Hoping to get some help with a weird problem I’ve been having.

For quite a while now I’ve been having this issue with driving. At around 60-70 mph I get this “hiccup” sensation where it feels like I’m driving over a speed bump, it’s almost as if it stalls for half a second and then picks back up. It’s very inconsistent, sometimes only happening once, then again at least three to four times. My RPM’s stay consistent, no jumping. My speedometer remains the same, none of my other gauges are altered by this. Speeds from 0-50 have no issue, drives great. Speeds from 70+ are alright, has the occasional hiccup but not like the 60-70 range.

I’ve replaced the CPS, 6 new fuel injectors, did a fuel rail pressure test multiple times, installed a fuel rail heat shield. Checked the transfer case fluid, came back clean. Transmission fluid looks good. A few codes came up while diagnosing the issue:
P0320
P1391
P0118

looking to hopefully get some new insight into the issue, otherwise I might have to take it in and see what the issue is. Thanks!

 

Hello this is o e of my exact symptom. 1999 cherokee xj. Bucking at 70 km. Same code in common po118 is one of my code that matches yours. I did replace my temperature sensor but same issue.

 

I did get a p0700 at one point. Some one on this forum I saw got it also with the same issue and replaced the VSS but no change. I am wondering if it's the coolant sensor?

 

The difference is my rmp jumps and idles low.

 

Check your crankshaft position sensor. Those codes, especially P0320, point directly to it causing that exact hiccup at higher speeds. It's a classic symptom on the 4.0L. Make sure you get a good quality one, not a cheap parts store brand.

 

I replaced mines same issues. I will try an ngk. Hope it works. I get stuttering at 70km
also have low unsteady idel.

 

You mentioned you replaced the CPS, was that the crankshaft position sensor or the camshaft position sensor?
I would look towards the distributor for wear and tear of the distributor cap, camshaft position sensor, the wiring to that sensor, your spark plug wires for rub wear or deterioration and also your coil. With the coil, remove it to inspect it for hairline cracks that could be shorting it out...

 

Thanks for your reply Bruce.
I replaced the Crank position sensor, TPS, plugs, wires, distributor cap and rota, both 02 sensors, MAF sensor, new throttle body, coolant sensor.
I will look at the camshaft position sensor, it a 1999 xj. Will check the coils.
Thanks again for your time.

 

are you the thread starter of this thread.... if not, please start your own thread related to your issues.

 

On my XJ I went with

NGK/NTK Crankshaft Position Sensor EH0248 (73276)

No isues yet

 

Thanks for your reply sir. Yes I reordered an NTK.

 

Thank you to everyone that has responded with your solutions, I really appreciate it! I went ahead and ordered a new crankshaft position sensor, I'm still getting the same code P0320 so maybe this higher quality one will help me out! While I wait for that to arrive I'll go ahead and inspect the distributor cap, camshaft position sensor and all the wiring, spark plugs, etc... I'm sure there's some electrical gremlin in there causing all sorts of issues. Looking forward to letting you all know how it goes!

 

We can call this a public service reminder if you like.

When checking distributor caps and rotors do not forget to check the distributor shaft.

When pressed back and forth or side to side in any direction there should be no deflection. It's supposed to spin only, not move around.

If there is any noticeable slop/play/radial movement/deflection, either the shaft or distributor housing are worn.

In addition to distributing the spark, our distributors let the computer know when to spray the fuel injectors.

One of my Jeeps came to me with a seriously worn distributor but it still ran. Ran like crap. Replacement was like $65 then it purred like a kitten.