Renix?

I have only owned my Jeep for about 5 months, I am just wondering what RENIX means, I have a 1990 XJ 4.0 4WD AW-4 and i've heard of the early XJs refered to as RENIX. What does this mean?

Renix refers to the fuel injection/computer control system on 87-90 4.0 liter engines. It was replaced in 91 with the high output engine, refered here usually as HO. 173 hp vs 190 hp.

Lots of different sensors and such between the two. That's why you will want to state what year and engine you have whenever you post, so as not to annoy the cognicenti (old farts).

Renix is a reflection of the fact that the French owned a majority stake in AMC back in the 80s. The 'computer' controlling the fuel injection on the 87-90 4.0L engines was made by Renault and Bendix; Renault + Bendix = Renix...

ok kevin, I resent that remark.

Yucca-Man said:

The 'computer' controlling the fuel injection on the 87-90 4.0L engines was made by Renault and Bendix; Renault + Bendix = Renix...

Click to expand...

You learn somethin new everyday. I did not know that, now I can go impress my friends.

Yes, the RENIX ignition system was used on the 87-90 4.0 engines. Remember back to the days of American Motors Corporation (AMC). In the 80s a French car company who's name started with Ren... owned a large percentage of AMC, I believe it was 40% but I may be wrong. Just for the record Ford owns 40% of Mazda.

Since "that" car company basically had controlling interest they introduced a lot of their technology. We also see this in Mazda vehicle, lots of Ford Technology.

AMC came out with the XJ using the resources of the French company. There was an article on which talked how AMC used the French companies computers to do finite element analysis of the 1984 XJ chassis. I also read that GM could not supply enough V-6 engines so AMC dusted off the straight 6 engine but the auto industry was going to fuel injection. AMC decided to go with fuel injection most likely to meet Federal Emissions standards. The French company teamed with Bendix to design a system. Renix is a contraction of the two companies names: RENxxxx + bendIX = Renix.

The Renix system does have a knock sensor to retard the timing if you have engine knock, the Chrysler system used 91 and later does not have a knock sensor. I have seen countless posts about HO people complaining they have to run mid grade fuel to avoid ping. So that saving you at least 10 cents/gallon.

Most people today forget that AMC made vehicles. AMC was an interesting company, they some how ended up using a lot of good components. The AW4 transmission never was replace by a Chrysler transmission. I am told the AW4 is a copy of an old Ford transmission but with the problems fixed. AMC also used Dana axles. There will be discussion about Dana 35 vs Chrysler 8.25 but AMC used only Dana axles in the XJ. I have talked to several mechanics and they all say they'd take the Dana 35 over a Chrysler 8.25 any day. This is the OEM board if you want to talk about spline counts and larger tires then talk on the modified board.

I will say Chrysler does support most of the parts I need for my 88 XJ, but like any corporation they try to use "corporate" parts. In my opinion this took away some of the "JEEP" engineering. AMC did not have enough engineers to value engineer all the margin out of parts so there is a lot of robustness in the AMC/Jeep designs. I think this policy to use corporate parts has taken away the quality that made Jeep a Jeep.

You have a unique XJ in a 90, is still mostly the AMC design. The Chrysler engineers had not had much time to make it "corporate".

The main difference between the Renix and HO engines is the cam shaft. The marking department got the engineers to change the cam so they could advertise more horse power. I believe the Renix is 177, HO is 190HP. By giving in to the marking guys they gave up low end torque. I have never driven a HO XJ but I know my XJ will idle at 800 rpm and pull itself down the road at 7 mph, even pulls it self up grades, all without touching the gas pedal.

kevin s said:

Renix refers to the fuel injection/computer control system on 87-90 4.0 liter engines. It was replaced in 91 with the high output engine, refered here usually as HO. 173 hp vs 190 hp.

Lots of different sensors and such between the two. That's why you will want to state what year and engine you have whenever you post, so as not to annoy the cognicenti (old farts).

Click to expand...

As the official resident Olde Pharte, I feel a duty to point out that there are many differences between and among different years of XJ, not solely whether one has a Renix model or an "HO" model. It is always a good idea to mention what year, engine, and transmission you have. It's not so much a matter of annoying anyone (old farts, young farts, or middle aged farts) -- it's a matter of wasting a post, because without knowing what equipment your Jeep has, it's often impossible to even begin to answer the question.

Unfortunately, a lot of people lately seem to assume that all XJs are created equal, so they start tossing out answers that might be correct for their particular year but which may be totally irrelevent for the vehicle in question.

Eagle said:

Unfortunately, a lot of people lately seem to assume that all XJs are created equal, so they start tossing out answers that might be correct for their particular year but which may be totally irrelevent for the vehicle in question.

Click to expand...

Yep. My point exactly. I've been an old fart my entire adult life, so I speak from experience. Ask my kids.

I had an '84 Renault Encore for 145,000 miles and 17 years. The manual window cranks were the EXACT SAME part as on my first XJ, an '87. Lots of sharing in those years. arty:

Are a Renix block and a H.O. block interchangeable? I want to build a stroker at some point before to long I know that the heads are diffrent but the H.O. head should be able to be swaped over i would imagen. Will the diffrent sensors be able to bolt up to the block?

Fenton Beech

My 87XJ motor is broke and I may buy a 102k mile 4.0L from a 91 (HO I guess).

I am thinking of upgrading the injector system at the same time. I can get harness and ALL electrical components and install them but have one question;

What should I do about the CPS? Will the 91 cps bolt to my 87 bell housing? If not should I use the 88 CPS or is there an adaptor.

Please email me since I have not been able to get replys to any of my messages I have left on this board. I obviously don't know how to work this crazy thing.

[email protected]

i find it amazing that the same company that builds the 4L I-6 that i love so much is the same company thats responsible for the pacer

Bilbo,
You can just swap in the motor itself. I think you will just need to adapt the cooling system. Look as Cherokee America's website. Also look at this article for TB adaptation: http://www.rockmodified.com/2003/april/TB/tb_perf.htm

Also, the Pacer is cool, sort of looks like a Porsche 911 don't it?
Tom

martin said:

The main difference between the Renix and HO engines is the cam shaft. The marking department got the engineers to change the cam so they could advertise more horse power. I believe the Renix is 177, HO is 190HP. By giving in to the marking guys they gave up low end torque.

Click to expand...

Last I checked 87-01 all had the same cam.

There have been posts on here showing where the torque curve peaks on the 4.0 engine. My 88 XJ had a 2400 or 2500 rpm peak, while the later ones were closer to 3000 rpm. Prehaps the aftermarket guys sell the same cam for all years but I'd check with the dealer parts guy to make sure.

Prehaps if you do a search on here for torque curve peak or a smililar phrase you will find that data.

Just on the topic of Renix engines, why are 87 4.0s listed as 173hp and all other newer Renix 4.0s (88-90) listed as making 177. Did they change somthing to add 4 hp, or did they just re-test the engine? I've been trying to find out for years why mine is only rated at 173. Also torque for 87s is listed as 220 and 88 and up is 224.

martin said:

The main difference between the Renix and HO engines is the cam shaft.

Click to expand...

JJacobs said:

Last I checked 87-01 all had the same cam.

Click to expand...

Both wrong. The main difference between the Renix and HO are the computers, throttle body, (HUGE difference here) intake, and exhaust manifold. I think the cam from 90 and 91 are the same, if not exactly the same they are very close. Renix torque peak is around 2400, 91-95 HO is around 4000. In '96 they used a dual pattern cam, lowering the torque peak to 3000. I wouldn't say a Renix has more low end torque though, if I had to guess I'd say both HO engines have the same or more torque at 2400 as the renix, it's just not the peak.

All I know about this is that when researching a cam swap, the machine shop's book said it was the same part number from 87- 01.

JJacobs said:

All I know about this is that when researching a cam swap, the machine shop's book said it was the same part number from 87- 01.

Click to expand...

That's definately wrong. An aftermarket cam would probably be the same part number throughout the years, since the only difference is the lobes.

There were definite camshaft changes - that was how they successfully deleted the EGR valve. I don't have the part numbers handy (I need to find my OEMR books) but the grinds are different, the profiles are different, and therefore the OEMR part numbers are different.

For aftermarket cams, they are the same all the way up - in fact, the same bumpsticks will work in the 258 and the 242, so there's a LOT of coverage to be had! The crankshaft mains are the same size as well, and there's a lot of other parts that are swappable as well.

5-90

martin said:

The AW4 transmission never was replace by a Chrysler transmission. I am told the AW4 is a copy of an old Ford transmission but with the problems fixed.

Click to expand...

I do believe that the AW4 is actually a Toyota transmission. When I have ordered parts for it, we always end up finding the AW4 listed with Toyota transmissions.