Eagle

I think you need to re-read what Eagle said. The 231 has 2HI - 4HI - N - 4LO The 242 has 2HI - 4HI Full Time - 4HI Part Time - N - 4LO ^^^ What he said. The 242 has ALL the same positions as the 231, PLUS the ADDITIONAL option of a full-time 4WD that can be driven on dry pavement. It is NOT always in AWD.

The 231 is very slightly stronger, which might be a concern if you plan to wheel hard with very large tires. Nonetheless, some of the guys in my chapter of NAXJA wheeled Chrokees with the 242 and never broke one. The 242 has all the same settings as the 231, PLUS the additional option of running in full-time 4WD on pavement. Having driven long-ish trips in blowing snow with a 231, I can tell you that constantly shifting into and out of 4WD as the road surface conditions change gets old in a hurry. The 242 is definitely the way to go.

Oh, I've been wrong more than I enjoy acknowledging. But I bought my '88 XJ new, and between that and a series of MJs I have logged nearly a half million miles behind Renix 4.0L engines. I have encountered the RPM spike upon startup multiple times, and it's my clue to dump a couple of cans of fuel system cleaner into the gas tank. The better fix is probably to remove the idle air controller and clean it, but it has to be adjusted when replacing so don't dive into that if you don't have the adjustment procedure documented.

Yeah, they have bumpers, but not factory replacements. They have the Fey universal step bumpers. Better than nothing ... but not much better. They're pretty ugly.

Don't have a clue regarding the heat. It does sound like it isn't getting warm enough to get into closed loop mode, but who knows why? Could be as simple as a stuck thermostat. As to the oil pressure, what's "high" to you? And what weight of oil are you running?

Any junk yard.

I don't know what "throaty" means to you ... to me a "throaty" exhaust would be something deep, mellow and powerful, like a Ford Mustang V8. But ... for your symptoms, it sounds like a clogged catalytic converter.

When starting a Renix, the RPMs should NOT spike to 1500 or 2000 RPM, and certainly not for 2 to 5 seconds. That's a sign of impending problems. It shouldn't go any higher than about 1,000 RPM, and it should drop back to normal idle (+/-650 RPM) virtually instantly.

Yes, but yours should be round (the "softball") rather than elongated (the "blimp"). You need it for your heater controls. The one for vehicles equipped with cruise control has two chambers, which is why it's elongated.

Since the part has been identified but not explained, allow me to elaborate. The heater controls are vacuum actuated. If (or "when" may be more accurate) you get a vacuum leak, you'll find that when going up hills or accelerating under load (when engine vacuum drops), you'll think you don't have heat. What happens is that the default position for the flappers is to send air to the defrost vents on the top of the dashboard. The "blimp" or "softball" stores some vacuum to hold the system during periods of heavy load on the engine, when the vacuum being produced isn't adequate to keep the controls open.

An MJ with a 4.0L and a 5-speed should have 3.07 gears. Did you change your gearing or axle(s)? Also, your tires are 16" and those were never offered on the MJ, and 245/70-16 is oversized for a late model XJ. My wife's 2000 XJ came from the factory with 225/70-16 tires ... they are the same size as 225/75-15. So they are oversized, and as you note the speedo should read slow. But if you have 3.55 gears and the speedo drive gear still thinks you have the original 3.07 gears, that would make the speedo read higher than actual speed. You need to pull the speedo drive gear, count the number of teeth, and compare it to the chart for your axle ratio and tire size.

Considering that the range starts at 100, what you're saying is that the needle barely moves at all. If it's anywhere between 100 and 210, you really have no idea what temperature it's telling you. The scale on the temp gauge is logarithmic, not linear.

There is no Cherokee V8.

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Could also be a thermostat that's stuck open so the engine never gets warmed up. Out of curiosity, how are you getting 110 degrees, since the scale on the temp gauge isn't linear and there's no mark for 110 degrees?

Yes, the large reservoir is for the front discs. If the small reservoir went empty, you have a leak. The most probably place is naturally the least accessible -- where the lines run along the frame above the fuel tank.

One of my NAXJA friends had this with an '89 XJ. He replaced just about everything in the system, with zero improvement. What finally fixed it was removing the factory proportioning valve and replacing it with an adjustable proportioning valve. However, I recognize that the MJ does not have a proportioning feature in the front metering block. So some diagnosis is in order. Back to basics: Have you removed the cover from the master cylinder to see if one or the other chamber is low -- or empty? That's the first step. The large chamber feeds the front brakes, the small chamber feeds the rear brakes. Check it out and let us know.

Over the years, I believe between the XJ, MJ and ZJ there are (were) at least four different diameter sway bars used. I would always go with the biggest, fattest sway bar I could get. Keep in mind, however, that with a stock vehicle (with any vehicle, actually) when you increase the roll stiffness in the front, you also increase understeer. That means you increase the tendency for the vehicle to plow off a corner nose-first if you hit the corner too fast. Conversely, if you add a sway bar to the rear or stiffen up the rear springs, you increase oversteer -- the tendency to let the tail spin out and go off a corner sideways or backwards. Personally, I prefer driving a vehicle with slight oversteer and I always try to set up my suspensions that way. Detroit (or Tokyo, I guess) builds cars for the average driver, and more drivers seem to be freaked by oversteer than by understeer, so just about any vehicle you can buy has the suspension tuned for slight understeer. Which is great if you sell replacement airbags.

They already can't. Drive down any street that has parallel parking and pay attention to the way cars are (allegedly) "parked." Seen the new Lincoln ads? Automatic parallel parking! Where's that :barf: icon when you need it?

I have no idea. First guess would be that the chain snapped, but that's only a guess. You'll just have to drop the transfer case and open it up for inspection, I'm afraid.

I've driven ABS once, in a rental car in Ann Arbor, Michigan, in winter. It was one of the more frightening experiences of my 60+ years of life. Think about it -- what does ABS do? It releases the brakes when you are trying to apply them. There is simply no way they can make a vehicle stop any faster than the driving conditions allow, but because people who buy them have been brainwashed into thinking that ABS magically makes the brakes work as well on ice as they do on dry pavement ... they drive accordingly. It's like 4WD -- on any given snow storm morning, it's rare in my half hour commute not to pass at least two SUVs in a ditch because they thought having 4WD (or AWD) meant they didn't need to slow down in slippery conditions. I want no part of them.

They don't return to zero when you shut off the engine. Let it sit for a couple/few hours, and when you turn the key ON they'll go to zero (or 100, in the case of the temperature gauge).

I have also thought about the fact that a carburetor makes a lot more sense for a serious trekking vehicle. With EFI (throttle body or multi-port), if you're way out in the boonies and you lose the fuel pump or injection, you're basically toast. In the past, I have hooked up a drip can under the hood to provide gravity feed for a carburetor and been able to drive the vehicle several miles to get back to home base. I'd like to try it just to say I did it ... what holds me back is that Connecticut has mandatory emissions inspections, and I don't think a retrofit of an EFI vehicle to carburetor would pass emissions.

All of the posts provided pretty specific information that was directly responsive to your question. If you don't understand what any of it means, with all due respect how can you possibly expect to do anything with the vehicle?

The 4.0L HO started with the 1991 model year. It has the ECU in the engine compartment, on the left front fender near the air box. The older Renix vehicles have the ECU in the cabin, above the driver's right foot.