Related... but not the same

[lovemachine]

That's where the programmer comes in. The MOPAR engineers, bless their hearts, opened up the computer on the JK/U's, so you can go in and do a bunch of changes. Some good, some bad. It's actually nice in a way because with a higher end programmer you can adjust shift points, set the speedo for tire size, adjust shift points, turn the various nanny controls on or off, tune the engine for torque and horsepower...you can even tune for what type of gas you are going to burn. There's a lot there to work with. It's not like a TJ though, if one of those systems develops a glitch, you have an expensive, time consuming issue on your hands.

The traction control and stability system will absolutely heat your brakes up if you get into it for awhile off road. It's doing Jerry's trick of applying the brakes to control wheel spin, with the addition of trying to keep the direction that the front wheels are pointed correlated with the direction the JK is headed. I guess you can make it spaz out going side hill as well, though I haven't gotten there yet.

That shit is too confusing.

 

[glwood]

That shit is too confusing.

That's the world of JKs, especially the newest ones, and every other modern 4x4 out there. The TJ is the last of the computer-controlled traction device-free Jeeps.

Also, the 2007 JK was the only year that did not have TPMS.

 

[StG58]

That shit is too confusing.

Right?

At some point good TJ's are going to get as rare as good CJ's. It's kind of getting there now. Look at how far some people are willing to travel to snatch up the perfect TJ, and how much they are willing to pay. That's when knowing something about JK's is going to be important. I've got my perfect TJ, as do a bunch of other folks. I've also got a JKU. I need to know how to make that beast run off road in my conditions as best that it can. And how to keep it running without breaking the bank. The more I play with the JKU, the more I value my TJ, by the way.

That's the world of JKs, especially the newest ones, and every other modern 4x4 out there. The TJ is the last of the computer-controlled traction device-free Jeeps.

Also, the 2007 JK was the only year that did not have TPMS.

TPMS is just an expensive pain in the ass. Air down and it nags you. Yes, I know that my tire pressure is lower than you think I need, now go away.

And all those modern, computer controlled 4x4's have the same issues that the JK/U's do. At least the Jeep engineers gave us a way to "fix" the JK/U's so that we can actually drive them in the conditions we do. The changes from shifting into the different ranges in the transfer case are an example. The Jeep engineers at least tried to accommodate off road use. It seems that everyone else just set theirs up for use on road and maybe in the snow and called it good. Don't even get me started on the new Suburbans, for example.

 

[glwood]

Am I mistaken in the belief that the newer JLs will no longer have tuner access to the computer? Has anyone heard that rumor? I may be mixing up my vehicles again...

 

[StG58]

Am I mistaken in the belief that the newer JLs will no longer have tuner access to the computer? Has anyone heard that rumor? I may be mixing up my vehicles again...

I have no idea about anything on the JL's. Fiats with a Jeep badge and a trail rated sticker? We'll see when they get here, I guess. I just hope they aren't useless street queens.

 

[glwood]

I have no idea about anything on the JL's. Fiats with a Jeep badge and a trail rated sticker? We'll see when they get here, I guess. I just hope they aren't useless street queens.

Same here. I've seen nothing but 'spy shots', and none of those looked too promising. I can't see myself ever buying a JL. I would hope if I was ever in the market for a newer Jeep, the '13-16 JK would be the last I would consider.

 

[Chris]

I don't think there can be any argument that stock versus stock, a JK Rubicon (or JKU Rubicon) would out wheel a TJ Rubicon off-road, given that both drivers were equal in skill level.

They don't make new vehicles to be downgrades over previous ones. However, there's a bit that needs to be considered here. With all the newer and more modern technology that comes on the JKs, it also drastically increases the complexity of nearly everything.

That being the case, when something brakes, it's likely going to be twice as frustrating to fix, twice as expensive, and much more likely that you won't be able to do it yourself without special tools and / or computer systems.

This brings to light the real advantage of the TJ. It's mostly a very simply vehicle! Sure, it has electronics, but they are much older electronics that are controlling much fewer things than the electronics found on the JKs.

Some people don't mind having the new vehicle with all the gizmos. When it breaks, they just take it into the dealer and have them fix it, no big deal. I totally get that!

However, if you're like me, you like knowing that you can of 95% of it yourself when it breaks. Not just because you can, but because what happens if you're in a remote area and something breaks? It's a lot nicer knowing that you have a much better chance of fixing it yourself on an older vehicle like a TJ.

Still, both great vehicles, no argument there! Probably just different buyers in mind I think.

 

[Fouledplugs]

The TJ compared to the JKU "off road" is interesting. The TJ SE has nothing in the way of computer assistance on it, and the JKU has a ton of goodies that "help" you drive under various conditions. My SE doesn't even have anti-lock brakes. The JKU has anti-lock brakes, traction control, a stability system, hill decent and at least one more nanny control that escapes me at the moment. When you take the TJ out, you just drive it to the best of your abilities. It goes where you point it and does what you tell it. Not necessarily so on the JKU.

Lifting a JKU or even putting larger tires on it changes the inputs to the computer and also changes how it reacts. Most of the changes are subtle, and barely noticeable, but they are there. One example that comes to mind is when the wife was learning how to hill climb on a loose surface. The traction control was actually fighting her. With the traction control on in 2wd the JKU would bog down and try to dig the rear tires in. In 4hi, it was better but still noticeable. It did OK in 4lo. Most of these nanny systems can be turned off once you learn the routine, but shut the rig off and you have to do the dance all over again. Each selection in the transfer case has a different program for the nanny systems in the computer. That can be a little disconcerting at times as the JKU reacts differently than you were expecting depending on 2x, 4hi or 4lo. Even just going above the tire size that came stock on a particular JKU has a pronounced effect on performance. That's both on road and off road. My best advice is to budget in a good programmer if you decide that a JK/U is going to join the stable.

We're still playing with the JKU off road, and learning what it likes and doesn't like. More on this later if anyone is interested.

I love the fact that the JK/U PCM can be modded. Its a very unfortunate fact that the TJ/LJ PCM is pretty locked down.

 

[StG58]

I love the fact that the JK/U PCM can be modded. Its a very unfortunate fact that the TJ/LJ PCM is pretty locked down.

It is unfortunate, but the upside is the only thing that really goes bad in a TJ is the soldered connections. The EPROM inside, the brains if you will, is pretty stable. It's rarely the issue when the computer goes bad. If you have the hair, you could fix it yourself. Well, you may go through a couple of three before you get right...but I've heard and read of it being done. Actually have instructions for that someplace. After reading through those, and looking at all the pictures and such I decided to have mine rebuilt professionally. It was worth me not learning to solder on my own ECM. Someday, maybe.

It's no doubt that the JK/UR's are at least as capable as a TJR. But I've read discussions where the computers were fighting what the driver was trying to do. Maybe, maybe not. I do know that the computers will heat the brakes right up trying to keep our JKU out of trouble. Something as simple as bigger tires (35's are easy on a JK) and a set of Black Magic pads might just push it over the edge. At least with the much simpler TJ you know what you're biting off, and know or can find out what to do.

The JKU is a great rig, but the learning curve is pretty steep to figure out what needs to be done. Most of the mods tend to go towards angry eyes, lights, and really big tires. The folks that get them to work are pretty close mouthed about how they did it. Probably because they catch a lot of shit over it. The mall crawlers don't want to know and the TJ folks just bad mouth their rides, mostly. No fun in that, and no exchange of useful information.

I watched a JKR up in an off road park on the Olympic Peninsula last summer. I don't know what all he had done, but his front axle looked to be worth more than my SE, with mods. He was having no trouble whatsoever in a steep rock garden. He even stopped in the middle, did a 180, and went right back down. Didn't get to talk to him.