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Learn the noob some Renixeses!

JeepNoob

NAXJA Forum User
Location
Pueblo, Colorado
Hey guys, looking at getting into another XJ. (finally!) It's a 30-year old death trap, but at least it has a 4.0 and 4x4, and it's being sold for a price that's an absolute sore-dick deal. Few problems (of course it wouldn't be a cheap Jeep if there wasn't some) 1. Owner says it idles high. I dunno how he figures that since it's an automatic with no tach. He said it has something to do with some throttle lever or linkage hitting the steering shaft. Yeah, I have no idea either, I'll have to take a look at it, but apparently it does run and drive. 2. 4x4 doesn't work. No big deal for a street-beater. I think the two problems may be related...

Now, I'm pretty good and knowledgeable with 4.0's and XJ's in general, but a Renix is kinda new territory for me. Some thoughts I had-

1. Common problems. I know about a lot of the common 4.0 stuff like oil leaks, header cracks, CKP sensors, etc. What on a Renix is different from a H.O. that will bite me in the fourth-point-of-contact and leave me stranded or with a vehicle that runs like crap?

2. Differences? I know about the EGR, fuel pressure regulator, head/intake manifold/cam/ignition coil. Anything else I should know about?

3. EGR delete? Worth it or no?

4. 96+ stud girdle? This thing definitely seems to help 4.0's live a long, healthy life. Could one be swapped into a Renix? I'm sure this thing will have a rear-main leak, so if I'm going through all that work, might as well throw one in if I can.

5. Vacuum leaks on a Renix? I suspect problem 1 and 2 may be related...

6. Good stuff to do. Mods, preventative maintenance, etc. What would be some good things not listed to make sure this thing lives a long, happy, efficient, trouble-free life?

I have a Chilton manual for XJ's and access to Mitchell ProDemand, a few FSM's, plus the search button, so I'll try to keep the stupid questions to a minimum, but any input is appreciated.
 
High idle could be caused by a vacuum leak, coincidentally, the 4x4 actuator motor on the front diff is vacuum driven......
Dont waste your time w aftermarket tps or cps.
 
Most common issues are old, clogged injectors, bad MAP hoses, burned CPS wires, vacuum leaks, hose between fuel pump and housing and fuel pumps. Depending on age, the water pump is probably getting old, as well as the slip rings and bearings in the alternator.
 
Hey guys, looking at getting into another XJ. (finally!) It's a 30-year old death trap, but at least it has a 4.0 and 4x4, and it's being sold for a price that's an absolute sore-dick deal. Few problems (of course it wouldn't be a cheap Jeep if there wasn't some) 1. Owner says it idles high. I dunno how he figures that since it's an automatic with no tach. He said it has something to do with some throttle lever or linkage hitting the steering shaft. Yeah, I have no idea either, I'll have to take a look at it, but apparently it does run and drive. 2. 4x4 doesn't work. No big deal for a street-beater. I think the two problems may be related...

Now, I'm pretty good and knowledgeable with 4.0's and XJ's in general, but a Renix is kinda new territory for me. Some thoughts I had-

1. Common problems. I know about a lot of the common 4.0 stuff like oil leaks, header cracks, CKP sensors, etc. What on a Renix is different from a H.O. that will bite me in the fourth-point-of-contact and leave me stranded or with a vehicle that runs like crap?

2. Differences? I know about the EGR, fuel pressure regulator, head/intake manifold/cam/ignition coil. Anything else I should know about?

3. EGR delete? Worth it or no?

4. 96+ stud girdle? This thing definitely seems to help 4.0's live a long, healthy life. Could one be swapped into a Renix? I'm sure this thing will have a rear-main leak, so if I'm going through all that work, might as well throw one in if I can.

5. Vacuum leaks on a Renix? I suspect problem 1 and 2 may be related...

6. Good stuff to do. Mods, preventative maintenance, etc. What would be some good things not listed to make sure this thing lives a long, happy, efficient, trouble-free life?

I have a Chilton manual for XJ's and access to Mitchell ProDemand, a few FSM's, plus the search button, so I'll try to keep the stupid questions to a minimum, but any input is appreciated.

1) Renix is fine and simple.

2)Again, simple. CPS can be tested and modified easily. http://cruiser54.com/?p=50

3)EGR delete is fine.

4) Stud girdle is a waste of time. It was an attempt to keep noise/vibration/harness down only. Had nothing to do with longevity.

5)http://cruiser54.com/?p=121

5) www.cruiser54.com. Complete tips 1 through 5 right away.
 
Tampering with emissions controls like EGR delete is illegal by Federal law (Clean Air Act). If you are subject to emissions testing and inspection (like we are in CA), you won't pass.
 
Tampering with emissions controls like EGR delete is illegal by Federal law (Clean Air Act). If you are subject to emissions testing and inspection (like we are in CA), you won't pass.

Aware of that. Don't plan on ever living in a Nazi-state like California. (no offense) One guy here (pacifically 5-90) has found some interesting results that seem to indicate that the EGR on the Renix has absolutely no effect whatsoever on it's intended function (reducing NOx emissions) but does have a beneficial effect on reducing HC and CO emissions- https://www.naxja.org/forum/showthread.php?t=937076

Thanks for the replies all, cruiser54's responses and write-up especially. That's the kind of stuff I'm looking for! After dealing with the throttle linkage on this thing (long story, don't ask, I got it for dirt cheap because of that) and looking at the mess of vacuum lines, wires, etc. in the engine bay, I think this thing is just BEGGING for an HO swap. Or the top end, at least. The rest of the Jeep though, it needs some lovin' for sure, but again it was dirt cheap. I don't normally go for doo-dads in vehicles like power locks, doors, windows, automatic transmissions, a "power/comfort" switch for the transmission on the dash, etc. Maybe it's just because they're wrapped up in an XJ, but they're starting to grow on me lol. I'm now kinda thinking about turning this Jeep into a resto-mod, a few modern touches from some later-model XJ's here and there, wrapped up old-school red with chrome trim glory!
 
Aware of that. Don't plan on ever living in a Nazi-state like California. (no offense) One guy here (pacifically 5-90) has found some interesting results that seem to indicate that the EGR on the Renix has absolutely no effect whatsoever on it's intended function (reducing NOx emissions) but does have a beneficial effect on reducing HC and CO emissions- https://www.naxja.org/forum/showthread.php?t=937076

Thanks for the replies all, cruiser54's responses and write-up especially. That's the kind of stuff I'm looking for! After dealing with the throttle linkage on this thing (long story, don't ask, I got it for dirt cheap because of that) and looking at the mess of vacuum lines, wires, etc. in the engine bay, I think this thing is just BEGGING for an HO swap. Or the top end, at least. The rest of the Jeep though, it needs some lovin' for sure, but again it was dirt cheap. I don't normally go for doo-dads in vehicles like power locks, doors, windows, automatic transmissions, a "power/comfort" switch for the transmission on the dash, etc. Maybe it's just because they're wrapped up in an XJ, but they're starting to grow on me lol. I'm now kinda thinking about turning this Jeep into a resto-mod, a few modern touches from some later-model XJ's here and there, wrapped up old-school red with chrome trim glory!

HO swap isn't necessary at all. The stuff you mention can be brought back to stock simply and inexpensively.

Here's something for ya to read:

HO myth buster


Renix in 90 made 182 HP. HO in 91 made 190 HP. That's 8 HP difference.

HO only made more HP than Renix at higher RPMs and not a bit more torque. HO had a 58 mm throttle body versus a 52 mm throttle body on a Renix. That’s 20% more air available through the HO throttle body. The HO also had a better design header. See where I'm going with this?

It’s only a 4% horsepower increase…..

The whole 8HP was not mostly from the head, but from the bigger TB and better exhaust manifold.

Put a 60mm TB from www.strokedjeep.com on your present manifold using the Renix head, eliminate the "crush" in your headpipe with proper re-routing, and go for it.

HO stands for Highly Overrated.
__________________
 
Welp, cruiser54 is gonna be upset about this... The new XJ might have a later model H.O. short block in it. While doing some work on it today including replacing the thermostat in it (with as cold as it was running, I was amazed it even had one in there. MotoRad Advance/O'Reilly's 160-dungarees crap. Some people... Replaced it with a 195 NAPA Premium unit.:cheers:) and cleaning electrical connectors, I noticed a number on the cylinder head-looked like 0331, but I couldn't be sure, so I cleaned it off. Sure enough-0331, right where they put the casting numbers on the heads. Even looks like it has the bolt holes that hold down the later model coil packs.

I'll have to yank the valve cover (which is leaking) off and make sure I don't have any cracks, but how is that possible?! I was under the impression that Renix stuff couldn't be put onto an H.O. engine and vice-versa. Something to do with port-spacing and such...
 
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