Jeep KK rough idle

[Ghostly7287]

Hello and this is my first post here, I have posted at other jeep forms and searched forever but no answers.

So I own a 2008 Jeep Liberty limited 4x4 3.7 it has exactly 115,000 miles extremely clean garage kept and has never missed regular maintenance once.

So it has a rough idle that chooses when it wants to idle rough, the easiest way to explain its almost like a quiver or a light miss fire. So it will idle perfect for days or weeks then just act up for days or weeks. It will do it in any gear anytime it chooses.

i have recently changed the plugs, yes gapped correctly, I have changed the coil overs, cleaned the throttle position sensor butterfly flap because it’s electronic, so no IAC on the jeep KK. I’ve changed the PCV, Air temperature sensor because there’s no mass airflow sensor, new air filter and countless other things. I even bought and installed all 6 new fuel injectors and I will admit it’s extremely quiet now with the new injectors and I gained 4 MPG now I’m around 14mpg lol

I tried everything I don’t know what else it could be I’m the type to do preventative maintenance because I’m afraid of something very expensive breaking which I can’t afford and this is my only car. Any info would help thanks in advance.

 

[gpell]

It seems to me if you were getting 10 mpg with this rig (unless you are pulling a 5,000 pound trailer 24/7) there was an issue before all the part change outs. Do you have a code
reader that pulls live data? It is hard to say, could be fuel related-try running dry gas or sea-foam next time you fill you up.

 

[lfhoward]

Is your Jeep lifted and running larger tires? MPG sounds like mine!

 

[LibertyTC]

Ya I know the larger tires, lifted feeling all right..

 

[Ghostly7287]

ignore this I sent it wrong lol

 

[Ghostly7287]

It seems to me if you were getting 10 mpg with this rig (unless you are pulling a 5,000 pound trailer 24/7) there was an issue before all the part change outs. Do you have a code
reader that pulls live data? It is hard to say, could be fuel related-try running dry gas or sea-foam next time you fill you up.

Never hauled anything has just been a family ride. I’ve always ran sea foam or Techron after a oil change. I’ve even looked for stored codes and none. I do have a code reader with live data but I’m not a professional when reading everything on it as far as the live data goes anything in specific should be looking for?

 

[Ghostly7287]

Is your Jeep lifted and running larger tires? MPG sounds like mine!

Just the stock 18” tires they are not off-road I decided to spend extra to get the best Pirelli’s because it mainly stays on the pavement it’s my back and trough to work and my family car. I do know it’s the shape of a brick and and weighs more then a semi lol

 

[John P.]

Not sure how much this helps, but when I run live data these are what I check. I check fuel trims bank 1 and bank 2 should be 2.5 or less closer to zero the better things are operating however 5 give or take is acceptable range. O2 bank 1 once warmed up should give you voltage fluctuations from .5 to 1 back and forth bank 2 similar pattern, a graphing scan tool helps with O2 readings. Engine temp, and transmission temp. Once you learn your live data, you can catch issues before they ever trip a CEL. I have a 2011 and took a road trip, I have a tool that links with my phone. I noticed my fuel trims were off, adding 7% to subtracting up to 3% cruising around 65mph. I bought and changed spark plugs because this was indicating an ignition issue. Sure enough the plugs were at end of life, .7 on my gap gauge. Gapped and installed new plugs and the Jeep is happy again.