Eagle

FWIW, the Renix 4.0L engine generally produces better gas mileage than the HO. I own an '87 MJ 4.0L, an '88 XJ 4.0L and an '88 MJ 4.0L, a 2000 XJ 4.0L 5-speed and a 2000 XJ 4.0L auto. The '88s get better mileage. The 2000 XJ auto gets around 16 MPG in mixed driving. The '88 MJ was getting around 18 to 19 when I used it regularly, the '88 XJ gets 18 to 20 MPG and has delivered a best-ever of 28 MPG on a weekend trip from Connecticut to Vermont, loaded down with a lady friend, two kids, and gear for a long weekend. Unless your injectors are massively oversized, it shouldn't be running rich. The O2 sensor controls the duty cycle of the injectors to keep the mixture in the optimum range. When did you last replace the O2 sensor? When it fails, the ECU goes into open loop mode and defaults to a rich mixture because it thinks the engine is still warming up. This could also happen if the ECU temp sensor (the one on the side of the block, not the one at the rear of the head) is bad.

Yeah, I know. I have no idea how much longer Old Faithful can last, but I doubt it'll be more than another year or two. I would like to make 300,000 miles (it's now at 287,000). I really didn't want to sink any more money into it, but I remember that the Renix-era injectors are known for separating between the metal and plastic body, so I girded my loins and ordered a set off Amazon. Which means I can't get it running this weekend.

My '88 XJ has been off the road since my wife died four years ago. Now that the snow has receded, I was able to get underneath and patch the fuel leak -- I thought it was a gas line, turned out to be the metal fuel filter had rusted through. Got that all fixed, tried to start it this morning -- and all six injectors are leaking. What's a good source for injector O-rings?

My '88 4.0L MJ is almost that bad (not quite). I'm still considering options. I don't plan to use mine for off-road any more, and I don't plan on tires larger than 235/75R15s or possibly 30s, so I'm seriously considering grafting on the rear quarters from a 2-door XJ. The wheel arches will be a little smaller than proper MJ arches, but I think it will be easier to hide the carnage that way.

Are you talking about a 5-speed with a floor shift, or an automatic with a column shift? For 5-speeds, the only MJ I've ever seen with a straight(-ish) shifter is my '88, and it's because it has a tranny and shifter out of a Wrangler.

There was -- used on all 1987-1/2 thru 1990 XJs and MJs that didn't have cruise.

Great idea. I was thinking about Nylocks -- castle nuts never occurred to me.

It worked. When Chrysler took over, they immediately started looking for ways to save pennies, so they eliminated anything they thought they could get away with[out].

Doesn't someone offer a reinforcement plate for the "frame rail" where the track bar bracket mounts? I would look for that, and use Loctite on the bolts.

If the lights work (correctly), they have a ground. Keep in mind that if there is a bad ground, one circuit/filament may seek a ground by back-feeding through the other filament. That's when you start seeing funky behavior from the lights.

It shouldn't lean it out. The oxygen sensor is what controls the mixture in closed loop mode. If that sees a lean condition, it tells the injectors to feed more gas. Several years ago, on a trail ride, one of the guys either broke his exhaust manifold, or lost a couple of manifold bolts. That cause an air leak that fooled the O2 sensor into thinking he was running lean, so it enrichened the mixture to the point that there as raw gas coming out of the cylinders and burning in the manifold. He limped off the trail and, by the time we got to the trailhead, it was getting dark and his exhaust manifold was glowing bright red.

Front or rear? Going straight, or turning? In front of wheel or behind?

If it has passed before, it should pass again. Drum brakes do work, but they require periodic adjustment because the self adjusters don't work all that well, and most people don't know how to make them adjust anyway. Step one: Remove the rear drums and see if there's any lining material left on the shoes. If so -- replace the drums, adjust the brakes, and retest.

Before you do anything -- where is it rubbing, and how much?

If that's an '87, what's with the coolant recovery bottle by the firewall at the top of the photo? Does your vehicle have a replacement radiator with a radiator cap?

Yes, you can. The standard turn signal blinker is load-sensitive. It's set to blink at the normal rate when all the turn signal bulbs are working. If one bulb burns out, the load changes and the module causes the signals to blink faster. That's intended to let you know a bulb is burned out ... but most people don't know that. The problem is that adding a trailer, with additional lights, also changes the load and affects the blink rate. So for trailer towing they use a heavy-duty, non-load-sensitive blinker module. It always flashes at the same rate, regardless of the load. That might be all you need to solve your issue.

It's not polite to gloat!

Finding a good, rust-free Comanche anywhere is going to be a pain. The newest MJs are now 26 years old.

For anyone else with a high idle problem on a Renix, there's another possible cause. The throttle cable from the gas peddle doesn't go direct to the throttle body, it goes to a mechanical bellcrank assebly that has a pivot located down on the driver's side frame rail, below the master cylinder. From there the bellcrank has a rod that extends up to move the throttle plate. That pivot mechanism can get dirty and rusty. I've found that period lubrication with PB Blaster cures my fast idle problems when they show up.

Every week, on Wednesday -- regular as a train schedule. Two weeks ago I lost power on Wednesday and it was out for two days. Last week the power went out on Wednesday but they got it fixed in one day. Got my fingers crossed on this one -- forcast was for up to 18 inches of heavy, wet snow, and that's what brings down trees ... and power lines.

So you're talking about your modified Charokee, not "the" Cherokee.

The Cherokee weighs 1000 pounds more than what? Curb weight for the 89 MJ ranged from a low of 2897 pounds for a 2WD shortbed to a high of 3130 for a 4WD longbed. (Source 1989 MJ Owners manual) Curb weight for an XJ was 3357 pounds (source Wikipedia -- weight not given in '94 FSM). I've seen other sources that said the Comanche curb weight was higher than the Cherokee.

3.07 gears are not suited to towing.

Make certain the guy at Autozone bench tests the new alternator before you leave the store with it. Autozone's Delco alternators seem to have about a 75% dead-on-arrival ratio -- and that applies even to their "top of the line," purportedly new units.

Front bumper is tweaked. Grille is falling out. Tailgate is bent. Wheel arches inside the bed are bashed up. That thing looks to me like a beater truck that just had a Earl Schieb paint job thrown on it.