Jeepney

So im right at 200k miles...within the last month my fuel pump and crankshaft sensor took a dump...what should i expect to go next...im wanting to do some preventive maintenance. I really hate no start surprises.

2001 jeep cherokee 4x4 sport ..all stock

tjwalker

Not unusual to see either of these components fail at this point. Mechanical stuff breaks....eventually.

As far as preventive maintenance?

*All fluids. Yup, all of them
*All cooling system components. Yup, all of them. You do NOT want an overheat, especially with the 0331 cylinder head that hates overheats
*Serpentine belt. I go 60k on mine
*Fresh spark plugs every 30k for the 00-01. I recommend NGK coppers, gapped to .035

Jeepney

..was also wondering of any other electronic device that might be due go bad..ie IAC or TPS perhaps...?

KJamesJR

The dreaded Crankshaft sensor... Mine is throwing the light at me as well. Still having the damnedest time trying to get the old one out.

tjwalker

IAC is pretty hardy, but if you've never cleaned it, I would....along with the throttle body. More on that below.

TPS is hit and miss. Some XJs eventually need replacement of this sensor, some go the lifetime of the vehicle. Usually it won't leave you stranded when they start to fail though, so I don't replace them preventively.
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The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

“Gently” wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled

Reinstall IAC and check idle quality

jebmccall

not to thread jack but would a dirty iac cause intermittent low idle rpm issues?

ZINGGG

I agree with everything, ESPECIALLY the cooling system. As for other electrical components, I'd say the upstream o2 sensor if you haven't already done that.

And yes, it can. Disconnect it from the throttle body (2 torx bit screws), splash some carb cleaner on it, scrub it with an old toothbrush, and put it back on and see what happens.