Novak Conversions Jeep Wrangler JK radiators

3.6 Pentastar Misfire on Cylinders 1, 3, & 5

Artisanau said:
JKU_momma, I think so?

I thought I’d posted an update especially for the guys who were responsive to me at the time of my issues, but looking back I think not. Anyhow, in short because of how well it was running and not having the correct tools at the time, it was easy to overlook the basics.
I received the scanner, noticed trims running slightly rich. Found no leaks with smoke tester and no CO2 in water. Popped the intake manifold, compression test revealed low on #6 and 30% loss on leak down test. So interacting with Jeep to see if they’ll honour a repair and still waiting for a response, but its Dec and with Covid, I could be waiting a while as with everything else. I’ll have no option but to do it myself if I get a negative reply. The issue will be finding a new head thats not re-worked which there seems to be a lot of.
Click to expand...
Gotcha. I’m looking for a response from OP because my issue is exactly what he described in the first post, misfire on 1,3 and 5. I know there is a TSB for bad heads on the drivers side head. But I’m thinking that my issue may be the passenger side head.
 
Well, I’m at the end of the road with the misfire issue on #6 now readers.
I’ve contacted Jeep FCA Australia and finally FCA Detroit USA. Verbally over the phone and in writing as suggested by a forum member, no dice.. not even a written reply from the US? Had to call ’em? The spiel I got from the FCA US was almost identical to home here in Aus.
My 05/2013 build Vin Nō does not register with the effected build dates according to FCA, yet the issue is symptomatic of the known P0306 fault? There are Chrysler techs supporting the trend that more Pentastar 3.6’s are coming through now between 2013 and 16, so what do you think? I’ll tell everyone I meet to think twice before buying one, thats for sure. Previously I’d chop my ‘Co truck in for tax benefits every 3 yrs but this I purchased as a retirement gift to myself, thinking I’d brought something worthy of the $56k price tag on it. I honestly thought I would see more than 46k miles on the clock before I encountered serious mechanical issues like I have. Burnt out exhaust valves on one cylinder and possibly going on 3 as well? I don’t care what line Chrysler want to spin, but I smell a rat. I read an article that especially in Aus, Chrysler chiefs are trying to reach out with advertising to recover the drop in sales over the last 10 yrs, but the answer is simple, just look after the customers that are already loyal to the brand and they will return and trend will follow them. Its been documented via a US court case that Chrysler never released all the effected Vin Nō’s associated with this fault, so of course its sending out negative vibes to me and I can only source so much info and verifying it is another thing. For every person I tell of my experience, it’ll loose Jeep a sale of $80k AU and I’ve already saved one soul. I’ve never mentioned it in hope of giving leverage, but I was giving my JK to my daughter with the intension of getting the 6.4 SRT GC in Sting Grey, Yum, but I can spend my $’s elsewhere just as easy as bending over in my local Jeep dealership. You know I love my Jeep, had it 7 yrs now, its been magic. The faults not with it, every make of car has issues, beit a Fiat or a Bentley, its the way in which your dealt with after the sale and by the manufacture. I can’t even blame the dealership really, their hands are tied by the warranty dept of Chrysler, they can only do what they can do, but someone out there on mega bucks, needs to think outside the box they’re in? Ever tried contacting someone to talk to within the warranty dept at FCA by phone with exception of the robotic receptionist, no chance. Got more chance of sitting out on your deck at night and engaging with aliens. Cheers readers and thanks for all the previous contact, suggestions and help, it was appreciated. 👊
 
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MDuncan said:
Hi Folks,

Looking for your expertise.

The problem: Random Misfires on cylinders 1,3,5 - Confirmed with Scanner
The Jeep: 2012 JKU 6-Speed, 108K miles
How long: I've been trying to fix this: 9 months

It's hard to feel the misfire when under throttle, but you can hear and feel the slight misfire trembles when at idle.

What I've tried so far:
- New Spark Plugs: (2 set's - 6 NKG & 6 Champion) Properly Gapped
- New Coils: MSD
- New O2 Sensors (all 4 - both sides)
- New Crankshaft Position Sensor
- New MAP Sensor
- All new Rocker Arms and Lifters on that bank (Cyl 1,3,5)
- New Camshaft Position Sensor
- New Injector on Cyl 5 = No change still misfiring
- New upper and lower o-rings for injectors
- New upper and lower o-rings for Lower and Upper Manifolds

Tests Completed:
- Leakdown Test Showed Normal
- Rotated Coils - No Change
- Rotated Plugs - No Change
- Camshafts inspection - no flat spots found

Additional Modifications Possibly Affecting Performance:
Mishimoto Oil Catch Can
Banks CAI
Odyssey Battery

Additional Fixes Completed on Motor:
- New Oil Pressure Sensor


Friends,
Please help. I love my jeep, and I want to drive it to 300k miles and drop in a Hemi and keep driving it.

(Wave),
Matt
Click to expand...
;) .... Sorry to laugh but you made the classic error many do it yourself guys make; throwing parts at the problem at a problem until it goes away. That hasn't worked since cars got computers.
I was told to replace the transmission by 3 dealers and AAMCO but the problem ultimately turned out to be a $9.00 throttle position sensor. So:
I suggest a mechanic. The kind with the $5,000 scanner and background knowledge of the Pentastar to properly diagnose the problem. Cost less than you've wasted.
 
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I had the same thing happen to a 2008 Wrangler I once had. I replaced every sensor in that durn thing and no luck. Especially when speeding back up from making a turn. I finally gave up and took it to a shop where they had one of those 3 thousand dollar diagnostic machines and promptly told that the spark plug wires were leaking. The wires look like new to me but I went to Napa and bought a set their high budget wires. After that it ran perfect. The wires for 1-3-5-7 run behind the engine and apparently it gets too hot back there.
I ran the new ones over the top. I now have an inventory of 2008 3.8 engine sensors including the coil pack. All but the O2 sensors.
 
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I had to check a fuse. It was hot as hell and I had to use tools.
Maybe Jeep engineers built the engine cooling with highway cruising in mind.
Anyway, once I get past my cheapness, hood vents.
 
MDuncan said:
Hi Folks,

Looking for your expertise.

The problem: Random Misfires on cylinders 1,3,5 - Confirmed with Scanner
The Jeep: 2012 JKU 6-Speed, 108K miles
How long: I've been trying to fix this: 9 months

It's hard to feel the misfire when under throttle, but you can hear and feel the slight misfire trembles when at idle.

What I've tried so far:
- New Spark Plugs: (2 set's - 6 NKG & 6 Champion) Properly Gapped
- New Coils: MSD
- New O2 Sensors (all 4 - both sides)
- New Crankshaft Position Sensor
- New MAP Sensor
- All new Rocker Arms and Lifters on that bank (Cyl 1,3,5)
- New Camshaft Position Sensor
- New Injector on Cyl 5 = No change still misfiring
- New upper and lower o-rings for injectors
- New upper and lower o-rings for Lower and Upper Manifolds

Tests Completed:
- Leakdown Test Showed Normal
- Rotated Coils - No Change
- Rotated Plugs - No Change
- Camshafts inspection - no flat spots found

Additional Modifications Possibly Affecting Performance:
Mishimoto Oil Catch Can
Banks CAI
Odyssey Battery

Additional Fixes Completed on Motor:
- New Oil Pressure Sensor


Friends,
Please help. I love my jeep, and I want to drive it to 300k miles and drop in a Hemi and keep driving it.

(Wave),
Matt
Click to expand...





Matt, Kinda hiliarious and a total long shot but you are basically driving my jeep with the same exact problem and I"ve thrown the sink at it as well. Chasing my tail for an electrical issue I firmly believe. Curious if you ever found the root issue. Thanks! I know it is a year later but why not


Jeep 2012 108K miles 6 Speed Man

Missfiring Random Cylinders 1,3,5

Checked injectors, Coil, new plugs, new bank 1 cam sensor. Compression is good 150lbs cat is not plugged, tested with a gauge. Got all new 02 sensors too.

None of the above seem to move the problem. Checking harnesses but i'm guessing your issue is the exact same rubbing spot somewhere in it.

Thanks

Jason
 
I purchased my 2013 JK Auto in March 2019 and have been getting misfiring codes on Bank 1 (most misfiring is happening on Cylinder 3) since I bought it.

Things i have tried:
  • Camshaft position sensor
  • New ECU
  • Bank 2 wiring loom (fixing another issue)
  • Checked wiring loom
  • 6 x new coils
  • 6 x new spark plugs
  • New lower manifold and seals
Next on my list:
  • Catalytic Converter (getting code for this now, probably related to misfire)
  • O2 sensors
  • Injector clean
  • PCV valve
Valve cover is off at the moment while i wait for new valve cover gaskets but rockers look all good.

I originally suspected electrical issue but now im not so sure. Any other ideas?
 
jszeinstra said:
Matt, Kinda hiliarious and a total long shot but you are basically driving my jeep with the same exact problem and I"ve thrown the sink at it as well. Chasing my tail for an electrical issue I firmly believe. Curious if you ever found the root issue. Thanks! I know it is a year later but why not


Jeep 2012 108K miles 6 Speed Man

Missfiring Random Cylinders 1,3,5

Checked injectors, Coil, new plugs, new bank 1 cam sensor. Compression is good 150lbs cat is not plugged, tested with a gauge. Got all new 02 sensors too.

None of the above seem to move the problem. Checking harnesses but i'm guessing your issue is the exact same rubbing spot somewhere in it.

Thanks

Jason
Click to expand...

I'm surprised no one has suggested pulling the head on that side and checking the head/gasket.

The 2/4/6 misfire on the pentastar is a very common problem, requiring a replacement head. Stands to reason the same problem could exist on 1/3/5.

Apparently the problem is that heat damages the valve seats leading to all kinds of issues, including misfires on the entire bank.
 
IndyDoF said:
I purchased my 2013 JK Auto in March 2019 and have been getting misfiring codes on Bank 1 (most misfiring is happening on Cylinder 3) since I bought it.

Things i have tried:
  • Camshaft position sensor
  • New ECU
  • Bank 2 wiring loom (fixing another issue)
  • Checked wiring loom
  • 6 x new coils
  • 6 x new spark plugs
  • New lower manifold and seals
Next on my list:
  • Catalytic Converter (getting code for this now, probably related to misfire)
  • O2 sensors
  • Injector clean
  • PCV valve
Valve cover is off at the moment while i wait for new valve cover gaskets but rockers look all good.

I originally suspected electrical issue but now im not so sure. Any other ideas?
Click to expand...
I had same issue a while ago with my other jeep and end up being a broken valve spring on cylinder 3
 
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MDuncan said:
Hi Artisanau,

Happy to jump back in.

To make sure I understand:
- Your jeep is misfiring on #6 or all cylinders on that bank?

To answer what I have done to my jeep:
Thus far I have not been able to completely cure my misfire(s), but I have tried some additional fixes sense my original Post.

They were:
- Full Engine wire harness @Chris
- Partial wire harness for left bank injectors

I do continue to think my issue is electrical, Fuel, or Intake leak (causing it to run slightly lean). This would all make sense considering you need three things to get an engine running: fuel, air, & spark.


So, in order, what am I going to do next?
- Check fuel pressure from the tank to fuel rail and replace the pump if low pressure is found
- Replace PCV valve
- Replace all breather/intake hoses

What else is going on?
- Well, it just threw P0128 - Thermostat Rationality - Likely the thermostat is stuck open.



Apologies for not being much more help,
Matt
Click to expand...
Hi Matt, Same issues on my 2013 JKU.
Same as you:
 
MDuncan said:
Hi Artisanau,

Happy to jump back in.

To make sure I understand:
- Your jeep is misfiring on #6 or all cylinders on that bank?

To answer what I have done to my jeep:
Thus far I have not been able to completely cure my misfire(s), but I have tried some additional fixes sense my original Post.

They were:
- Full Engine wire harness @Chris
- Partial wire harness for left bank injectors

I do continue to think my issue is electrical, Fuel, or Intake leak (causing it to run slightly lean). This would all make sense considering you need three things to get an engine running: fuel, air, & spark.


So, in order, what am I going to do next?
- Check fuel pressure from the tank to fuel rail and replace the pump if low pressure is found
- Replace PCV valve
- Replace all breather/intake hoses

What else is going on?
- Well, it just threw P0128 - Thermostat Rationality - Likely the thermostat is stuck open.



Apologies for not being much more help,
Matt
Click to expand...
Hi Matt, Same issues on my 2013 JKU.
Same as you:
- New Spark Plugs: 6 NKG Properly Gapped
- New Coils: MSD
- New O2 Sensors (all 4 - both sides) Bosch
- New Crankshaft Position Sensor - OEM
- New MAP Sensor - OEM
- New Camshaft Position Sensors

Now waiting for new injectors.

Did you manage to solve the issue???

I do see about 3.5% fuel trim - not sure its relevant.


Thanks so much,
Robert.
 
This is incredible. I really hope some of you find the resolve. It so happens I spoke with a mechanic who's team works on these engines (one a week, according to him) and it's always a head, rocker followers, cam wear or shot lifters that they're repairing / replacing.
 
Doesn't make sense, I ran a compression test and I have 150psi on all 6 cylinders - if it was stuck lifter wouldn't that cause compression issues? Really starting to hate Chrysler products. Coming from v8 GMs and Toyotas - never even heard of these issues.
 
"If it was a stuck lifter wouldn't that cause compression issues?"

@Rdartua That's a good question. Maybe not? if it's just one lifter then Id think, at the least, it would cause a slight ticking noise.

To be clear, my post about the mechanic that I spoke with isn't meant to be a suggestion per se about your particular engine but to say that the 3.6 certainly has it's commonly known issues.
 
Quick update:
Opened both valve covers and checked out valves and cams - look perfect no ticking or sticking.
Got all the new injectors, will install this weekend and update. Btw installing newer version of Bosch injectors from 2018-2020 model. Other forum members used them with no issues - better flow and half the price.
Also tested all injector wires using node light - all good.

Hopefully injectors will solve the issue, however all all injectors worked from what i could test
 
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I wish, no go, reset ECU after new injectors install and now misfire came back as CYL#2. Interestingly enough it comes back on a second vehicle start. Meaning the first start car runs like new - no issues a r all , then I let is stand for say 2 hours start again and you can hear the misfire on low rpm. Honestly this is beyond frustrating. I ended up buying WiTech dongle clone will run diagnostics tomorrow. How convoluted can this issue be?? After working on cars for fun for better part of 30 years, this is the first time when I am stumped by an engine issue that cannot be traced. I will take it to the dealer this week if I am not able to diagnose it, dont even know what my next step would be,
 
Thats a muther effer. You don't have any modern mechanics in your area? I just know dealers are hit or miss, with mostly a miss and a slam to the wallet.
 
Update - Leak-down came in with less then 1% loss - so no problems there. Got PCM from flashmasters, same cyl1 and Cyl2 misfire at idle only. I have no idea what else could possibly cause this. SO, decided to bite the bullet and take it to a "highly rated" dealer, Garavel Jeep in Westport CT with issue quickly going from $165 diagnostic to $500 with no answers as of yet. Will update if dealer is able to solve the issue

​

 
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