Hey guys, I know theres been some discussion about this issue, but I havent found one quite like mine. My Jeep started to buck at around 70 mph on the highway, and it wouldnt start right away, it seemed like it did it when it was running for a little while. It would just randomly start bucking and sometimes it would go a little ways without bucking and then it would start again and constantly do it. Its winter now in Michigan, and since the cold hit, its started the bucking at around 55 mph...I cant figure it out. Im not extremely gifted with vehicles and everything, but I know basics.

Just last night I was hanging with my buddies going about 55mph, and the Jeep's rpm's went way down, and it felt like I lost all power (but it was still running) and it wouldnt let my go over 45 mph. I slowed down and stopped on the side of the road, and the entire jeep was shaking (on the verge of stalling out). I turned the Jeep off, and turned it back on and it was completly fine...any suggestions?

Thanks in advance for your responses. I hope to fix whatever the issues are, so i can have my Jeep back! :P On a side note, I think I need to stick to offroading, its only on the black top that I have the issues! Thanks!

 

Mine did this and it turned out to be the fuel pump.

 

1. Any check engine light? Even if the answer is no, it might be a good idea to scan the computer for any stored codes for clues here.

2. I agree with Mech17 that fuel delivery should be ruled in or out early in the process. Must be done with a gauge. For a 2000, you should have 49 psi, plus or minus 5 psi

3. Upstream oxygen sensor, map sensor, cam sensor are also possibilities. Even crank sensor. They can all be tested, but unless you test when symptomatic, test data will most likely be within spec. Of the sensors, I'd be most suspect of the oxygen sensors.

 

Thanks for the replies guys. I will definetely start checking these things out in the next couple of days. It does have the check engine light on, and I plan on going to autozone tomorrow to get the codes.

I am personally leaning towards the fuel pump, but I wanted to see what others thought too. Could it just be a fuel filter issue? I guess if I change the fuel filter I should change the fuel pump because there both inside the tank.

That reminds me, when you turn just the battery on, you do hear the fuel pumps humm. But also when im going slower, and I let up on the gas pedal I hear some strange noises coming from the fuel pump, kinda liking humming, but a little different..its very hard to explain...but it doesnt sound like it should be making the noise!
Again, thanks for the quick replies. I will post the check engine code tomorrow.

 

Never ever ignore the check engine light.

The fact that you have a check engine light and symptoms is most likely not a coincidence!

Post the code(s) here for comment. The codes are absolutely invaluable to understanding driveability issues on your XJ. The OBD system isn't perfect, but it is awfully darn good at pointing you in the right direction (to the right circuit).

 

Vacuum leak?

 

Hey guys, went to Autozone today to run the codes. I got four codes.

P0353: ignition coil primary circuit condition number 3 (I got three of these codes, for ignition coil 1, 2, and 3) Would these cause the problems? The person from autozone didnt really know. Number one reason on these are the ignition coil is defective.

The last code that I got was P1391: ECM detected the actual CMP position disagreed with the expected CMP level. Probable Cause: Timing belt or chain stretched or jumped. or Defective CMP sensor.

Thanks for the help guys.

 

A going coil could definitely cause your problems. And idk about that other issue. I would think if the chain had slipped or whatever you'd have much more bigger problems.

 

Or a defective CMP sensor........

 

P1391 is intermittent loss of either the crankshaft position sensor OR the camshaft position sensor.

You could have an issue with the "synchronization" of the camshaft sensor. I know I've seen this issue before a couple of times and I think it had similar codes to what you are seeing. It is not uncommon on the 00-01.

Below are two links you must read and it certainly is worth checking this possibility out; all you need is a "toothpick"! The cam sensor can also be electrically tested with a manual and a meter and along with synchronization, I'd recommend testing of that component.

Both of these look very similar to the codes/symptoms that you are seeing.

http://www.askamechanic.info/askamec...nt/view/55/47/

http://www.jeepforum.com/forum/f11/h...ensor-1145301/

 

I'd imagine that a bad camshaft sensor would certainly cause ignition timing to screw up

 

which could also cause coil problems to throw those codes

 

I dealt with this problem for months and quit caring after i replaced everything p1391 could be caused by my light would turn on and turn off. I replaced the Crank position sensor with an after market sensor and sure it helped for about 30 miles and it was back just different only missed at idle. Replaced my Crank position sensor again with and oem and guess what, It solved all my problems, not saying its your problem but if you do go ahead and replace your ckp, do use Original equipment.

 

Hey guys, appreciate all the help. I just wanted to let you know that it was the camshaft sensor. Replaced it and the Jeep is running like it should! I have my baby back!

 

Good to hear, i know the feeling, everytime mine breaks on me and i have to drive the wifes civic i want to