Hey guys. I'm continuing to renew my 1997 xj 4.0 auto every place I can. Already done o2s, lift, tires, motor mounts, cap rotor plugs and wires, air filter, and some oher things. I'm wondering if it's necessary as routine maintenance to replace things like map sensor, iac valve and tps sensor. I do have a minor rough idle. Are these parts that can wear and I should change either way? Or is worthless to swap them out without knowing one is bad? I have the extra money to do so, and I want this jeep completely renewed as I plan to own it forever, and make it outlive me!

 

You might want to run a can of BG44 in your gas tank just to clean up your injectors. Might even help with your rough idle.

 

I just filled up. I'll get one tonight. I just read a post a few before mine about the guy who changed his tps for the heck of it and it ran a ton better, will probably do that too.

 

Your throttle body/valve and IAC ,I would just start with a clean.
If not replaced in the past, keep a spare CPS (OEM preferred) handy; you will need it at some point. An OEM TPS apparently gets harder to find, so keep an eye open for it...'preventative buying' to facilitate preventative maintenance

For longevity of your trans: replace your ATF and keep it nice and red.
Regular oil changes and good filters are best thing to do to keep your engine going
Make sure your cooling system is uptodate

Other than that: enjoy and repair as you go.

 

^^^X1

 

Crown is oem for the most part isn't it?

 

I think they sell aftermarket stuff, not true OEM.

 

Decent quality aftermarket.

 

What brand of spark plugs did you use?


Courtesy of TJWalker:
--------------------------------------------------------------------
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

 

I just installed new bosch single prongs. I've read so many mixed reviews on plugs that I went with bosch. Here's the thing......after I replaced both o2 sensors it started doing it. I put in some Lucas injector cleaner the other night, and although I haven't paid much attention, the rough idle has not jumped out at me since, but then again, I haven't been paying attention as I've been mostly adjusting my audio all the time due to my new stereo setup, ( all while driving bad I know)

 

NGK plugs and you can't go wrong. Next time maybe.

 

My 98 loves champion coppers. If I put anything else in, it feels much rougher (but it could be in my mind).

Also:
* Swap ALL FLUIDS (power steering and brake fluid as well!)
* Change any leaking gaskets or o-rings
* Remove the Oil Pressure sending unit, and clean it thoroughly. Take a pipe cleaner, and clean out the passage that it connects to and see if there is any gunk in there (helps give you a more accurate oil pressure reading).
* Make sure you grease all the chassis zerk grease fittings as well
* Clean ALL critical electrical connections (especially charging circuit connections)

 

I don't know where you read all the mixed reviews but I doubt if you got them from the three major XJ forums. I'll save you the trouble of researching again and just say that the general consensus for the Jeep 4.0L engine is:

Champion Copper: Good
NGK: Good
E3: Bad
Autolite: Bad
AC Delco: Bad
Bosch: Bad

I've tried several and there is no doubt in my mind that my 4.0 likes the NGK V-Power plugs the best. I was able to exchange one plug brand for NGK V-Power plugs at O'Reilly's.

Do everything suggested and you should get yours running good. I don't know if it's even possible to get the engines running smooth as glass at idle.

 

Agreed on the idle. My jeep guy said it's a straight six with 210k on it, it's kinda the nature of the beast. I've already done this:
4.5" rc lift replacing all shocks and front and rear steel braided brake lines as well. My rear drums were adjusted while in there.
Oil change
Cap, rotor, plugs, wires
New oil pressure sending unit
New alternator
New o2 sensors
New engine mounts
Have new track bar (bushings are bad) needs to be installed
Have transmission filter ands seal, needs to be changed along with fluid
New tires
New from sway bar bushings
Alignment
Flushed heat core....omg it was so clogged!
Ordering battery cables from 5-90 this week
4:56 gear master kit is ordered
New tps, iac valve, and fan shroud order
Replaced some ****ty coolant hose clamps
Need new exhaust as my cat is rattling from the inside lol

I think I've got a good start. I regret putting bosch plugs in, I'll probably change them out since it's cheap enough.

 

If your installing 4.56 gears (I hope you bought a package deal) I just did the same changing to 4.56's. The complete package with master install kits under $500.

While your doing the gear change if budget permits, is the best time to install lockers front and rear the labor is already done. I'm doing Detroit Lockers in my D30/Chry 8.25 29 spline.