gogmorgo

I'll have to apologize for my late night ranting, as that did come off a little more harsh than it needed to. In a lot of ways, you guys are right. I don't see it so much here, possibly because there are more engineering students who grew up on farms, maintaining equipment, etc, than when I was at school in Ontario, where it seemed a lot of the engineering students were there simply because their parents wanted them to have a decent job and honestly couldn't design worth $#!&. And those are the people who rise through the ranks and end up making the $#!&ty decisions, believing they are better than everyone else, and everything that comes out of their mouth is gold, and they can never be wrong. I've mentioned it a few times that I'm on my school's FSAE team. Every year we design a small racecar, we build it ourselves out of mostly custom built parts, and we maintain them ourselves. Every year, we start pretty much from scratch, although lots of parts get based pretty heavily off parts from the previous year's car, and we do all the assembly ourselves. Because this is a competition, we try to improve the car every year. The last few years, there was a really big push towards easier maintenance, which was mostly a success. One guy can pull the entire powertrain out of last year's car, all the way from the engine to the wheel hubs, in under a half hour. But the car is so long and wide that it has trouble making it around the tighter corners in the autocross course at competition. So this year, we pulled six inches out of the wheelbase. Can of worms doesn't even begin to describe what that involves. As one example, the diff's gear ratio is much taller than we'd like, but was chosen because "that's the biggest we can fit into that spot and it can't go anywhere else". And if that spot in the chassis gets bigger, we'd lose any semblance of chassis rigidity, or the suspension geometry would go to $#!&. 50% of design is unfortunately compromising. I really do think that all engineering students should have to participate in something like this. And that's why the people who do are more likely to get hired, because they actually have experience doing the things the got hired for. Sadly, out of the 2000 students in the college of engineering here, likely only about 50 of them feel they have enough time to dedicate to this kind of extra-curricular project.

No! Education is not at issue here. Nor are the engineers. What is at issue is that engines are put into vehicles as whole units, complete with all accessories. This is because automobile manufacturers are businesses, and it's a pointless waste of resources to completely design every component of every car to be model-specific. You guys like it when you can find components on other vehicles that fit your MJ. Imagine if no cars had interchangeable parts. With lots of parts on an MJ, you get that. It's no fun trying to replace something that didn't get used on any other vehicle, is it? So you have an engineer who has to put this engine, the size, shape, and configuration of components of which he can't change, and he has to put it into an engine compartment he can't really change due to more important design priorities (like safety regulations, vehicle performance requirements, and exterior aesthetics, because you can't sell an ugly car), and he doesn't have much choice as to what goes where. Mostly his job is to make sure that the engine can do its job, doesn't interfere with other components' jobs, and especially doesn't fall out of the car, because that's really all he can do, since an artist drew the car, and the boss man says it has to look like that. Have you ever designed a car? Do you know what all is involved, where you have to compromise? Cars don't break down very often, and repairs are rarely time-sensitive, so it's a pretty low priority. One of the highest priorities is unfortunately cost reduction. You want a car that's as easy to repair quickly as a Formula 1 car, you'll have to pay for an F1 car. Seriously, don't knock someone's education unless you've been through it and actually know what you're talking about. I hear so many skilled mechanics and other skilled tradespeople saying things that are absolutely ridiculous and are completely against physics, like "engines need exhaust backpressure" or "if you get arc eye, mash up raw potato and put it on your eyes to suck the UV's back out of your them". What's missing from their education? Should they have spent a few years studying and working with fluid dynamics and light before becoming mechanics or welders?

Oh, yes, right. I forgot that with a fixed position housing you're turning the rotor, not the housing. Rotating the housing ccw would advance it, but I can't do that... First time I've ever done anything with a distributor I can't rotate.

I'm running 8 on mine... That really scares people, because most people have only seen it on a surface or a phone. I use it for the same reasons you do. You really can't CAD on OSX. Lots of people I know say they hate Apple because iTunes or Safari or <insert Apple program here> sucks. I can't entirely disagree with them, because despite how nicely polished and smooth-functioning and mostly bug free Apple's software is, I find that it can be incredibly finicky. If what you're doing with it isn't exactly the way Apple likes things, then you start to have issues. And if you grew up only ever using Windows, then the way Apple likes things won't necessarily make sense to you. It doesn't always make sense to me, and I grew up on a diet of Macintosh. Then again, there are things in Windows that don't make sense to me. Like maximising.

So I finally got out to look at the truck again today. I took it down to get me some breakfast, and on the way back it tried to die on me again once (but only once, as opposed to at every stop sign). So when I got back I checked the wires and everything, and it looked like it all checked out. I did notice the cap was a little loose ( could move the top of it a 1/4 inch), so I pulled it off, made sure it was seated properly and cranked it down. It seemed to be running better after that. Revving it from under the hood wasn't producing backfires, but I didn't actually drive it after putting the cap on better. I'll have to keep an eye on it, though. Despite the apparent brass, the cap that came with the new dizzy looks really cheap, so I may end up just putting my old cap back on. I also disconnected the battery, cleaned up the terminals while I had them off (they were somewhat corroded and coated in something that looked like peanut butter?) before putting them back on, and checked the codes again. Without starting it, I got 12 and 55, which I guess is what you'd expect right after disconnecting the battery... When I put initially put the distributor in last week, I chose a spot that was slightly counter clockwise of where my marks were, but the engine didn't fire up after a few cranks, so I moved the dizzy clockwise a tooth. That's when I noticed the whole housing seemed to be turned a bit clockwise from where the original was, so I figured I had to have it it in the right place. She fired on the first try, but didn't start, but it started and ran on the second crank. My buddy who was "helping" me (doing other unrelated things in the shop) points out that I didn't try very hard to start it before I moved the distributor, so I guess if once I get driving it and it's still running a little rougher, I'll have to go back a tooth. Assuming that backfiring out the exhaust means the timing is retarded and I would have to turn the distributor counter-clockwise to fix that, right?

What does a guy have to do to piss you off that badly? As someone who's never yet encountered a craigslist idiot, I have trouble understanding sometimes...

Might also want to seal off your air intake somehow. My dad once parked under a spruce tree for a couple hours, then spent a while trying to figure out it wasn't running very nicely. He took it to a 10-minute lube place because the oil needed changed anyway, and they found three pounds of green spruce cones in his air box. Damn squirrels!

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Being a unibody doesn't mean much in terms of wiring. Try disconnecting the trailer wiring. If it solves the issue, then you've likely got a short in it somewhere. Also, it seems to be pretty common for a diy trailer harness to be patched right into the taillights, and usually pretty badly at that, which can cause all kinds of issues when something fails. Another thing to check is to make sure you've got all the right bulbs. A single-filament bulb in a double-filament socket can wreak havoc.

Yeah, there's all kinds of things you should do but I'd honestly just do as Jim... Almost ten years ago, my Dad parked his '85 Chevy Van as it was in the back yard, and it sat there almost a year. A day before a family vacation, he went out, inflated the tires that were so low the rims had cut into the ground, jump started it from our car, and drove it over to insurance place to renew the plates, hitched up the camper, and we set out to the west coast through North Dakota the next day and had no issues whatsoever. Scary thing is I just realised he's more than likely still running those tires. :eek: He's been DDing that van for the last couple months, as my sister wrote off his car a few months back. That said, fuel stabilizer of some kind is more than a good idea. You don't want stale gas gumming up your engine. Your best option is to have someone you trust take if for a short drive a couple times a month.

Yeah, makes sense. Will do. Also, is a little bit of backfire when coming off throttle normal during the relearn? I couldn't get everything to line up exactly the same way with the new dizzy, so that's why I'm concerned. I don't think the rotor's more than 2 or 3 degrees from where it was, though, and it looks like the housing rotated by about the same. With going from the hold down clamp to the fork off the housing that the bolt slots into, there was only one way to put the new one in.

Oh, no, I didn't disconnect the battery. Should I do that?

Well, the new dizzy's in, and it seems to have solved the problem. I'm not quite sure I like the way she's running, but it's nothing too bad. Hopefully it clears up when she gets the map sorted back out. At any rate, there's no more stumbling, and power seems to have gone up quite a bit. Turns out new distributors come with a gasket, too, which looks a lot better than the fel-pro I got. I was also surprised that the cap and rotor have brass contacts and not aluminum, considering I only spent $42 on the distributor. Or at least they look like brass. They could easily just be plated... World Power Systems DST 4696.

Looks like city worker orange. Not a bad looking truck, not much rust. I'm jealous of that.

Hope you sister heals up. When I was living in the GTA, the busses freaked me out. I nearly got hit a few times, and someone got killed right in front of my school. The drivers were pretty much rally drivers... they had at least one pedal on the floorboard at all times. I once rode a bus at twice the limit through a school zone, completely ignoring crossing guards. Damn sure I reported that. Here in Saskatoon they're much better, but some drivers still have that issue.

http://saskatoon.kijiji.ca/c-cars-vehicles-cars-trucks-Last-call-for-jeep-parts-W0QQAdIdZ472807139 Winkler's about 120 miles from Grand Forks ND. Guy's parting it out and will scrap it in a couple weeks. After inquiring, most of the body and bed are rough, bumper isn't worth much, receiver hitch also in rough shape. Looks like it's gotten a few hard jerks during a recovery. Has a Dana 35. Looks like most of the front end and interior are going to an XJ :( But it does have a roll hoop for a long bed. Don't know what shape it's in though. I only caught a bit of the corner in a pic he sent me, but the whole truck seems to have been beat pretty hard. Edit: The owner just sent me this pic: Don't know how recent it is, because the other pics he sent me all have grass and mud and no snow. He also said the tail lights are busted. Figured I may as well post the other pics he sent.

... had that game for years and loved it. Didn't realize it was an MJ. Haven't played it for a long time, though.

... Gonna have to get me one of those deuce and a halfs one day... :drool: That's a pretty nice J20, too. Don't know if it's 10k nice, though. The only J10 or J20's I've seen have been in pretty poor shape. That one's a Beaut.

Yeah, probably. It got new pads and rotors last month, which was a huge improvement in dry pavement braking, but made the locking up worse. The rear shoes were replaced so it could pass a safety 7500 miles and a year and a half ago (at least according to the inspection doc I got from the PO), and the pedal's solid enough I don't think they need bled. Probably not having the load-sensing valve connected to the axle but still in the system, with the bar just dangling isn't helping anything. I've been meaning to wire it up to see if it makes a difference but haven't got around to it yet. I may simply have no rear brakes because of that, and it always has kinda felt that way... Reason I haven't done it yet is because I don't have anywhere warm and more importantly dry to crawl under it.

Did you even read the whole post? A long tube allows the exhaust gases to accelerate, which helps to pull the exhaust out of the engine. Power is of course highest at the point where the exhaust is flowing as fast as possible, but before the exhaust starts building pressure when the engine pumps it out faster than the exhaust can flow in the pipe. A modern catalytic converter doesn't provide much obstruction to exhaust, and you were mostly noticing the effects of the longer straight section of tube. Having the tail pipe go as far back as possible really helps that. As you noticed. When you push air into a wide open space, it slows down, but when you push it down a tube, it accelerates. But if your tube is too big for the amount of air you push through it, you don't move all of the air inside the tube, and the air that doesn't move interacts with the moving air, slowing it down. As the motor revs higher, it moves more air through it, so you would need an increasingly larger exhaust to be always at the point where you aren't compressing the fluid but have it moving as fast as possible. That's not really possible, so you pick the rpm where you want the most power boost and choose an appropriate exhaust diameter for that rpm. Stock exhaust on a 4.0 is set up for around peak torque, so changing it will mean you lose power at peak and generally in the low end, although if for whatever reason you want more power at higher rpm, you can choose a larger pipe, sacrificing low-end performance, which would work out pretty well for a turbocharged motor, since you want to keep the revs up anyway. JeepcoMJ... Venturi effect? Try again yourself. It never comes into play, nor did I bring it up. Since your exhaust gases are losing heat as they travel further from the engine, they lose pressure (Guy-Lussac's law). To conserve kinetic energy, the lower-pressure exhaust must then travel faster. So it's similar in result to the Venturi effect, but without needing to waste power from the engine to force the exhaust through a constriction. This also helps explain why Zack noticed a big difference after putting on the cat, since the reactions happening inside it take away a huge amount of heat, significantly reducing the pressure and thereby increasing the speed of the exhaust. To OP, sorry for the thread hijack... my bad.

If you just post the link directly into your reply, no fancy code or anything, it will be embedded in your post. Like this: http://www.youtube.com/watch?feature=player_detailpage&v=l38blGqVeHc

I'm a little mixed about the ABS thing. Growing up knowing about it, it's a whole different technique. I've never spent much time driving a vehicle with ABS (none of my parents' vehicles had it) but we had to learn to use it in driver's ed. It's very counter-intuitive, slamming the brakes full on to stop in low traction. Sometimes I wish my MJ had ABS, because the brakes really seem to enjoy locking up whenever there's a bit of ice on the road, much more so than anything else I've driven, despite the fact that they're not exactly all-stars on dry pavement...

"Back pressure" is a myth. You really don't want pressure building up in your exhaust. It will never help. That being said, fluid dynamics get kind of interesting. Your exhaust system has an optimum flow rate. If you aren't pumping enough exhaust you develop vortexes which slow down your flow. If you're pumping too much exhaust down it, you start building pressure, which also slows down the exhaust. Wider diameter pipes typically have higher optimum flow rates, and narrower pipes have lower optimum rates. If you get your exhaust moving fast enough, it will help to suck air out of your cylinders, meaning the engine doesn't need to work as hard to pump it out, so you get a bit of a power bump. You can take advantage of the power bump by choosing an exhaust system optimized to a specific rpm range, typically around peak torque. The higher the optimized rate, the higher up the rev range your bump, and you can gain low-end with a lower optimized flow rate. If you really want to get fancy, you can use butterfly valves and the like to alter the optimum flow rate of the exhaust to get power bumps at several rpm ranges. You can also use wave harmonics to "wave tune" your exhaust, effectively lining up the individual exhaust pulses from each cylinder to push the exhaust faster at specific rpm. So while the principle of "back pressure" is mostly sound, i.e. freer flowing setups lead to more high rpm power and more "constrictive" systems lead to better low end, the fact remains that if you ever start building pressure of any kind in your exhaust, you're just pointlessly wasting engine power to compress your exhaust. Also, the "constrictive" setup isn't actually constrictive until you're going faster than the optimum rpm, and even a more free flowing system can be constrictive if you're not going as fast as the optimum. As far as mpg's go, though, the best I've ever had was nearly 20mpg at ~1850rpm. I've never really got close to that number since. And I'm pretty sure it wasn't just a tailwind, because it was up and back down the same 100 mile section of highway. That said, 300,000 mile MJ is't going to do quite as well as some of those that have lived gentler lives. Honestly, the best way to improve your mpg is to avoid accelerating and idling (sitting at red lights etc) as much as possible.

Could be u-joints, either in the driveshaft or axles.

Don't know how much water you use, but you may find the electric tank won't heat up anywhere near as quickly as the gas one did. I have two sisters. When my parents changed out our gas tank to an electric when I was fourteen, I learned to be the first into the shower...