2011 KK (Liberty) CEL - Need Advice


Caught the Bug
Anna, our 2011 KK (Liberty) has been sick for the last couple of months. CEL is illuminated carrying a P0302, miss-fire cylinder #2. I’ve been dinking around for awhile and now I’m running out of bullets. I’m hoping to tap into the wealth of forum knowledge here at Wayalife.

A little background on the KK engine; this 3.7L has COP (coil over plug) only on one side of the engine, cylinders 1, 3 & 5. Cylinders 2, 4 & 6 use plug wires that run across the engine. Subsequently the following cylinders share coils 1 & 4, 3 & 6 and 5 & 2. This engine has 115k miles on it and only had one coil replaced in the past - no other work ever done.

What I’ve done:
1. First time CEL illuminated I got 4 codes, in order:
- P0302, miss-fire cylinder #2
- P0581, Cruise Control Multi-Function Input A Circuit High
- P0579, Cruise Control Multi-Function Input A Circuit Range/Performance
- P0585, Cruise Control Multi-Function Input A/B Correlation
The engine was truly miss-firing! I wasn’t really concerned with the cruise control codes since it has worked/not worked for a couple of years, but this was the first time seeing the codes for the cruise [emoji848].
I had a P030X problem years ago and fixed it with a new coil. We were leaving on a cruise in few days so I took a shot and replaced the coil and all six spark plugs. That seemed to fix the problem for about a month.

2. CEL returned - P0302 was the only code. It illuminated shortly after a cold start, but the engine didn’t seem to be miss-firing. I swapped the new coil with a different one and reset the PCM.

3. A week later the CEL was back. Again, P0302 and after a cold start, but didn’t seem to be miss-firing. This seems to be a recurring theme. Swapped the plug wire and reset.

4. A few days later, CEL is back, same as before plus the P0581 and P0589 came back. Checked compression thinking maybe I have a head gasket issue. Warm compression looked good at 195psi, cold at 175psi. Range should be 175 to 225psi so that seems ok.
I checked the coolant level which was good, smelled the coolant, no fuel and check the oil. I also checked the exhaust at cold start. No excessive smoke or coolant smell. Every looked good so I’m ruling out the head and gasket. For shits and giggles I swapped the third and final coil and reset.

5. Of course the CEL came back, same as before. I took the next step and swapped fuel injectors and reset.

Present day - CEL is back, just P0302 as before. Doesn’t seem to be miss-firing and I’m running out of bullets. Thinking that I might have a bad crankshaft position sensor, but I would think that would throw a P0300, multiple miss-fire? Or is it just a failing PCM?

I think I’m going to order a ODB2 scanner adapter for my phone:


Anybody have any experience with this? I want to see if the engine is really miss-firing using live data in the auto doctor app. Or is there a better app?

Thank you in advance for reading through all this detail! If you have any thoughts, advice or further questions, please drop a line.

Sipafz - Chris
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Meme King
Hate to be the bearer of bad news, but I see a lot of 3.7s with loose valve seats. Not saying that is the case with yours but it wouldn't surprise me. Sounds like you've done everything else. Strangely your compression is within specs. Maybe try a leak down test just to see.


Caught the Bug
Hate to be the bearer of bad news, but I see a lot of 3.7s with loose valve seats. Not saying that is the case with yours but it wouldn't surprise me. Sounds like you've done everything else. Strangely your compression is within specs. Maybe try a leak down test just to see.

Thanks! I will definitely do that before taking it in!


Caught the Bug
I got my scan tool today:


I take it out to the Jeep, plug it in start the engine and no MIL. Still had a P0302 stored. Viewed the live data and the engine was firing normally. After 20mins and a short drive I had the following:

Cylinder - Misfire

Question: How many is needed to illuminate the MIL? Is it so many per minute?

It was warm today at 40F. It’s suppose to be cold Sunday morning, so I will repeat the test then.


Meme King
I don't know the answer to your question as to how many counts the pcm needs, but what a weird issue. It may not be a bad idea to run a can of BG 44K through the fuel system in the event there's some bad gas or sticking valves. Only other thing I can think of is your primary ignition wiring, fuel injector wiring, or the pcm itself. Any signs of rodent damage?


Caught the Bug
I don't know the answer to your question as to how many counts the pcm needs, but what a weird issue. It may not be a bad idea to run a can of BG 44K through the fuel system in the event there's some bad gas or sticking valves. Only other thing I can think of is your primary ignition wiring, fuel injector wiring, or the pcm itself. Any signs of rodent damage?

I’ve beed reading up on the issue and found the following:

“If the code set when the engine was cold, chances are the OBDII system is being overly sensitive and there is no real misfire problem. Check for any technical service bulletins (TSBs) that may be out on the vehicle for false misfire codes. The cure, in many instances, is to flash reprogram the PCM so the OBDII system will be less sensitive to misfires.”

I have found this practice of raising the limits in a few different places now. Sounds a bit like turning a blind eye, but if that’s possible, who am I to judge?

Yes, I have some evidence of rodents gnawing on the hard plastic protecting the battery and alternator positive terminals. I haven’t seen anything else on the harnesses or wires.

Things to do:
- Check for cold misfires with scan tool
- Perform leak down test
- Check plug voltage at the coil and injectors
- Inspect wires and harness, again
- Check spark plug wires with multimeter
- Treat fuel system for water and add injector cleaner

I’m not familiar with BG 44K so I will have to check into that! Thanks for the tip!


Meme King
I’m not familiar with BG 44K so I will have to check into that! Thanks for the tip!

There's a lot of snake oil on the market, but I can honestly say that this shit produces immediate results in regards to cleaning out carbon. Primarily in regards to pinging. When I worked in shops, I had many customers call back within a week saying their pinging was fixed after adding a can of this.

So, if there are any abnormal fuel deposits where your injectors spray, this stuff will clean it up.


Caught the Bug
An update on this: Last January when I was having issues with this misfire the weather suddenly changed, staying above freezing and the issues went away.

November came round and of course the temps started dropping. CEL came on and confirmed misfire with scan tool. Swapped coils and problem moved with the swap so I replaced the coil. Problem solved for 6 weeks.

Last week the CEL came back. Scan tool showed misfires on all passenger side cylinders:

2 - 30

4 - 2

6 - 10

Cylinder 2 was throwing the code and was the only cylinder still using an OE coil. I replaced it with a new one. For the first time a new coil did not remedy the problem.

Currently I have a minor misfiring on cold starts, only when the temperature is below freezing. Once the engine gets warm the misfire stops and everything is ok, just the CEL remains. I’m going to dig deeper on this and bought a leak down tester. More to come.



Caught the Bug
I think I picked a bad day to do this leak down test. I had a hell of a time getting consistent readings from the gauges. They seamed to be freezing up while I was using them. I suppose it didn’t help that I had them hooked directly to the compressor without a dryer or filter. I was able to confirm that nothing major is mechanically wrong with the engine, but I’m going to perform this test again on a warmer day.

Cylinders 1,3,4 & 5 were at 32 to 38% which is normal air loss. I didn’t hear any loss at the intake or exhaust nor did I see any bubbles in the coolant overflow. I could hear air going past the rings into the crank case. I noted the volume/pitch as normal.

Cylinder 6 was at 44% which is moderate air loss. I could hear air escaping from the intake valve at the throttle body.

Cylinder 2 (the one throwing the code) was at 40% which is the line between normal and moderate air loss. I could not hear any escaping air at the intake or exhaust, no coolant bubbles and the crank case volume/pitch sounded the same as the other passing cylinders.

For fun, I repeated a compression test on the passenger side of a warm engine:

2 - 205
4 - 200
6 - 190 - leaking intake valve?

So nothing found that actually pinpoints the problem. I ordered a bottle of BG44k Fuel System Cleaner per Dougs recommendation. Hopefully that will address the leaking intake valve on #6. I also got a new set of ignition wires since the misfires are all happening on the wire fed side of the engine.
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Meme King
Are you getting those leak down specs from the service manual or from instructions that came with the tester? 30-44% seems high to me.

As far as your compression numbers, those seem close enough to not worry about IMO.


Caught the Bug
I don’t know what the actual specs are yet. I’m just going by the gage. Like I mentioned, I was having issues with the gage due to how cold my garage is. I’m going redo the test on a warmer day which may led to the gauge reading differently.

I’m encouraged by that I couldn’t hear or see any glaring problem. I started it up this morning and the CEL remained off.


Caught the Bug
Update: After a week of the harshest weather this season, I was cautiously optimistic that the plug wires were the issue. No CEL during the stretch of -30 temps. Unfortunately as the temps got closer to freezing the CEL came back on, P0302. I took a look and as I was moving around the new plug wires I noticed a manifold bolt/stud with a wire route clip rotate. Not just the clip, but the whole stud rotated. I tightened it back to 105 in/lbs and checked all the other bolts. I found that the bolt next in line was also loose and as luck would have it these loose bolts were by cylinder 2 & 4. I have no idea how those bolts would come loose as I have never touched them in the past. Anyway, those are tight and will see if that makes a difference. Maybe a vacuum leaking was happening during cold start and improved as the engine warmed?

I got my bottle of BG44K and added it to the fuel system. I plan repeating the leak down test in a few weeks and hope this stuff helps the minor leak on the #6 intake valve.

New complaint from the wife is that the heat is blowing cool on the drivers side and hot on the passenger side. I’m going to flush the heater core today. 3 more years and I’ll be happy to let this Jeep go in trade for a new JLU or JT


Caught the Bug
Update: November 2019

As per usual, this Jeep Liberty ran good with no issues the entire spring, summer and fall of 2019. Once the weather got colder the CEL retuned. The diagnostic tool showed the normal P0302, misfire cylinder #2 with a low double digit weighted average (40 or so). Nothing to keep from using the vehicle on a daily basis. Fortunately, the cold snap was short and I was able to spend some time with the Jeep the following weekend.

I started with repeating the leak down test. The garage temperature was in the 50’s and I found that the tester and gage were repeating which gave me confidence in the test. Results were an average pressure loss of 15% with the suspect cylinders of #2 & #6 being on the lower end of the average.

Since I didn’t find anything definitive, I started the vehicle connected the scan tool and started to track misfires. What I noticed is that if I put the vehicle in gear with the brakes on and let the engine idle (roughly 600 rpm) the engine will misfire once every ten seconds maybe. This happens whether the engine is cold or hot and is most prevalent when in gear, brakes on and at idle.

To confirm this result I took the vehicle out for a drive with the scan tool continuously collecting data. No additional misfires are reported during normal driving. The misfires do return if I pull of the road and idle as described above.

I’ve come to the conclusion that the cold weather exasperates the situation by letting the vehicle idle to warm up. The fact that the engine seams to misfire more at lower idle rpm is interesting and that having the vehicle in gear with the brakes on has me thinking I might has a vacuum leak somewhere? My next step is to look for a leak. In the meantime I ordered a gage to help aid in the search:


As always, please let me know if you have any ideas on additional things that I should consider.



Caught the Bug
Thread revival here. Another year and the same issue is back with our Liberty - misfire cylinder #2.

Last winter I messed around with performing a vacuum test and a couple other minor things. The Jeep didn’t give me much trouble and due to COVID, my wife has been working from home since February. As a result, the Jeep rarely is driven and had no problem passing emissions last summer.

Now that winter has set in, we are seeing misfires again. I have some time off work for the holidays so I dove back in determined to solve this annoying issue or pay someone to do so.

Like always I started with the basics:
- Checked Spark Plug, visually looks ok
- Checked Spark Plug Wire with OHM Meter, resistance is within specifications
- Swapped Ignition Coil, no improvement
- Swapped Fuel Injector, no improvement

Since none of that had any impact, I swapped the Crankshaft Position Sensor with our 2003 Liberty, no improvement

Swapped the ASD Relay with a different one in the fuse box, no improvement

Replaced the Camshaft Position Sensor since it was cheap, no improvement

Even though I did a compression test and leak down test last year, I bought head gasket test kit that detects fuel in the coolant, test was negative:


Running out of ideas, I decided to pull the valve cover to inspect the rockers and lash adjusters. I immediately found that two rocker arms seemed loose or wobbly. On those rocker arms I was able to push the lash adjusters in with my fingers, easily squeezing all the oil out of them. Finally on to something? The others that had closed valves seemed rock hard and I could hardly compress them with my fingers.

I pulled the coils, wires & plugs so I could rotate the engine with a ratchet at the harmonic balancer as I needed to re-position the camshaft to check the rest. In all I found 3 of 6 lash adjusters to be bad. I popped out all the rockers and removed the adjusters to inspect:

Bad Lash Adjuster https://youtu.be/r8h0CI4TokU

Ended up ordering 6 new adjusters since they were cheap - Melling $12.99ea

I have them soaking in oil overnight so I can install them tomorrow morning:


I think I finally got to the bottom of this issue? Time will tell.
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