multiple logs, each several pages in length)


2021/01/04 11:56:32.011: Faults found: P0303
2021/01/04 11:56:35.970: Faults found: P0303
Error code: P0303
Cylinder 3 ignition failures
Test not complete
Error intermittent
Error warning lamp not requested

CARB Freeze Frame:
___________________
Fault code: P0303
PCM Mileage since MIL On: 0.00 miles
PCM Odometer: 950.27 miles
Open Loop - Bank 1: No
Closed Loop - Bank 1: Yes
Open Loop due to Driving Conditions - Bank 1: No
Open Loop with DTC - Bank 1: No
Closed Loop with DTC - Bank 1: No
Open Loop - Bank 2: No
Closed Loop - Bank 2: No
Open Loop due to Driving Conditions - Bank 2: No
Open Loop with DTC - Bank 2: No
Closed Loop with DTC - Bank 2: No
Engine load: 30.20 %
Freeze Frame Engine Coolant Temp: 66.00 Deg.C
Intake Air Temperature: 215.00 Deg.C
Ambient Air Temperature: 12.00 Deg.C
Short Term Fuel Trim - Bank 1: 12.49 %
Long Term Fuel Trim - Bank 1: -3.13 %
Short Term Fuel Trim - Bank 2: 9.37 %
Long Term Fuel Trim - Bank 2: -7.04 %
MAP Voltage: 1.96 V
MAP: 46 kPa
Atmospheric pressure: 97 kPa
Engine RPM: 875.00 rpm
Vehicle speed: 0 MPH
Throttle Position Sensor 1 Percent: 12.94 %
Battery voltage: 14.58 V
Fuel level: 95.69 %
Purge Solenoid Current: 0.00 mA
Purge Duty Cycle: 0.00 %
Idle Air Control (IAC) Current: 0.00 mA
Idle Air Control (IAC) Duty Cycle: 0.00 %
EGR Flow: 0.00 g/s
Current Adaptive Cell ID: 24
Spark advance: -2.00 Deg
AC Clutch: Disengaged
EGR Gassed Flowing: No
Power Steering High Pressure: No
AC Switch: Off
PRNDL in Gear: No
Brake switch: Pressed
Low Ethanol PWR Enrich Flag: No
Low Ethanol Therm Management Flag: No
Ethanol Gas For Sure: No
Ethanol Mode: No
Ethanol - 0% Blend Direction: No
Ethanol - 85% Blend Direction: No
Ethanol - Open Loop Fuelling: No
Ethanol Fine Tune Complete Previous: No
Ethanol Fuel Volume Changed: No
Ethanol Low Fuel: No
Ethanol Trigger On Fuel Volume Fault: No
Ethanol Trigger During Learn: No
Ethanol Learn: Disabled
Ethanol Course Update Ready to Learn: No
Ethanol Course Update: Not completed
Ethanol Fine Tune: Not completed
Actual Torque: 0.84 Nm
Potential Torque: 78.16 Nm
Target throttle position: 2.56 V
Electronic Throttle Control (ETC) Motor Directional Duty Cycle: -20.67 %DC
Electronic Throttle Control (ETC) Motor Duty Cycle: 20.67 %DC
Throttle position sensor 1: 2.58 V
Throttle position sensor 2: 17.42 V
Accelerator pedal sensor 10.44 V
Accelerator pedal sensor 20.22 V
Accelerator pedal position: 0.00 %
Brake switch 1: Released
Brake switch 2: Released
H-Bridge Circuit: Enabled
Ignition Run/Start Switch: On
Throttle Flow Adaptive: 0.13 g/s
Throttle Flow Multiplicative Adaptive: 2.00
PHI Adaptation Value: 0.00
Calculated MAP: 46.59 kPa
Ethanol Percent: 0.00 %
Turbo Boost Timer: 0.00 ms
Throttle Inlet Pressure: 0.00 kPa
Throttle Inlet Pressure Voltage: 320.34 V
Turbo Airport Mass Flow: 3.45 g/s
Turbo PRatio: 1.00
Turbo Torque Count: 0
Turbo Speed: 65535 rpm
Turbo Wastegate Duty Cycle: 200.01 %DC
Time since Run/Start: 45 sec
___________________
First Service Freeze Frame:
___________________
Fault code: P0303
PCM Mileage since MIL On: 0.00 miles
PCM Odometer: 950.27 miles
Open Loop - Bank 1: No
Closed Loop - Bank 1: Yes
Open Loop due to Driving Conditions - Bank 1: No
Open Loop with DTC - Bank 1: No
Closed Loop with DTC - Bank 1: No
Open Loop - Bank 2: No
Closed Loop - Bank 2: No
Open Loop due to Driving Conditions - Bank 2: No
Open Loop with DTC - Bank 2: No
Closed Loop with DTC - Bank 2: No
Engine load: 30.20 %
Freeze Frame Engine Coolant Temp: 66.00 Deg.C
Intake Air Temperature: 215.00 Deg.C
Ambient Air Temperature: 12.00 Deg.C
Short Term Fuel Trim - Bank 1: 12.49 %
Long Term Fuel Trim - Bank 1: -3.13 %
Short Term Fuel Trim - Bank 2: 9.37 %
Long Term Fuel Trim - Bank 2: -7.04 %
MAP Voltage: 1.96 V
MAP: 46 kPa
Atmospheric pressure: 97 kPa
Engine RPM: 875.00 rpm
Vehicle speed: 0 MPH
Throttle Position Sensor 1 Percent: 12.94 %
Battery voltage: 14.58 V
Fuel level: 95.69 %
Purge Solenoid Current: 0.00 mA
Purge Duty Cycle: 0.00 %
Idle Air Control (IAC) Current: 0.00 mA
Idle Air Control (IAC) Duty Cycle: 0.00 %
EGR Flow: 0.00 g/s
Current Adaptive Cell ID: 24
Spark advance: -2.00 Deg
AC Clutch: Disengaged
EGR Gassed Flowing: No
Power Steering High Pressure: No
AC Switch: Off
PRNDL in Gear: No
Brake switch: Pressed
Low Ethanol PWR Enrich Flag: No
Low Ethanol Therm Management Flag: No
Ethanol Gas For Sure: No
Ethanol Mode: No
Ethanol - 0% Blend Direction: No
Ethanol - 85% Blend Direction: No
Ethanol - Open Loop Fuelling: No
Ethanol Fine Tune Complete Previous: No
Ethanol Fuel Volume Changed: No
Ethanol Low Fuel: No
Ethanol Trigger On Fuel Volume Fault: No
Ethanol Trigger During Learn: No
Ethanol Learn: Disabled
Ethanol Course Update Ready to Learn: No
Ethanol Course Update: Not completed
Ethanol Fine Tune: Not completed
Actual Torque: 0.84 Nm
Potential Torque: 78.16 Nm
Target throttle position: 2.56 V
Electronic Throttle Control (ETC) Motor Directional Duty Cycle: -20.67 %DC
Electronic Throttle Control (ETC) Motor Duty Cycle: 20.67 %DC
Throttle position sensor 1: 2.58 V
Throttle position sensor 2: 17.42 V
Accelerator pedal sensor 10.44 V
Accelerator pedal sensor 20.22 V
Accelerator pedal position: 0.00 %
Brake switch 1: Released
Brake switch 2: Released
H-Bridge Circuit: Enabled
Ignition Run/Start Switch: On
Throttle Flow Adaptive: 0.13 g/s
Throttle Flow Multiplicative Adaptive: 2.00
PHI Adaptation Value: 0.00
Calculated MAP: 46.59 kPa
Ethanol Percent: 0.00 %
Turbo Boost Timer: 0.00 ms
Throttle Inlet Pressure: 0.00 kPa
Throttle Inlet Pressure Voltage: 320.34 V
Turbo Airport Mass Flow: 3.45 g/s
Turbo PRatio: 1.00
Turbo Torque Count: 0
Turbo Speed: 65535 rpm
Turbo Wastegate Duty Cycle: 200.01 %DC
Time since Run/Start: 45 sec
___________________
 

shrinkhead

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I applied the same fix as the OP and ripped the whole engine out and replaced it with a bigger one. that being said as shadows said: dealer time . before I swapped my engine it had 0 issues - should have probably kept it around
 

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This was issued a few days ago, seems related. I didn't look further, as I sold my Gladiator on Saturday.


Campaign Description
2020 JL JT 3.6L Misfire Detection - PCM Software Update
Repair Description
For more information please refer to the Owner Recall Notification by selecting the FCA Campaign #
Campaign Status
Incomplete but repair parts are available
 

shrinkhead

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This was issued a few days ago, seems related. I didn't look further, as I sold my Gladiator on Saturday.


Campaign Description
2020 JL JT 3.6L Misfire Detection - PCM Software Update
Repair Description
For more information please refer to the Owner Recall Notification by selecting the FCA Campaign #
Campaign Status
Incomplete but repair parts are available
What did you get ?
 

SwampNut

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What did you get ?
Nothing. Ever since we got a Tesla in April, I've put one tank of gas in the Gladiator. I rarely need a truck any more, and haven't been wheeling all that much either. So now worth having it, and people are overpaying for vehicles. And once you go Tesla you'll hate ICE.

Wife thinks we need two vehicles (we don't), so I am thinking either a super-cheap unpopular car like an old Leaf, or a sport UTV (we can license those for street here).
 

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This was issued a few days ago, seems related. I didn't look further, as I sold my Gladiator on Saturday.


Campaign Description
2020 JL JT 3.6L Misfire Detection - PCM Software Update
Repair Description
For more information please refer to the Owner Recall Notification by selecting the FCA Campaign #
Campaign Status
Incomplete but repair parts are available
I wonder if it was a campaign because no one was going in and letting the dealer do the flash, or the dealers weren't doing anything about it.

Would be interesting to find out the BUILD DATES of the vehicles getting these notices.
No one has said what their JT BUILD DATE was, only that they got a notice from carfax (and normally these come from Jeep, not a 3rd party)
 

shrinkhead

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Nothing. Ever since we got a Tesla in April, I've put one tank of gas in the Gladiator. I rarely need a truck any more, and haven't been wheeling all that much either. So now worth having it, and people are overpaying for vehicles. And once you go Tesla you'll hate ICE.

Wife thinks we need two vehicles (we don't), so I am thinking either a super-cheap unpopular car like an old Leaf, or a sport UTV (we can license those for street here).
the leaf is a great budget option - range just too short for most but I know a few folks leaf shopping right now. UTV would be fun!! you need a toy 🧸:)
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