Engine Sputtering around 1500RPM?

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Fierdon

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I haven't had my Liberty for very long and have been noticing that there's hesitation under light acceleration around 1500rpms and usually between 30mph-50mph. Once I'm over 2000RPM and 50mph, it goes away and no CEL or anything comes on. It also seems to not do it under heavy acceleration. I'm not extrememly mechanically inclined, so I'm not sure what it could be. If it is possibly transmission or something with fuel/ignition or maybe just a quirk the KJ has. Anyone have any idea what I could start looking at?
 

ltd02

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How many miles on your KJ? What's the service history? Have you checked the plugs? The stock plugs are copper core and, although best for the vehicle, only last for about 25-30k. I'd start there and let us know what you find.
 

Fierdon

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How many miles on your KJ? What's the service history? Have you checked the plugs? The stock plugs are copper core and, although best for the vehicle, only last for about 25-30k. I'd start there and let us know what you find.

It has just shy of 97k miles on it now. I'm not sure about maintenance hisotry aside from what was on CarFax. It's in extremely good shape for its age. Had to replace the radiator shortly after I got it because of a small crack. I just bought it with about 95k miles on it about two months ago. I'll buy a set of spark plugs and change them out. Hopefully that will be all.
 

Myke

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It has just shy of 97k miles on it now. I'm not sure about maintenance hisotry aside from what was on CarFax. It's in extremely good shape for its age. Had to replace the radiator shortly after I got it because of a small crack. I just bought it with about 95k miles on it about two months ago. I'll buy a set of spark plugs and change them out. Hopefully that will be all.

If the replacement radiator isn't Mopar I would keep an eye on it and expect it to crack again within a year or two. Also if you didn't have the dealer do it I would verify what coolant was put in. The liberty uses HOAT coolant and it can not be mixed with OAT coolant. HOAT coolant is usually orange vs the green of OAT. You can buy it from the Dealer or some auto parts stores carry Zerex G-O5 (hoat coolant).
 

Juggar

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My 2007 had what seemed to be the stock plugs with 96k miles on them.....

Suffice to say it ran much better when I changed the plugs. The old plugs were HEAVILY worn, like im surprised it ran as well as it did. Gap was huge.

First time in my life ive actually seen used up spark plugs.

Change the plugs and I bet it will be much better.
 

LibertyTC

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Refer to the recommended plugs from the under the hood sticker & gap.
61993[/ATTACH]"]
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The ignition coils on the KJ fire those plugs hot, so 30k miles is as long as I will allow the gaps to be eaten.
Jeep will "run" better using these..
61995[/ATTACH]"]
You must be registered for see images attach

It's a good place to start, new are filter, clean the IAC-throttle body ports too. :gr_grin:
 

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Fierdon

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If the replacement radiator isn't Mopar I would keep an eye on it and expect it to crack again within a year or two. Also if you didn't have the dealer do it I would verify what coolant was put in. The liberty uses HOAT coolant and it can not be mixed with OAT coolant. HOAT coolant is usually orange vs the green of OAT. You can buy it from the Dealer or some auto parts stores carry Zerex G-O5 (hoat coolant).

I had a local high-quality mechanic shop do the replacement. They said they don't use aftermarket and only use OEM parts. I'll have to check to see if the coolant is orange or green, not sure what they used. Good thing is, the radiator has a lifetime warranty and they have a two year warranty on their work. They are a little bit more expensive than other mechanics around me, but they don't use aftermarket and they always get my vehicles back to me very quick. Been using them for years.

My 2007 had what seemed to be the stock plugs with 96k miles on them.....

Suffice to say it ran much better when I changed the plugs. The old plugs were HEAVILY worn, like im surprised it ran as well as it did. Gap was huge.

First time in my life ive actually seen used up spark plugs.

Change the plugs and I bet it will be much better.

That's probably where I should start, I imagine if there were no issues with anything, they were never changed. The sputtering isn't bad, but it is noticeable.

Refer to the recommended plugs from the under the hood sticker & gap.
61997[/ATTACH]"]
You must be registered for see images attach

The ignition coils on the KJ fire those plugs hot, so 30k miles is as long as I will allow the gaps to be eaten.
Jeep will "run" better using these..
61999[/ATTACH]"]
You must be registered for see images attach

It's a good place to start, new are filter, clean the IAC-throttle body ports too. :gr_grin:

Thank you for that info! I was going to go search what was needed as far as plug gap and all. Should I only use the copper ones? RockAuto.com has higher quality ones that aren't much more expensive, but if I should stick to the base NGK, then I will.
 

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Leeann

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Only use copper. That’s what the engine was designed for.
 
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