Ok, so I am getting ready to lift my xj, and do a rear disc brake conversion, along with some other fixes (rear main seal, ball joints, axle seals, dif fluid, etc) and I have 2 problems that I haven't found the problem to yet.

#1 cruise control - The light will come on, but will not stay on. At first I thought clock spring since the steering wheel is always moving a little, but the horn works fine. Also when I get it to stay on for couple of seconds, I hit the set button and it turns right off. I have checked the vacuum line all the way to the intake manifold, and all is ok, but it continues past the CC unit and into the front of the jeep. Not a huge problem, but will be doing some road trips in this and my foot would greatly appreciate it working.

#2 rough idle at hot start - cold start is fine. Go into the store or whatever for more than a half hour, fine. Stop at a gas station or something for a couple of minutes, starts up rough, then clears right up when I get into Drive and start moving. Thought fuel filter, or pump, but this seems like a fuel pressure check valve or maybe injector issue? I checked all the plugs and the gap, they all look fairly new.

Just over 200k on this baby, but I can tell it was well taken care of for the most part. I don't mind putting some $$ into preventative maintenance but don't want to spend $$ on the wrong fix when it could go towards my other goodies for the lift/build.

Any suggestions are appreciated.

 

Year/engine?

 

Sorry.... 2000, sport 4.0L

 

For a 2000, your #2 is most likely "heat soak". Quite common on the 00-01. Below is the factory TSB for wrapping the #3 fuel injector, but from everything I've seen, this only helps on very mild cases of heat soak.

Others have installed a timer on the e-fan that keeps the fan on for a preset time after you turn off the engine. Some have cut "louvers" into their hood. Search and you'll find multiple threads.

Also for a 2000, be sure that your entire cooling system is up-to-snuff. You do NOT want to overheat the engine, which is a surefire recipe for cracking your factory 0331 cylinder head, which has a defect between cylinders 3-4. Keep a close eye on the level of coolant in the reservoir, as "the #1 symptom of a cracked 0331 head is unexplained coolant loss. I recommend checking your reservoir level at least weekly; takes all of 1 minute.

Enjoy your XJ!

-------------------------------------------------------------------------------------------
TSB 1803103 - 4.0L ROUGH ENGINE IDLE AFTER RESTART FOLLOWING A HOT SOAK
Date: 09/05/03 (supercedes 1802702 dated 09/06/02)
Model Year(s): 1999-2004

Description: NOTE: This bulletin applies to vehicles equipped with a 4.0L engine. This bulletin involves the installation of a fuel injector insulator sleeve.

Details: Customers may describe a 20 to 30 second rough idle following the restart of a heat soaked engine. This condition may be most noticeable when the engine is restarted following a prior 10 to 20 minute heat soak in hot ambient conditions of approximately 32 C (90ºF) or higher. This condition may be consistent with short city stop-and-go driving trips and can be aggravated by the use of fuel with a high ethanol content. Depending upon various conditions a MIL may occur due to DTC P0303 - Cylinder #3 Misfire.

This condition may be caused by heat from the exhaust manifold that following engine shut down migrates to the area around injector #3 and causes fuel vapor to form within the injector. This in turn may cause a momentary misfire of cylinder #3 until the fuel vapor is cleared of injector #3. The insulator sleeve lowers the injector #3 temperature to a point below which the fuel will not normally vaporize.

If vehicle exhibits a rough idle, and if a misfire of cylinder #3 is observed following a 10 to 20 minute hot soak, perform the Repair Procedure.

Parts required:
56028371AA Ignition Wire Shield

Repair procedure:
1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves about 25-30 mm (1 in.) in length. See diagram.
2. Install one sleeve around injector #3, with the slit on the upward facing side of the injector. Install the other sleeve with the slit on the downward facing side of the injector.
3. Confirm sleeve is flush to intake manifold surface around injector.
4. Check injector #3 wire and ensure that the injector is rotated to a 2 o'clock position.

 

Wow, some good info. Thank you. I had heard about the defect in the cylinder heads for these years... of coarse it was after I already had purchased it.

I am not sure how I feel about a hood vent, but I will look into that. I am more wondering about water going through it when it sits.

Is there any options for an aftermarket aluminum radiator and electric fan instead of a belt fan? This would be a better option to me as the fan could be wired to run all the time since I am in FL. I run a 3-core radiator with dual slim fans in my car, and it is the ****.

 

do the electric fan mod, there is also a way to set it on a timer after you turn the xj off...I wrapped my injectors with heat shield and it helped a little...also try buying pure gasoline, that's gas without ethanol..do a web search for gas stations near you that have it.....I just got a price on a new cowl hood. $580 installed and painted--seems super cheap. I might go that route instead of cutting the vents in. But the vents are the cheapest way to let the heat out

 

I saw a write up about using a headlight relay so the fan runs for a bit after you turn it off... not a bad idea. I will prob upgrade to a better radiator/fan setup in the future as FL is pretty brutal on the cooling.

I am going to mod this hood if anything, since my plan is to plasti-dip the whole jeep anyway, maybe I can cowl it myself then just prime it. I'm not real familiar with the hood vents so it seems if they let air out, they will let water in?

I think an upgraded radiator, fans with manual switch (1 that runs 24/7 and 1 that runs on a switch) with a cowl/vented hood should clear up the heat soak and any future cooling needs.

There is a station about 30min north of me that has 90 non ethanol... but that's a drive for normal fill ups.

 

yes the hood vents let water in. you have to fabricate a drip pan and channel water away from everything. It's super cheap compared to the cowl hood, unless you can use your current hood and make an aftermarket cowl work.

 

Hate to bring this back up... but I have looked over this Cruise Control and I'm coming up with nothin.

Looked over all the vacuum lines to the CC unit and the vacuum reservoir, all ok. Adjusted the brake switch, brake lights work fine. Still the CC light will come on for a couple seconds, then turn off, or if I hit the "set" button it turns off. I'm thinking one of the 3:

1) Brake light switch ($20)... maybe it's bad for the CC and not the brake lights?
2) Clock spring ($200)... maybe the ribon part for the CC is bad, but not the horn or airbag?
3) Cruise Control Servo ($75)... I took off the connector, made sure it was clean. Also turned on cruise with it unplugged, would do the same thing.

Does anyone have any more insight or things to check? I really don't want to just start changing out parts... I would really appreciate it.

 

I wouldnt be surprised at the clock spring another poster kn a different thread mentioned that their cruise wasn't working some time later horn went out and airbag light came on. He replaced the clock spring waiting to hear back if that took care of the cruise problem

 

It had 204k miles, so as far as one of those wearing out, it could be any one. The service manual lists a cruise servo vacuum test but doesn't say exactly HOW to do the test. Anyway to test any of these 3?