jteckmann

Renix 4.0's used an MPI set-up, so these mods will work. I've got the same set-up as you: Renix 2.5's used TBI - just one injector located in the throttle body (here's what ours looks like: 86-90 2.5. The 2.5 didn't switch to MPI until '91. As far as I know, our options are limited. I believe Python still carries an injector for ours, but I don't know how much of an upgrade it is over stock/OEM. I've also heard of some people who have upgraded to a system from Clifford's Performance, but it involves headers, new intake manifold, a whole new TBI set-up, and costs upwards of $2-$3K. For that kind of money, you're probably just better off swapping to a +'91 2.5 or a 4.0. IMO, the best bang for the buck on a Renix 2.5 is to simply open up the exhaust and ditch the mechanical cooling fan for an electric one.

I've got the exact same set-up ('86, 2.5 TBI) and experienced the same symptoms. If the fuel pump & TPS check out fine, might try checking between your coil and Ignition Control Module. It's a 2-piece unit. Two torx-screws hold the coil in. I checked mine, and was amazed at the junk that had built up in there - the connections to the ICM were corroded pretty bad, and pretty loose around the coil. I cleaned things up as best I could, and that seemed to halt the problem long enough for me to get home. I'm 99% sure that was the root cause of the problem in my case. Mine was due for a tune-up anyways, so I just went ahead and ordered a new ICM, coil, cap & rotor, plugs & wires and changed everything at once, and the issue went away.

Back to the crankcase ventilator - I have an '86 2.5, and the one on mine looks absolutely nothing like that. I assume at one point a PO just picked a generic one off the shelf at AutoZone, so I've always been purchasing one just like it. Does it really matter? Isn't there a model that will work that's still available in stores, without having to track them down at JY's? I ask because I currently have a rough idle gremlin hunt I'm on - and I'd feel pretty stupid if it turns out I just had the wrong crankcase vent this whole time.

I have a '78 J20 - it's an absolute beast and I love it. I think they're great trucks. They definitely have their quirks, and the AMC V8's are notorious for oiling issues, but overall they're torquey, well-built engines. The 401 & 360 had good production #'s in the 70's, and remained basically unchanged for years, so there is still a good amount of after-market support and a very knowledgable community of FSJ people out there. Here's an original review of a '78 J20: http://home.off-road.com/~ozifsja/tech/reviews/j-20.htm Also, check out ifsja.org - answers to any and all of your qestions about Full-size Jeeps.

Here's a thread talking about a Cummins 4bt in an MJ (sounds like a lot of expense/trouble, but it can be done): Link From what I've read, Cummins 4bts and 3.3 were used in a lot of delivery trucks & bread wagons, and some shuttle buses. So while it'd require a lot of hunting, you can find 'em in junkyards. And here's a forum that has tons of info on Diesel swaps in general: Diesel Page Forums I have a full-size J20 with a very tired 401 in it. I'm currently gathering parts and searching for a suitable donor so I can go with the GM 6.2/6.5 diesel swap and turn it into a fry-burner. For the big truck, it makes tons of sense - the 6.2 and parts are readily available, everything is pretty much bolt-in, and people who have done the swap are reporting average mpg's in the mid-20's while still being able to work it like a full-sized truck should be. From what I've checked out, the 6.2/6.5 shares all the same mounts/dimensions, bellhousing with a SBC, and is about 200lbs heavier. I've seen people dropping SBC's into MJ's and XJ's - so I'd think 6.2 into a MJ would be possible as well - but IMO that's a lot of work/expense and extra weight in the front to deal with. So unless you're just truly a diesel fan, I don't think it'd be worth it. Depends on if you're looking purely for mpg or the ability to home-brew your own fuel. I have a 2.5L 4sp MJ that I use as my DD. I've found that as long as I keep the engine well-maintained and drive with a light foot, I'm already at 30mpg in mixed driving. At one point I considered a diesel swap for the MJ, but decided that after the expense of finding a suitable donor and the conversion work, any savings from increased mpg and the cost difference in diesel would be years down the road.

Awesome. I've heard about Griffon, and watching those video makes me wish I could ride it. I'm a total coaster junky, when I lived on the east coast, my wife's fam was in Tampa, so I had an excuse to go to that Busch Gardens all the time. I was living in Atlanta, but unfortunately that Six Flags was a complete dive while I was there (they had just built a Batman coaster and repainted an older one to be the Riddler, they had 2 cool wooden ones, but that was it). Then, as soon as I move away, that park suddenly goes on a building spree, and from what I here now has lots of cool coasters. One bummer about being up in the PacNW is no great coasters are nearby. There's a good wooden one in Idaho that's a 6 hour drive, and the rest are down in SoCal. I'm taking a trip to LA in a month, and will finally get to go to that Six Flags and have my coaster fix. I'm still trying to talk the wife into a weekend at Cedar Point in OH. That place is supposedly the coaster mecca.

The PO on my Comanche had cut out the factory brackets and left some gaping holes back there. I simply cut a piece of plywood to size to cover the old holes and used the template to cut new openings in the middle for my 6x9's (and used the grills that came with the speakers for protection). I then sanded it, painted it black, and covered the back with some Dynamat. I screwed the 4 corners directly onto the plastic and used some black silicone to make a gasket. Then I stuffed the area behind the plastic trim/between the sheet metal with some cheap polyfill for more sound-proofing. Worked great for me - no rattles and the sound is great.

Thanks for the info guys. I found that Accel makes a high performance coil (part #: 140011) and cap&rotor (8130) for the '86 2.5L When I get a free weekend, I'll put in the parts and then report back if it makes a noticeable difference. The only reason I'm even doing this is because I get the most expensive part for free. That 2.5L struggles on even the slightest hill, but I love the 30mpg out of a daily driver.

Thanks - that's kinda what I figured. I can get the ignition box for free, and generic MSD coil runs about $60, so it's probably worth a try. I've noticed that there are lots of parts available for later years of the 2.5L - but my understanding is those are the years after the Chryco takeover, and those aren't "Renix" . Are some parts out of those (i.e. just the cap & rotor) interchangeable?

I have and '86 MJ with a TBI 2.5L. I now have access to a friend's old MSD Blaster ignition, and was considering purchasing the coil/cap&rotor/wires to go along with it. Is this a worthwhile upgrade for the 2.5? I'm not expecting to perform miracles with this engine - it's my DD and I don't do heavy wheeling. But if the MSD would boost my mpg a little and add a tad more pep in mixed driving, I'd be happy. However, I was looking through the MSD application guides, and can't find any part #'s for an '86 2.5L. I understand this is a Renix engine, so is the upgrade even possible? Or is it just a matter of using generic GM or Motorcraft coils and cap&rotors? (sorry, when it comes to ignition specifics on these things, I'm definitely a noob) Firsthand accounts or the parts #'s of the components used from anyone who's tried this would be appreciated ....