jteckmann

Ah, OK. But if I found a 2-piece speedo cable at the junkyard, could I use that? I have a list of misc. parts I need to grab next time I make a JY trip ... so I may just poke around and see if I get lucky. Worth a try before I order the magnet kit, I guess. Thanks for the heads-up about the over-rev. I'll definitely be aware of it. Shouldn't be much of a problem, though. I don't use cruise control much at all, and never when I'm in traffic. ... but I've been doing a lot of trips out to Eastern WA lately and there are some long, flat stretches where I stay in 4th, and the cruise will come in handy to keep my leg drom going dead. :cheers:

No clutch pedal cutout to wire in. According to the manual, the cutout is built in and the unit senses the spikes in rpm when the clutch is depressed from the tach feed. The connections I need are : 12V accessory power, tach, brake cutout, vehicle speed, and vacuum. If the vehicle has an existing speed sensor, I wire into that - if not, then I install the magnet kit on the driveshaft. Then the settings on the unit are programed based on # of cylinders, whether the tach signal's coming from the coil or the ECM, etc ... I contacted Audiovox, and getting a replacement magnet kit is no big deal. I'm just hesitant because I foresee issues with damaging the sensor/magnets hanging under the truck, etc. That's why I was wondering about other options. I'm curious about what MJ/XJ's from that era used for their factory cruise set up - if it was even an option with a manual transmission. I know some vehicles used to have one attached to the gauge cluster or speedo cable. But I've tried part searches for a Jeep speed sensor, and I get zero results.

Hi all. I have an '86 MJ, 2.5, 4sp manual. Renix. I have an used aftermarket cruise control system (Audiovox CCS100) that I pulled off a car my parents were getting rid of. I was able to download instructions from the web, so I'm pretty clear on how to hook it up. Problem is, the vehicle it came from was an auto tranny and it had a speed sensor, so the magnet kit for it is missing. So what are my options to get it running in my Comanche? I don't think my truck doesn't has the necessary speed sensor for me to plug into - or does it? I assume cruise was an option on these things, so what did the factory set up use - is there a part I can grab from the junkyard? Or do I just need to call Audiovox and order the magnet kit that originally came with the thing? Thanks.

Hi all - I've got an '86 2.5L. I ordered a replacement valve cover for it (w/o gasket), and when it arrived in the mail, I see that it already has a thin rubber seal built in along the edge. As far as I can tell, my original one did not have that. Is this supposed to take the place of the separate gasket? Or should I install it along with the rubber gasket I picked up at AutoZone? I'm just worried with that much stuff crammed under there, it won't be a good seal, or I'm likely to over-tighten it. Also, is there a specific order for tightening the bolts? My old cover had a crack in the middle that I tried repairing with epoxy a few times. I'd install by tightening the end bolts first, then working my way to the middle - but it kept cracking in the same place. I'm sure that was mainly due to the weak repair job, but just wanted to make sure I was going in the right order. Definitely don't want to crack the new one - it was surprisingly difficult to track down. Thanks

Hey all - About a month ago, someone posted a link to great write up of how they upgraded their electrical system - bypassing some of the weak points in the stock set-up, additional ground points, etc. I bookmarked the link, but now ehn I try going back there, the page is gone. And I'm not having luck searching through the forums. If anyone can remember what I'm talking about, or has a valid link, that'd be great and I really appreciate it. Thanks.

Before you go to the trouble of tearing out the heater core, triple check all the connections. I learned this lesson the hard way. I had the same problem you describe - turns out on mine it was small leaks in the engine compartment, on the hoses where the heater control valve hooked up. The system developed small pinhole leaks under pressure, and the coolant ran down the pipes to pool up in the passenger-side floorboard. Feel the rubber pad where the heater core comes out from the firewall. If it's saturated or slick from coolant, that could be a tell-tale sign the leak's around the HCV instead.

+1 what jaekl said. I occasionally had the 'mystery click' on my '86. I'd jiggle the battery wires, then it would start right up - but the clock, radio presets, etc would be reset. On mine, turned out to be a cracked/stretched negative terminal that wasn't making good contact with the battery post. Track your cables and check/clean/tighten every connection.

No probs, man. Glad to help. Here's a good electrical fan write up for the 4.0: http://comancheclub.com/forums/viewtopic.php?t=8342 On mine, I just picked up one of those Hayden universals from AutoZone when they were having a sale. 14" and came with all necessary hardware/wiring. IIRC, the set-up cost me about $60. I removed the 4 bolts to remove the old fan off the water pump pulley, and pulled out the old shroud. Mounted the new fan as a puller behind the radiator - plenty of space, no clearance issues with the 2.5. I have an aux fuseblock mounted under the hood, coming off the battery (I use it for the stereo amp & a few other accessories) so that's where I wired it for power & ground. Mine came with a thermostatic switch on/off that clamped into the radiator, and an optional wire turned the fan on whenever the A/C was running - no A/C on mine, so I ran that wire to a rocker switch on my dash to control the fan manually as well (usually just play it safe and run it full time if I'm in-town or stuck in traffic). Been running it for about a year now, and it's worked great. Also - I wanted to echo what the posters above me said about exhaust. 2.5" or more is probably way too big for the 4-banger. I made a typo in my previous post - my exhaust is 2.25" (2 1/4), NOT 2.5. Sounds like you have a good exhaust set-up on yours already. :cheers:

I have an '86, 2.5, 4sp, mostly stock. Same set-up as yours. Unfortunately, there just isn't much available for the old Renix TBI set-ups (I had to go on a wild goose chase just to get a replacement injector) My suggestions: 1. Ditch the mechanical fan for an electric one. Bang for your buck, that's probably the best upgrade. Makes a noticeable difference in power. 2. Sounds like your tire size might be big. Stock is 195/75R/15 - each P-metric step up from that adds about .5" to your overall tire diameter, affecting your final drive ratio. Smaller tires but will help maintain higher power at cruising speeds. If the truck sees mainly road use, consider dropping tire size. When I got my Comanche, it was fitted with 235's - and going back to the stock size made a big difference in drivability. 3. Free up the exhaust and let the engine breathe. Personally, I run 2.5" pipe w/ a Magnaflow hi-flow cat & Gibson oval-style (it was a tad more expensive than the Flowmaster, but IMO worth it because it isn't quite as loud and had a lower tone - so it doesn't sound like a ricer). You can cut the cat out if you want - but IMO it won't make much of a difference, and might even do more harm than good. Even if you free up the exhaust, you want to keep a little back-pressure in the system to maintain low end torque. You can pick up a quality hi-flow universal cat for about $50. After the exhaust, check your options for a better intake. IMO, cone filters & power tubes aren't worth the money, because you're limited by a relatively smaller throttle body anyways, and most of them just wind up sucking hot air in from the engine compartment. Just drop an AirHog or K&N in your stock airbox, and you're probably good to go. That's pretty much it as far as cheap, easy options go for the older 2.5 TBI's - and that's how I have my truck configured. I use mine as a daily driver and work truck. I drive like a grandma (don't have much of a choice), but I have plenty of power for my needs. I get low-to-mid 20's mpg in mixed driving and occasionally the high-20's when I have a lot of highway miles. I'm in Washington State so I deal with a lot of climbing/mountain passes. With the smaller tires and few power upgrades, I can usually maintain speed (60-65mph) on all but the steepest grades - but I still occasionally have to downshift to 3rd on a few. Like was said earlier - the 2.5 probably needs to be matched with the 5sp and a re-gear to have the best drivability. When I save up the money/parts, that's going to be my next (and final) upgrade to my truck. No matter what you do with the 2.5, "there's no replacement for displacement" It's always going to be a dog. The only thing appealing about it is the mpg - but even then, it's not like we're talking about a miserly +35mpg engine, it simply has to work too hard to put up great economy numbers. You start throwing big tires and a lot of weight on the rig, and suddenly the 2.5 is giving you mileage in the teens. I've known guys with stock XJ's & MJ's with 4.0's and manuals that drive them efficiently and get numbers that are only 2-3mpg's off what the 2.5's get.

I don't think it's the indicator light. I have an '86 2.5, 4x4 - that connector is hanging blank on my truck too, and my indicator light works. What colorts are the wires going to the connector? I can't really make them out in the pictures, Looking at my wiring diagram .... my guess is it's un-used spot for the A/C clutch relay. or possibly for the EGR solenoid?

My '86 had the 4x4 emblems on the tail end sides of the bed, just about even height with the top of the tail lights. But I don't know if the factory switched locations at some point in time, or if mine were added on by a PO.

+1 on the electric fan. Bang for the buck, that's probably the easiest way to squeeze extra power/economy out of the 2.5. Letting the engine breathe better with a hi-flow exhaust and/or intake helps out. Best millage out of the 2.5 is relative, and depends on what you want to use the truck for. Running the stock tire size (205/75/15) doesn't look nearly as cool but will increase your mpg and give the truck the guts it needs at highway speeds, and to keep from having to downshift on any hill you approach. So for a truck that sees mainly highway miles, the 2.5 is going to be economical. But for building a trail rig, the 2.5 isn't going to give you significant savings over a 4.0 (maybe 2-3mpg) because it simply has to work to hard to turn the gears & taller tires. The best thing you can do with a 2.5 is just keep it well tuned & maintained with quality stock parts. Make sure the MAP & O2 sensors are good and that you're getting the right fuel mix. Check the vacuum lines for any leaks. The Renix ignition system works best with standard copper plugs, a set of quality wires, and brass terminal cap & rotor. Spending the extra for platinum plugs or performance wires doesn't make much of a difference, and some people have reported that it can slightly decrease economy I use my '86 2.5, 4spd as a DD, so have it close to stock. I run an electric fan, 205/75/15 tires, 2.5" exhaust with a hi-flow cat & oval Gibson muffler (tad loud but not ricey), good cap & rotor with a premium wire set from NAPA. No AC or Power steering. I've averaged high 20's (25-28mpg) with mixed driving/more highway miles. But honestly, I drive like a Grandma. If you really want to squeeze every mpg out of your truck - a good trick is to T a cheap vacuum gauge into the pcv system and mount it on your steering column. The engine generates higher vac pressure at lighter loads, so by watching the gauge, you get a feel for the most "economical" way to drive it.

Here's another good resource: http://www.4btswaps.com/forum/index.php

thanks for the warnings, guys .... good to know.

Hey guys - thanks for the tips ... especially the link over to 4bangerjp.com - lots of good info over there. Especially in this thread: http://4bangerjp.com/forums/index.php?topic=3563.0 I had to jump through a few hoops (the supplier sent the wrong part twice, and then sent an empty box before finally getting it right.) but I eventually got a replacement injector. Just to let you know what I found out through research and talking with the guy at the parts store: - The Jeep TBI's are identical in fit, size & appearance to the standard GM-style TBI's from the 80's-early '90's. But they are a unique flow rate, and therefore don't cross-reference to any GM applications - The flow rate for the 2.5 Jeep injector is just in between the GM Injectors for the 4.3 V6 and the 5.0 V8. (according to test results the poster at 4bangerjp.com got, the Jeep is 48lbs, while the GM 4.3 V6 is 47lbs, and the GM 5.0 V8 is 50lbs) Of course, the big difference is that GM injectors are a dime-a-dozen at junkyards, in stock at most parts stores, and GM ones can cost significantly less simply because of better availability and bigger market. I had to go ahead and get my truck running quickly, so I just dropped in the Jeep injector. But I think for my next project, I'm going to fab up a TB spacer, swap in a GM 5.0 Injector, and see if that combo gives any slight boost in performance.

I need to replace the injector on my '86 2.5 TBI. After looking around, I've found my options are $80 for a reman unit from the injector shop in town or $200 for a new unit from NAPA. The parts dept. at the Jeep dealer lists the OEM unit as discontinued. I've read how the MPI guys can use Ford injectors to get a boost in performance. Is there a similar mod for the TBI? An injector from some other vehicle that will fit and give a little better flow & spray pattern? (and maybe even be cheaper/more available?)

sorry 'bout that, brig - I just speed-read the ISA stuff and printed it out. Didn't realize you answered my question 'till I was out in the garage. :oops: Anyways, injector measures <10ohms ... so it's off to the parts store. Thanks again for your help.

thanks, that's what I figured. Just to be specific - what's happening with mine is: No leaks when engine is shut off. When engine idles, there's a small consistent drip from the bottom of the injector into the bore When I depress the throttle, the drip just stays about the same - there's no noticeable spray. I assumed that's bad - but I just didn't know if that was the symptom of some other problem (such as bad pump or pressure regulator)

thanks a ton for the info, brigarpeon & pete. I'm headed back out to the garage this evening. One clarification, though - when you say injector shouldn't drip when off, do you mean when engine is shut down, or simply at idle? Also, is there a way to test the injector itself to see if it's good? Sorry about the noob questions ... but this is the first FI'd vehicle I've ever worked on myself.

So my pressure's actually not off too bad? I had read psi was supposed to be 14-15 so figured 10 was way too low. I was also suspecting a bad injector ... at idle, the injector basically drips, drips, onto the plate, but when I apply the throttle I can't see any spray ... but I just thought that was a symptom of low fuel pressure. How do I test the injector? thanks for the tips & info.

cool. Thanks for the info, guys. Looks like I'll have to stop cutting corners.

Honestly, I'm puzzled about it. The truck doesn't see any hard off-road use - it's a DD. I dunno if I've just had a run of bad luck or what - one pump was a junkyard pull, so I sorta expected it to fail. The last two have been cheapo remans. I do use cheap gas on occasion ... but I don't think that's what's killing them. Last time I dropped the tank (about a year ago) the inside looked good, and the sock was clean. The grounds are good. About a year ago I replaced the wiring/sockets in the taillights and cleaned/replaced the ground in the process. (I also checked 'em again this time after reading threads on the issue). I'll clean the tank this time ... but I'd like to avoid a swap if possible. I have the extra large MJ one, and I like the extended range for road trips.

I have an '86 2.5 TBI. Bad drivability issues right now (won't idle - bogs & sputters under load - smells rich, flooded) Checked the usual sensor culprits - MAP & TPS test fine. New fuel filter. Blew out the vacuum lines & checked for leaks. Compression test is good. New cap & rotor, plugs, wires. Cat & muffler are 3 months old. Installed a fuel pressure gauge into the test port on the TB, and I'm getting about 10psi max. Tried adjusting the regulator, no luck. Pinched the return line, no spike in pressure. So I'm thinking the fuel pump has either sucked up crud and is blocked, or it's going bad. I'm going to drop the tank and pull it. Now - if the pump has gone bad, this will be the 3rd pump it's gone through in a little over 3 years (and they all managed to go just after the warranty is up) As any MJ'er knows, finding replacements is a headache, and they've got expensive as well. So ... is there a relatively easy way to switch to one of those cheaper universal electric pumps that mounts outside the tank, and still keep a functioning gas gauge and stuff? Anyone know of any good write-ups for it?

Yup. I just installed a Supertach II on mine a few days ago. For a Renix 2.5, the green splices into the green/white coming off the ICM. I already had the cluster with gauges ... but no tach (giant fuel gauge with warning light/AMC logo at bottom left instead). The tach cost me $20, and I probably could've found a full cluster at the JY for the same price ... but I didn't feel like tearing my dash apart again after finally fixing the rattles. Plus, I just like rockin' that old AMC logo on my dash

If you're looking for a "close enough" fit, the 80's box-style S-10 are probably your best bet - both the long & short bed seem to be the closest to the MJ. Just be sure to measure. I have an '86 long bed, and the shell on mine came from an '85 long bed S-10. It's not a perfect fit. It's the right width - but the roofline's about 4" higher than the cab and it's just a couple inches too short. But it works for me because it has full panel doors on the back, and I don't have a tailgate. Plus I couldn't beat the price (free) If you want an exact fit, check out your local canopy store. The basic aluminum shells are kits, and the shop has to custom cut & fit them to your vehicle anyways. So if you get one of those, everything should line up. Before I found my used one, I checked out a couple places, and was quoted around $400 for a new, custom fit aluminum one.