14' JKU w/ 89K miles seems sluggish

naysjp

Member
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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USMC Wrangler

New member
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.

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
 

naysjp

Member
Did changing the plugs fix your issue? Yeah, the new car plugs are suppose to last 100k but yours look well used.
 

USMC Wrangler

New member
Did changing the plugs fix your issue? Yeah, the new car plugs are suppose to last 100k but yours look well used.

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.
 

naysjp

Member
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.
 

tonytony9

New member
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.
 

USMC Wrangler

New member
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.

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...

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

View attachment 329430

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]

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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jorgelrod

Hooked
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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