Hearing a *click* and intermittent idle.

No check engine light.

It will idle fine then I hear some sort of click and it'll drop a little lower and idle a little rougher, then 5 seconds later another *click* and it jumps back up to normal idle

One hint that may give someone insight is that it idles considerably smoother if my defroster/feet vent is turned on, that seems to be the only vent option that smooths it out.

Aside from that, I get some vibes at higher speeds and the steering wheel actually will shake a bit when i hit the breaks...Local mechanic told me my rotors are newer and in good shape and that these shakes and vibes will "smooth out" over time...does this make sense?

My apologies if this was a repost...I had no luck searching for my specific issue.

Thanks everyone

do you have the AC on?

What year Cherokee ?

Defrost engages the A/C compressor. The compressor clutch clicks on and off. The compressor takes enough power to make the idle drop. No problem.

Either the rotors are warped or not.

Warped rotors do not normally smooth out over time. Newness doesn't always help. I've had cheap aftermarket rotors warp on the first panic stop, and had other rotors last for over a hundred thousand miles.

You may get used to the shake, though, and since a little warp is more annoying than dangerous, it's up to you what you do about it.

Its a 2001 Cherokee.

To put it more simply...you are all correct in saying its the a/c compressor clicking on, however my issue is that I have a rough/low idle when the compressor ISNT clicked on...so if I were to turn off that defroster setting my idle would run more rough almost instantly.

ahibben said:

... my issue is that I have a rough/low idle when the compressor ISNT clicked on....

Click to expand...

Tune-up, and clean up.

Make sure your tune-up parts are fresh and clean the Throttle Body and Idle Air Controller. Add a can fuel injector cleaner to the next 2 gas tank fill-ups.

Yep, a tune-up sounds in order. First thing I check is the plugs. Most of the time when something goes wrong, I pull the plugs and if there is a small issue, they're red in spots. Seems really common with most issues. And I always use the Champion Copper plugs. I've never gotten close to a perfect idle with anything other than the Champions.
The rest as follows:
Seafoam if needed through intake.
Depending on the severity of oil leaks, an oil change ofter running 1/3 can of Seafoam in oil for at least 50 miles. (Wouldn't do this often.) w/Mopar oil filter.
ThrottleBody cleaning with toothbrush and carb cleaner. (I take mine off and do it on a table. Careful with the sensors and take them off if possible.)
Check vacuum lines and grounds. It's boring but can help.
Check and repair any intake/exhaust manifold leaks and/or cracks.
Check injectors for leaks or connection issues. (Do a search for Dodge Neon injector swaps. For efficiencies sake, I think it's worth the trip to the junk yard and a couple bucks.)
Air filter.
Coil + plug wires.

Thats my main efficiency to-do/check list. Other than that, I've tried 6 muffler combinations and found that no muffler has been best in my experiences. Living in Arkansas, there's no smog worries.

If you value being able to whisper with the windows up, or having cognitive thought processes, I wouldn't recommend it.

And make friends with any cop within the first 15 seconds of being pulled over, or you'll be fighting a ticket.

Sent from my ADR6350 using Tapatalk

Use NGK plugs, not Champion.

Talyn said:

Use NGK plugs, not Champion.

Click to expand...

Care to mention why? NGK is a good plug, but I've consistently noticed a better idle in two stock cherokees over the course of 7 years, and have made many comparisons between the two plugs on both.

Not to mention that the majority of other 4.0 owners have had similiar experiences.

Sent from my ADR6350 using Tapatalk

Its a stock plug and it works better than the Champions in the 97+, especially the 00+ with the waste spark system.

1999 and older XJ's seem to run best on plain Champion plugs or plain NGK plugs. 2000-01 seem to run better on AutoLite APP-985. That has been my experience with owning ( 5 ) 97-01 Cherokees.

I see no reason to use Sea-Foam or mystery additives anywhere but the gas tank. Regular oil changes will keep the engine clean.

Check the lines at the fuel vapor canister. There is a clicking sound when it is operating and if one of the vacuum lines has holed, it could contribute to rough running.