Eagle

A couple of points: (a) A 2.5L 4-cyl probably came from the factory with 195/75 or at most 205/75 tires, so running 235s is already way oversized for that vehicle. In fact, a 235/75 is virtually the same as a 30x9.50, just a tad narrower. (B) Adding a transfer case doesn't affect your gearing. The 2WD position is a 1:1 ratio. If you're happy with the gearing now, stay with it. But more than likely if you find a 2.5L XJ or MJ with 4WD it will be mated to a 5-speed. In that event, going to 4.10s will allow you to take advantage of the improved crawl ratio for off-road while maintaining driveability on pavement.

You may NOT be talking about closed loop, if you disconnected the TPS. The ECU requires input from several different sensors to properly control the air-fuel mix and the ignition timing. If you disconnect one of the required sensors, I suspect the ECU may just default to open loop mode -- which will run, but it's overly rich and your gas mileage will suck. Open loop is intended only for warm-up.

But it's not a fixed difference. What does a tachometer do? It counts revolutions. It does that by counting ignition pulses. For a 4-cylinder, 2 pulses = 1 revolution. But for a 6-cylinder, it needs 3 pulses for 1 revolution. So ... Take a 6-cylinder tachometer. In a 4.0L vehicle, 2100 RPM needs 2100 x 3 = 6300 ignition pulses. Now put that tach on a 4-cylinder. Run it up to where it reads 2100 RPM. That's still 6300 pulses, but in a 4-banger 6300 ignition pulses is 3150 RPM. It's not off by 100 RPM, it's off by 50 percent.

The 4.0L tach should already have a potentiometer. The clusters from 1988 and newer do have it. 1986 and older do not, but a 2.8 is a 6-cylinder, so it will be properly calibrated for a 4.0L. 1987 is the question mark year -- I don't know if they had a potentiometer or not, or if it showed up as a mid-year change.

So you're willing to tear into an axle of unknown condition are do all the work of installing your gears (which you will have to take out of this axle) into a new one -- but you don't want to just replace the axle seals in the one you have? Doesn't make any sense to me, but it's your truck, your time, and your money.

The Grand Cherokee ZJ also uses a Dana 30 in front, but that's a low pinion so it's actually weaker than yours. What you're looking for is just late model axle shafts, which have larger u-joints.

Yes.

I would expect a tank from a pick-n-pull to be full of leaks. Just buy a new MJ tank -- they aren't all that expensive. No, a Cherokee tank won't work. They are completely different.

Use the YJ hoses. Bending the original MJ hard lines is (IMHO) a HUGE risk. The metal is 20 years old in the newest possible MJ (a 1992). There's a high probability that if you try to bend it ... it'll crack. You're buying new hoses anyway, so just buy longer ones. The YJ hoses will work fine at stock height and are long enough for about a 4" lift.

Any 4-cylinder cluster from 1984 through 1990 will work. You can also get a cluster from a 6-cylinder, 1988 through 1990 -- those have a potentiometer on the back of the tachometer to allow you to calibrate it for the 4-cylinder engine.

Dead how? No spark? No compression? No ___?

An '89 is a Renix computer, and those cannot be reflashed. High idle is usually caused by the idle air controller on the throttle body.

That presupposes two things that don't work on the 2000 4.0L: (1) You need to remove a spark plug to feel if #1 is coming up on compression or exhaust; and (2) You have to be able to see the timing marks on the front of the engine. I'm old enough to have grown up with points and condensers and actually setting the timing every time we did a "tune-up." Which, back then, we did every 10,000 miles. I know what the timing marks look like -- and they aren't visible on the 2000 XJ. And I don't feel like fighting the idiot coil rail a second time just to pull ONE spark plug so I can feel for compression while I crank. I was hoping you would tell me that Jeep thought about this and made provision for it. I guess not.

Somebody sold you some bad dope. Are YOU not aware that when the Liberty was in final testing, Jeep did as they had always done and drove one over the Rubicon Trail? And that it was so BAD that to get it through they had to manually pile stones at many of the obstacles to make approach ramps, and they still had to push or pull it over some obstacles? Yeah, it's just a wonderful off-road vehicle. Not. You can't go by articles from other countries -- they don't generally have a clue as to what 4-wheeling is about. Heck, in my wife's native country they call anything with 4WD a "Jeep." On the trip when I first met her, I went in order to go wheeling with an off-road club there, one of whose members had invited me. So we're out in the middle of an ocean of sand dunes, standing next to his 2000 Cherokee Classic, and we hear an engine over one of the dunes. "Here comes Ivan and my old Jeep," says my host. Cool, I think, I get to see what he used to drive. And what he used to drive turned out to be a Daihatsu Rocky. To them it was a 'Jeep" -- hey, it has four-wheel drive ...

Looks interesting. Any easy way to line up #1 at TDC/compression without having to remove the coil rail and the #1 spark plug?

I found the TSB on-line. My problem is #6, not #3. I get rough starts with COLD starts -- like after being parked overnight. And it doesn't go away a few seconds or a minute after a rough start. Also, this XJ doesn't have the retro-fit leaf guard on the manifold, so there's less heat to trap. And it isn't that hot here -- today was the hottest day since early April, and it only got up to about 72 degrees. This is a 12-year old vehicle that has gone 96,000 miles, and this problem just showed up within the past ten days or so. I'll think about wrapping some insulation on the injectors, but it doesn't sound like a slam dunk from here.

I sort of think that wrapping some tape around a clutch alignment tool that's "close" is probably not going to get the job done. We used to have a saying in the Army: "Close only counts with horseshoes and hand grenades." Well even testing the clutch disc on the input shaft on the bench that disc was really tight. Okay. But SOMETHING is interfering. I've bench pressed enough transmissions onto engines lying under the car on a gravel driveway to have learned that it doesn't take much misalignment to prevent the transmission from bolting up.

What? 2000 XJ. Coil-on-rail. There are three coils, and each fires two cylinders. If one of them was bad, I should have lost both #5 and #6.

I sort of think that wrapping some tape around a clutch alignment tool that's "close" is probably not going to get the job done. We used to have a saying in the Army: "Close only counts with horseshoes and hand grenades."

That was my first thought, but I figured it wouldn't hurt to ask the resident Jeep techs here if the factory has any diagnostic tree to follow for such symptoms. The XJ has 96,000 miles on it, BTW.

This is in the Pub because it's about my wife's 2000 XJ, so there's no cross-over to the Comanche. I'm stumped and I need diagnostic suggestions. My wife is away and I've been driving her XJ because my newer one is overdue for an oil change and my old one needs a front hub. About ten days ago, I stopped at the post office. When I came out and fired up the engine, it sputtered a couple of times, ran VERY rough for a few seconds ... then stalled. When I restarted it, the check engine light was on. It idled much slower than normal for a few seconds, then stalled again. Restarted a second time, NO check engine light, still ran rough, but it kept running. I knew I was long overdue for spark plugs, so I grabbed a set and installed them. It seemed to run smoothly/normally -- for a day or so. Then I began to notice that, when stopped at traffic lights in Drive, every few seconds the engine would give a little skip/burp/stumble. Twice it died, but restarted immediately. Then it seemed to smooth out. Until today. Today it got MUCH worse, and late this afternoon it lit up the check engine light and threw a code. P0306 -- Cylinder #6 misfire. Okay: The code tells me #6 is misfiring, and that's how it felt -- like I was only running on 4 or 5 out of the 6 cylinders. But the code doesn't give me any hint WHY it's misfiring. This is a 2000, so it has coil-on-rail ignition. I can't just pull a plug wire and check for spark. I have a bottle of injector cleaner in the tank, and that has been working for several days. What else can I do to try to zero in on what the cause of this is? I need to get this fixed before my wife gets home. (Fortunately, I have a couple/few weeks, but I would rather get it now rather than wait for the mast minute. Any suggestions? Should I swap a couple of injectors to see if the misfire moves to another cylinder? I know they are rated for less flow, but could I pull an injector from a Renix engine (of which I have multiple) and try that? I never drive hard in the XJs, so the injector would never need to put out full capacity, and I would use it only for diagnosis. If that shows the injector to be the problem, I'd buy the correct replacement. Got any other suggestions?

Scared? You say that as though Chrysler had somehow been hurt by the Comanche. The truth was, they pulled the plug on the Comanche because they could see the Jeep people would rather buy the Comanche, and Chrysler wanted us to buy the Dakota. They weren't about to pull the plug on the Dakota, so the Comanche had to go. And they won't build a new Jeep truck now for the same reason -- they don't want to compete against their own Ram trucks. There's really no reason to build an all-new full-size Jeep truck. Once you get into the 2500 and 3500 series, the Rams use the same solid axle, 4-link front suspension as the XJ and MJ. What Jeep does need is a small, Jeep-size pickup.

Being an olde pharte, I don't like Tupperware guns. I prefer traditional, all steel firearms.

If you remove that top "cap" inside the cab, that won't get you access into the frame rails. The sheet metal floor runs across the top of the rail, then the "cap" is welded on over the floor pan. Where are you seeing rust inside the frame rail? Are you sure it's not just rust from the cap? I don't think you CAN see inside the frame rail.

I would never install a used track bar. It's just not worth it.