2007 Jerking/surging at 1500 rpm

tsn6186

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Jun 28, 2022
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Rising Fawn, Ga
I have a 2007 Jeep Wrangler with approx 92000 miles. a couple of weeks ago the check engine light came on and I scanned. The code was P0301 misfire on cylinder one, but the Jeep was not showing any signs of a problems, no rough idol, no shaking, nothing. Code was cleared. Check engine light came back on a couple of days later and started flashing and dinging, and jerking/surging hard while around 1500 rpm (45-50 mph) and while under load going up a hill, same code. Check spark plugs and wires and seemed okay, they had been changed about a year ago (April 2021). Changed the ignition coil and rescanned, had 2 codes then, P0301 & P0303. Replaced the entire exhaust system, new cats, new 02 sensors. Codes were gone, rescanned and nothing was detected wrong with vehicle all seems good, running smooth. Driving to check everything out about 15 miles down a mountain and all seems fine, while driving back home up the mountain started to feel a slight jerking/surge. When you go into passing gear or drop down to low 2 it will stop, but once you go back to approx 1500 rpm it will start again under load going up a hill. I will add that when we removed the old exhaust, it seemed like there was alot of water in the pipes, more than we thought should had been, maybe just me over thinking things. I have an appointment with the dealer next week, but we are still trying to self diagnose. Any suggestions, any help is greatly appreciated. Automatic transmission, running 35's, with 3" lift. Thanks again..
 
You could have some water in your fuel have you tried adding some Heet?

Did you recalibrate your speedometer after putting the 35's on?

Are you still running the stock gears? What gears in it now?
 
You could have some water in your fuel have you tried adding some Heet?

Did you recalibrate your speedometer after putting the 35's on?

Are you still running the stock gears? What gears in it now?
I have not tried Heet, We did think about water when we notice the water in the exhaust. I will try that. I have not recalibrated speedometer. Didn't' even know that was a thing. How do you do that? Stock gears, I believe the 2007 has 4:10, but I'm not positive. I read on another forum that that its okay to run 35's on stock gears, but I am a novice at best. I get about 14-15 mpg and have owned the Jeep for over a year, with no problems until recently.
 
I have not tried Heet, We did think about water when we notice the water in the exhaust. I will try that. I have not recalibrated speedometer. Didn't' even know that was a thing. How do you do that? Stock gears, I believe the 2007 has 4:10, but I'm not positive. I read on another forum that that its okay to run 35's on stock gears, but I am a novice at best. I get about 14-15 mpg and have owned the Jeep for over a year, with no problems until recently.

Most will use JScan and a dongle like this. Your transmission shift points are not where they are supposed to be because of the taller tires. If you was to check your Speedometer with a GPS you'd see the speed was off on your speedometer.

 
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Most will use JScan and a dongle like this. Your transmission shift points are not where they are supposed to be because of the taller tires. If you was to check your Speedometer with a GPS you'd see the speed was off on your speedometer.

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It would just now start causing a problem? I have had the 35's on for about a year and have not had any issues with the jerking/surging until a couple of weeks ago.
 
It would just now start causing a problem? I have had the 35's on for about a year and have not had any issues with the jerking/surging until a couple of weeks ago.

It could be something else along with the speedometer out of calibration but on a automatic trans it has to be reading correctly for the trans to shift correctly. If it was mine i'd calibrate the speedometer and then see if it still does it and go from there.
 
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Okay thank you for the advice and info, at least I have something else to try.

Maybe a local tire store would recalibrate your Speedometer. But the JScan will allow you to read Codes and make a few programming changes on the Jeep also.
 
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Maybe a local tire store would recalibrate your Speedometer. But the JScan will allow you to read Codes and make a few programming changes on the Jeep also.
I got a bottle of Heet to try and I going to also try Pure gas along with the Heet. I also ordered the iCar Pro scanner for the JScan app, to recalibrate my speedometer. So we'll see if any of this works before I take to the dealer next week. Thanks again for the advice and info.I'll follow up on the results
 
FOLLOW UP.....Replaced the exhaust systems from the manifold, new cats, 4 new 02 sensors, new ignition coil, new PCV value. Recalibrated my speedometer with the iCar Pro scanner for the Jscan app. No problems or codes detected, no misfire in cylinder 1 & 3 all is good. Fuel milage actually got better, transmission shifted better/smoother. GREAT!!!!.
Oh but wait.....today the surging was back, still around 1500-1600 rpm. Rescanned when I got home and NOW it is misfiring in cylinder 6, P0306. NO check engine light. Any suggestions on where to go from here? SO FRUSTRATING!!!!!