14' JKU w/ 89K miles seems sluggish

naysjp

naysjp

Caught the Bug
14 JKU w/ 4:88 gears and 35s. No check engine light, no codes. I had the regear done in 2018 a couple of months after getting the EVO Enforcer lift put on. The Jeep shot down the freeway like a rocket after being re geared. December 2018, I had the oil filter cooler replaced at the dealership as warranty work and the Jeep ran fine. I did put the ProCal in the OBD port again in case the dealership flashed it without telling me. The last month it starting feeling sluggish, not so much pep so I changed the oil as it was time and put in a new air filter. I put a bottle of Lucas Fuel treatment in the tank followed by a tank full of mid grade gas (I always use 87). That did nothing, still feels sluggish. I checked the tire pressure and that is good. It is time for new front brakes but that's all. Differential fluid is fine. I read a few posts that said their JKs were sluggish but nothing worked. Working towards taking the Jeep out on a run and I want to make sure I get back home.
 
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naysjp said:
14 JKU w/ 4:88 gears and 35s. No check engine light, no codes. I had the regear done in 2018 a couple of months after getting the EVO Enforcer lift put on. The Jeep shot down the freeway like a rocket after being re geared. December 2018, I had the oil filter cooler replaced at the dealership as warranty work and the Jeep ran fine. I did put the ProCal in the OBD port again in case the dealership flashed it without telling me. The last month it starting feeling sluggish, not so much pep so I changed the oil as it was time and put in a new air filter. I put a bottle of Lucas Fuel treatment in the tank followed by a tank full of mid grade gas (I always use 87). That did nothing, still feels sluggish. I checked the tire pressure and that is good. It is time for new front brakes but that's all. Differential fluid is fine. I read a few posts that said their JKs were sluggish but nothing worked. Working towards taking the Jeep out on a run and I want to make sure I get back home.
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Spark plugs? I’m at 81k on my 13 and changed them around 79k. They are supposed to be 100k plugs but mine looked pretty well used up to me.

IMG_7945.jpg
 
Did changing the plugs fix your issue? Yeah, the new car plugs are suppose to last 100k but yours look well used.
 
naysjp said:
Did changing the plugs fix your issue? Yeah, the new car plugs are suppose to last 100k but yours look well used.
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I had an uneven (not really rough, just not right) idle at first startup each day for a month or so. I can’t honestly say I noticed sluggishness beforehand, but it definitely feels a bit more responsive now. Also, according to my EVIC, I picked up about 1 MPG.

I’ve primarily used 87 octane and mostly from the likes of Shell, Chevron and Speedway stations. I was pretty surprised to see the wear just shy of 80k.
 
I just watched a video(not WOL) on how to change spark plugs and good Lord that's a lot of work just to get to them. I figured I would tackle it and it would take an hour, but that's almost how long it takes to take apart everything to get to them.
 
I had a similar issue, I installed a new coil pack, spark plugs, oil change/filter, and new air filter and there is a noticeable pep added.
 
naysjp said:
I just watched a video(not WOL) on how to change spark plugs and good Lord that's a lot of work just to get to them. I figured I would tackle it and it would take an hour, but that's almost how long it takes to take apart everything to get to them.
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If you allow the time and take your time, it’s not as bad as it seems. Don’t get me wrong, it sucks but if you don’t rush it gets done right. I think from setup to cleanup it was about 3-3.5 hours with some breaks here and there.

Here’s some more info in my build thread...

USMC Wrangler said:
It’s the Gearwrench brand on Amazon. https://smile.amazon.com/GearWrench-80546-8-Inch-6-Inch-Swivel/dp/B0014ZVSVK

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Yes. On the 3.6 you have to pull the upper intake to get to the driver’s side. I used the write up here on changing the oil cooler https://wayalife.com/showthread.php?t=42977 and the 1AAuto video on YouTube. You should take advantage and change the upper intake gaskets while you are in there. https://smile.amazon.com/Fel-Pro-MS-97205-Intake-Plenum/dp/B00QK4YY9S

I also used the Champion factory replacement spark plugs for the 3.6. https://smile.amazon.com/Champion-RER8ZWYCB4-Iridium-Replacement-Spark/dp/B0076GI5MQ



Thanks! Yes! No more slight stumble on cold start and definitely an improvement of throttle response. Of course I disconnected my battery for the swap, but Spider reads 18.1 MPG right now after a 20 mile test drive. I’m guessing that will drop. It showed 14.5 just before I disconnected the battery. We also know how accurate that is. [emoji849]
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I’m averaging 15.4 on the EVIC but haven’t bothered to manually calculate lately.

EDIT: I did not change any coil packs. Also, I understand it’s easier-ish to change the PCV while you have it torn apart for the plugs. I found that out after the fact. [emoji30]
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2013 JKU Sport S, named Spider

http://wayalife.com/showthread.php?26097-I-guess-it-s-the-quot-Super-Stocker-quot-build
 
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I asked the shop to replace mine while they are replacing a rocker and a camshaft. My jeep has 91K so I'm sure they will look just like yours...
 
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