iggy

sounds like a spark plug went bad and you are getting a miss fire had the same problem with my 99 dodge dakota last year. i would start running rough for no reason. i found the dieing plug and the shake was gone

98jeepboy

I have a 09, with less then 9k on the clock. Mine started at 300 miles. It is a daily driver at the moment so I have it happen alot to me. Go through a drive through and sit for a bit. It happens alot then.

Since I have alot of free time sitting in the drive through, I did alot of testing.
Does it happen Then?
A/C On:Yes
A/C Off: Yes
Headlights On: Yes
Headlights Off: Yes
Radio On: Yes
Radio Off: Yes
Rolling Pwr Window up or down: Yes. Note: bogged the motor down more.
Heat On: Yes
Heat Off: Yes
Faced Up Hill: Yes
Faced Down Hill: Yes
Flat Ground: Yes
Cooling Fan On: Yes
Cooling Fan Off: Yes
Engine Cold: Yes
Engine Hot: Yes


What cause it to stop.
Pump the brake a few times: Idled up
Tap the gas: Stumbled and Reved up

I run 87 gas. I have ran 5% to 10% E85 depending on where you buy gas at. That has no bearing on it. Still happens no matter the content.

I have thought about spark knock but if it was that, you would have it more then just once and a while. Drive an oldsmobile from the 80's with a V8 put 87 in it and youll know what spark knock is.

Also if you watch your gauges when it happens the RPM drop never shows. I have had it happen in Neutral too but you really cant feel it.

I am running the same Cone air filer I was on my 07, an have tried the stock box with less then 100 miles on filter. MOunts are brand new, if it was this it would be a constant problem and not change unless you change the angle of the jeep.

An the idle is set to about 550 to 600 on the JK. Even though it show about 700, on the scan tool mine was barely maken 600.

There was an article in a mag that said car company's where cutting idle RPM's to save on gas while sitting. I am sorry but 750 will not burn much more then 600. Not a great difference.

My 2cents is get rid of the Fawking drive by wire. So people can set there idle for winch and other need for elec and pump power.

IcyFridge

I have the same issue too. It happened to me only twice so far in the past 5000 miles. No idea what causes it but it scared the heck out of me.

mattyhfd

it really annoys me!

jeepoholic

Do you buy your fuel from the same place every time. If so it may have water in the fuel. It sounds like something in the fuel system to me.
Good luck.

98jeepboy

With mine, I can fill up anywhere. I just drove it and had it do it to me. It is kinda getting a normal thing, but I will soon have it in for it to be looked at. I think it is a bad line of code for the computer.

mattyhfd

x2 , i dont go to the same place really, im not that picky with my fuel as long as the guy pumping it knows what im saying and/or the place isnt a crap hole!