Coyote

Installed the flowkooler water pump on my 1988 RENIX 4.0. Everything was straight forward, just like installing a factory water pump. After 30 mins of running I had a slight leak at the bottom driver's side corner. Retorqued the mounting bolts and everything was good. A word of caution; this pump does flow more than a factory unit and will create higher pressures in your cooling system. That's good for getting out air pockets and general cooling, but not good if you have old hoses, bad connections or a weak radiator/heater core. I replaced all of the hoses just as a precaution/general maintenance and was installing a new radiator at the same time anyways. I've only had it operational for a few days, but I've been running it pretty hard doing 0 to 60 tests. It holds rock solid temps whether I'm running it hard or idling in the drive thru. I'm not sure if the improvement was due to the flowkooler pump, new radiator and hoses or the electric fans, but either way I'm impressed and ready for the scorching Georgia summer.

I have LED headlights (actually ALL internal and external LED lights), but I've never seen ones with turn signals built in. That's great! Where did you get them? I'm assuming you tapped into the factory front turn signals for power. Are they actually both white and amber (I assume the turn direction) or was that just for advertising purposes?

Write up in DIY section under MSD ignition on 4.0 RENIX. Let me know if I missed anything.

I recently installed a MSD Street Fire and remote coil on my 1988 Comanche 4.0 (RENIX). It decreased my 0 - 60 times by 1.5 seconds (yes, that's right...19% improvement), smoothed out the idle and improved the throttle response and acceleration. Not sure if it improved the gas mileage, I've been having too much fun with the new found power to tell. I did the mod at the same time I replaced the water pump (high efficiency, supposed to decrease hp drag) and swapped my clutch fan for electric fans. So I'm not sure how much of the improvement is due to each individual component, but there is a significant improvement over all. This mod is for a 4.0 RENIX with the ignition module and all of my components were in working order (new cap, rotor, wires, plugs, ignition module; coil was operational but I suspect it was on the down hill slide). I'm not sure if the 2.5 engines use the same set up or if this will work on them. If someone tries this on a 2.5 please comment below. With all the disclaimers out there, here goes: You do not have to cut the factory wiring and all MSD boxes are wired the same; Configure your MSD box for 6 cylinder, cut the red loop Heavy black wire to battery neg (will probably have to extend the wire to reach the battery, mine was pretty short) Heavy red wire to battery positive White trigger wire (points/amplifier) to the ignition module negative coil terminal. You'll have to remove the factory coil from the module by unscrewing the two small torix bolts. If you are standing at the engine looking at the ignition module on the passenger fender, you want the coil contact on the left. You can solder the white wire directly to the contact (or make a small jumper wire). Small red wire (12+ keyed ignition) goes to the ignition module positive coil terminal. This is will be the coil contact on the right side. So the same as above and solder it to the contact (or make a small jumper wire). Orange wire goes to the actual coil positive (either a new remote mount coil or reuse the factory coil). Black wire goes to the actual coil negative (same as above, either new remote mount coil or reuse factory coil). Just for clarification all other wires are NOT used. The gray tach wire isn't needed. The violet and green wires (magnetic pick ups) are not used because the white wire (points/amp) is and you can't run both at the same time. The factory tachometer still works, the ECU advance timing is still functional and the MSD multi spark and rpm limiter work as advertised. The RENIX red lines at 5,000 rpm. I set my limiter at 4,800; low enough to keep the engine from red lining, but high enough you don't hit the rev limiter all the time. That's it, pretty simple. It worked best for me to mount the MSD box and remote coil high up on the passenger side fire wall. If you use a remote coil you'll need to make a new coil to cap wire. All of the factory spark plug wires are too short, but Advance Auto carries a single universal spark plug wire for about $15. In the pictures I relocated the ignition module to the passenger fender well close to the fire wall. This was just to make for an overflow bottle and is not necessary for the system to work. Special thanks to Grewsum 2Sum for the help with the wiring diagrams. Ignition module, left goes to white trigger wire, right goes to small red 12v pos wire. MSD box mounted upside down high on the passenger firewall. This way makes it easier to route the wires and easy access to the rpm switches. It doesn't matter how the box is mounted as long as water can drain out of it. Double check the location to make sure you can still close the hood. Take care not to accidentally drill through the air box, heater coil and a/c lines. The remote coil mounted high on the passenger side firewall. Make sure you can close the hood and don't drill into anything important inside. You will need to make a longer coil to distributor cap wire.

No problem. I'll see what I can do about getting something in the DIY section.

I don't remember the model number, but it's the Summit brand 55k volt one (about $50). You can do the MSD box with the stock coil if you want. Just have to flip the coil to the side and bolt it back into the ignition module, sort of hanging in the air off of the right side (towards fire wall). My coil was the factory orginal and questionable maintenance history so I just went ahead and replaced it. I have no idea how that thing managed to last this long, but they must of used some pretty decent quality parts at the factory. Lol BTW with the coil on the firewall the coil to distributor wire is too short. Checked the old plug wires and none of them are long enough. Ended up using a single universal speak plug wire from Advance Auto ($15 in stock in most stores). I would have liked a black one for a more subdued/factory look, but the red was all they had at the time.

No problem, glad it helps. Once I got the wiring figured out the rest of the process was pretty easy. It only takes a little less than 2 hours to relocate the ignition module, mount the MSD box and coil, make a new coil wire and wire everything up/put it in looms and zip tie. The hardest part was soldering new leads to the ignition module coil contacts. I would have liked to completely by pass the ignition module, but I couldn't figure out a way to do it. The ECU uses the ignition module to control the timing advance functions and I don't think there's a way to get around that. Good luck and I hope the ignition upgrade works as well for you as it has for me.

I ran a '91 XJ with 5" of lift, 31s and front and rear LockRights for about 10 years. That thing was a beast off road. The traction was incredible and the auto made it real smooth to control. I could do stuff guys with bigger tires and better axles couldn't do. Probably because I could just leasurly cruze through things other people had to hit full throttle. As great as they were off road, the LockRights were miserable on the street. I didn't mind the clicking and banging, but the torque steer was horrible. Accelerate and it pulled one way, decelerate and it goes the other. It was real easy to do accidental lane changes if you weren't paying attention.

TJs, XJs and MJs all use the same basic front axle, control arms and steering design. Any time you start going more than 3" of lift on them it messes up the geometry. You need to do things like adjustable control arms, drop pitman arm, offset ball joints, etc to correct the steering. I don't know of a way to lift more than that without causing steering issues. The rear end is a whole different animal. It's pretty easy to lift the rear without effecting the steering too much. New lift springs, add a leafs, extended shackles or a spring under conversion will get you the height without causing too many issues. I used a '91 XJ with 5" of lift and 31s as my daily drive for about 10 years. Trust me after the first day you'll want to use one or more of the above options to fix the steering issues.

Got to do some 0 to 60 testing on the truck today. Had a hard time keeping the tires from breaking loose and squealing which should say something about the improvement in power. If I had a perfectly straight, level, dry strip of road with good tires I'm sure it would do better. For now, it was a 1.5 second decrease in 0 - 60 times (previous best 7.77, current 6.27). Won't be able to tell if there's any mgp improvement until I get done messing with 0 - 60 tests. Lol I also replaced the clutch fan with electric fans and a high flow water pump (supposed to be less hp consumption) all at the same time. Not sure how much was due to that vs the MSD box and coil, but either way I'll gladly take a 19% improvement. It was definitely worth the time and money to me. 😁

Nice truck. You're just a little north of me I'm down in Warner Robins area, but go up to ATL often. If you need anything hit me up.

Just swapped out my radiator and clutch fan with an all aluminum radiator and 3 electric fans this week. The 2 plugs on the front driver's finder next to the head light are factory wiring for the electric a/c aux fan power and the temp sensor. The sensor plug is not suitable for powering a fan. The fan power plug one is fine for 1 electric fan, but can't handle the draw for 2 or 3 fans and will eventually burn up. Much better to add a relay with separate battery cables for the other fans. BTW a '96+ thermostat housing already has a threaded temp port built into it. Made it much easier for me to use a temp sensor there, connected to a relay, ignition keyed +12v and pos/neg cables from the battery to the fans.

Just did this last week in my 1988 Eliminator. Used an Oz cooling all aluminum 3 core radiator and 3 electric fans (Amazon $220). I had to notch the top support for the filler neck and reuse the isolation pads, but I was pretty easy. Also took the opportunity to swap in a Flowkooler water pump and convert heater to '97+ style. You'll need upper and lower radiator hoses for your year, heater in/out hoses for '97+ Cherokee and the water pump return coolant tube for a '96+ Cherokee. The tranny cooler tubes and aux a/c fan sensor fit and didn't require replacement. Whole project is pretty straight forward, other than the fan wiring diagram. Throw that crap in the garbage and fine a good diagram on line. Took a two days at a very leasurly pace. Much better now.

Thanks. The stock ignition was ok, nothing major wrong. It was getting hard to start, idle was a little rough and acceleration didn't seem quite right. I'm pretty sure that was the original coil and it was on its last leg. I was converting from a closed cooling system to a 97+ open cooling system and needed to relocate the ignition module and coil so I could put a factory '96 XJ radiator overflow bottle there. Still not completely done with the conversion yet, so I've only cranked it up a few times, let it idle, played with the acceleration, ect. Should be all done and back on the road again by this weekend. I can give a more definitive answer on exact improvements then. In the meantime it does start much easier, idles smoother and the throttle response seems better. If you have to buy everything new, total cost for the MSD Street Fire, coil and extended coil wire is less than $250. I already had the MSD Street Fire from another project and was planning replacing the coil anyways so it was worth it to me. After I drive it for a bit I can post the 0-60 and mpg improvements (if any) so you can decide if it's worth it to you.

Finished product. Ignition module relocated to passenger finder by fire wall (to make room for '96 style radiator overflow tank). MSD Street Fire and coil mounted on fire wall. New coil to distributor wire. All connections soldered, shrink wrapped and put in wire loom.

Forgot to add; MSD box organge wire to new coil + and black wire to new coil - Config box for 6 cylinder (cut the red loop) All of the other wires (gray tach, violet & green mag pick up wires) are not used.

SUCCESS!!! The MSD Street Fire is connected to the RENIX 4.0 and operating as advertised. The factory tach still works, the MSD rev limiter works and it's getting multiple sparks per cylinder. Unfortunately there's not a way to completely bypass the ignition module as far as I can tell. Many thanks to Grewsum 2Sum for his instructions. For anyone else that wants to do it here's how to wire it up (all MSD boxes use the same wiring): Heavy red - battery + Heavy black - battery - White wire (points pick up) - the - side coil connection in ignition module Small red wire - the + side coil connection in ignition module (supposedly also works spliced to yellow plug wire too, but didn't try) Pic to clarify. Ignore my crappy wiring job, just temp mounting to ops check it. I'm cleaning up the wiring and putting it in loom now. Haven't road tested it yet, but it starts up better, idles smoother, better throttle response and appears to have more power. Still finishing up installs on the closed to open cooling system and 97+ heater conversion. I'll check mpg and run some 0 to 60 times this weekend to see if there's any improvement.

No luck on getting the MSD box wired up. BTW I messed up the above diagram; heavy red to battery +, heavy black to battery -. I played with the wiring for about 6 hours. Tried disconnecting the ignition module and wiring from those plugs (violet/green and White; not both at the same time). Tried it from the distribution (with and without ECU connected). In desperation I tried it off of the - + coil connections in the ignition module. I was able to use a remote mount coil (the way I'll leave it configured for now), but wasn't able to get the MSD box to fire. Strange considering that's how I wired my '91 Cherokee 4.0. Basically just used the coil wires as magnet pick ups for the MSD box. At any rate I'll settle for a remote mount coil and use the MSD box on my '96 Cherokee. If anyone figures out how to wire a MSD box into a RENIX 4.0 please share the wealth.

Thanks. I know the ignition module has to be bypassed, just wasn't exactly sure how to do it. I know I'm not the first person to put a MSD in a RENIX, but not having any luck finding writeups or pics. Lol

Forgot to add you'll need the ECU and TCU as well. Basically you'll just be using your Comanche for the frame and body, everything else will be Cherokee. The 4 door Cherokees use the same front doors as Comanches, basically a one for one swap (great time to upgrade to electric locks, windows and mirrors).

It depends on your definition of difficult. All engine swaps are not going to be fun, quick or easy. BTW you'll have to swap the tranny as well. If you're going through all that trouble I'd go all out and take a '91 -96 Cherokee 4.0, AW4, transfer case (hopefully a NP 242, but a NP231 will work too), front and rear axles, wiring harness and instrument cluster. '91 and up are 4.0 HO years, OBD II started in '96 (probably the best year). '97 and up use a different instrument cluster that won't just bolt in.

Found a pin out for the ignition module. Starting at the far left (closest to radiator) It's connector No1 C(Tach) B (Grounding-) A (Ignition +) connector No2 B (ECU Square wave input ignition coil interface) A (Blank) connector No3 C (Blank) B (Blank) A (Blank) Going off my best guess according to the MSD Street Fire instructions I think the box should be hooked up like this: Heavy Red (Battery -) Heavy Black (Battery +) Red (switched 12v+) - connector No1A Orange (coil +) - connect to new coil Black (coil -) - connect to new coil Violet (magnetic + coil input) - connector No2B Green (magnetic - coil input) - connector No1B Gray (Tach) - connector No1C Does that look correct? Or should I be using the points/amplifier (White) connection?

I'm getting ready to put a MSD Street Fire in my '88 4.0 Comanche. Years ago I put a MSD 6A in my '91 4.0 Cherokee and really liked it. Pretty straight forward install and didn't take very long to do. BUT that was a HO engine, totally different wiring than a RENIX. Has anyone put one in a RENIX with that weird ignition module under the coil? Any tips on how to wire it? Coyote

I've heard good things about Black Magic brakes, but have never personally used them. I'll have to check them out. If I wasn't trying to keep the original rims I'd be all over one of the big brake packages.

Thanks for the info. I'd like to have the big brake upgrade, but all of the stuff I've looked at (Wildwood, WJ knuck swap, Terraflex, etc) says they need 16" or larger rims. I'm trying to stick with the original 15" Eliminator rims so the big brake stuff is out for me. The newer style (91+) brakes with drilled and slotted rotors has done very well for me in the past. If I can get away with just swapping everything from the knuckles out I should be in pretty good shape. 😁