Having a few issues with the way my TJ is running

Joseph

Joseph

TJ Enthusiast
Joined
Aug 20, 2018
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392
Location
North Jersey
so the jeeps been acting weird lately. i show no codes on the dash.
1. today on the highway doing about 70, the jeep bucked like it dropped lower in rpm then went back up. i noticed this too when driving up a hill after this. i wasn’t really watching the rpm during these moments but that’s how it felt. doesn’t feel like a slip though.

2. the jeeps been taking a few seconds to crank over, although it does turn over on the first try. it doesn’t do this when it’s already warm, and didn’t do this until about last week.

3. the idle isn’t too rough, but it isn’t great. it sits around 550-600. a handful of times when i start it since owning it id start it, it’d run really rough, then go back to normal after a few seconds

4. a little slow on the acceleration. feels like it’s dogging a bit and i feel like i’m consuming more gas, but i haven’t done any actual mpg calculations.

5. don’t know if this is related or not but i read it may be. anything over 3/4 of a tank my gauge will read empty until i hit half a tank. once it’s a bit below a quarter tank, it’s hardly accurate and changes reading frequently

any suggestions? or a route to go first. i know the typical tune up clean the IAC or the CPS but i was wondering my best route to check out first with the symptoms i mentioned.
 
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That OBD port is the great thing about modern vehicles. It takes a lot of guesswork out of the problem.
 
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For what it’s worth, the behavior you’re describing is exactly what I was dealing with before swapping out the spark plugs.

Cheap and easy, so no reason not to try that.


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I mentioned no codes on the dash guys, I keep a handy code reader in my car so if that was the case I probably wouldn’t be here haha
 
I have two suggestions:
  1. Clean the IAC of course.

  2. Keep driving it. It's going to throw a code at some point (guaranteed), and the more you can get it to keep making the symptoms, the more likely it's going to throw that code.
I hate throwing money at things blindly, because it's a huge waste of time and money. The codes are going to be they key to at least being pointed in the right direction. At the moment, this really could be a slew of things. I'd hate to just throw money at it without even having an idea.
 
Chris said:
I have two suggestions:
  1. Clean the IAC of course.

  2. Keep driving it. It's going to throw a code at some point (guaranteed), and the more you can get it to keep making the symptoms, the more likely it's going to throw that code.
I hate throwing money at things blindly, because it's a huge waste of time and money. The codes are going to be they key to at least being pointed in the right direction. At the moment, this really could be a slew of things. I'd hate to just throw money at it without even having an idea.
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Well with the information gathered so far I might give the sparkplugs a go. Cleaning the IAC is free so I'll do that too. It hasn't thrown a code yet, but today while driving I was paying a little attention in traffic and the RPMs dropped really hard and went back up quickly. It's doing it probably every 20-30 miles I'd say. Hasn't stalled yet. This mornings start up took a few seconds to turn over again.
 
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Well low and behold the Jeep stalled out 3 times on my 25 mile commute. It threw P0320 but cleared once I restarted the car. I went and picked up a mopar crank sensor anyway for $125 with a nice discount. Let’s hope this fixes my issue If not you guys will be hearing from me again haha
 
Joseph said:
Well low and behold the Jeep stalled out 3 times on my 25 mile commute. It threw P0320 but cleared once I restarted the car. I went and picked up a mopar crank sensor anyway for $125 with a nice discount. Let’s hope this fixes my issue If not you guys will be hearing from me again haha
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Thanks for the update! I knew it would throw a code eventually, which is what you want it to do. I hate trying to troubleshoot blindly. It usually ends up being expensive!
 
Chris said:
Thanks for the update! I knew it would throw a code eventually, which is what you want it to do. I hate trying to troubleshoot blindly. It usually ends up being expensive!
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Yeah of course, I just read your write up on how to do it. Figuring out if I can borrow my buddy’s garage tonight or if I’ll just have to do it in the morning. I’ll let everyone know how it works out
 
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Joseph said:
Yeah of course, I just read your write up on how to do it. Figuring out if I can borrow my buddy’s garage tonight or if I’ll just have to do it in the morning. I’ll let everyone know how it works out
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Awesome, I look forward to it. Hopefully this resolves your issue.
 
Chris said:
Awesome, I look forward to it. Hopefully this resolves your issue.
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Decided to tackle it before the morning. Took me about 40 mins with most of the time coming from trying route the thing the right way and figure out which extension would work best.
I didn't get it to click together as hard as I tried (I'll check again in the morning) but I started it up and it rumbled for a few seconds and got smooth. Idle was a lot higher than usual too and it cranked right over. I assume that's the computer getting used to the new sensor the rumbling for a second? I did a camshaft sensor on one of my BMWs and it did the same thing for a bit.
I also didn't have access to a torque wrench so I just made it nice and snug. P0320 still appeared on my dash when I checked with the odometer, although I only ran the Jeep for a minute or so. My code reader read nothing to clear.
 
Joseph said:
Decided to tackle it before the morning. Took me about 40 mins with most of the time coming from trying route the thing the right way and figure out which extension would work best.
I didn't get it to click together as hard as I tried (I'll check again in the morning) but I started it up and it rumbled for a few seconds and got smooth. Idle was a lot higher than usual too and it cranked right over. I assume that's the computer getting used to the new sensor the rumbling for a second? I did a camshaft sensor on one of my BMWs and it did the same thing for a bit.
I also didn't have access to a torque wrench so I just made it nice and snug. P0320 still appeared on my dash when I checked with the odometer, although I only ran the Jeep for a minute or so. My code reader read nothing to clear.
Click to expand...

Try disconnecting the battery for 10 minutes. That often times will do the trick.
 
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