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91+ 4.0 into a Renix...?

anony91xj

NAXJA Forum User
Location
North Jersey
OK, well I have to drop a new motor in the Cherokee next week. I don't know if the engine I've got coming from the junkyard is going to be a Renix or a 91+, I just know that it's a used 4.0 engine.

First question, are there going to be any issues with sensors or wiring harness incompatability if they send me a 91+? I know they used Chryco's ECM, but I don't know if all the sensors, widgets, and wiring connectors were the same. Any way of telling by looking at it if it's a 84-90 or 91+?

Second question...the engine coming out is not a HO motor. I don't think it's that big a deal, but is there any way to tell by looking at it if they've sent me a HO or Low-Output motor?

Thanks.
 
I may be smoking crack or something, but if I remember right there was renix, and then in 91?? they upgraded to the HO motor.

and for some reason the main differences between the two sticks out in my mind as being a different head and computer.

Like I said, I'm just shooting in the dark on these but it should give you a lil direction to dig.

Good Luck
 
The Renix was replaced with the HO. The wireharness and ECU is different. You need the right wire harness for the right year motor.
 
You can tell what it is by the intake manifold, or the intake posrts on the head if it's a bare longblock.
You can use any block in any year, you just need the proper sensors for YOUR ECU. It would be really helpful if you told us what year XJ you're putting yhr motor into. THen we could tell you what you need to do.
 
OK, it's going into a 1987 XJ and the motor I just got this morning is definitely a 91+. My main concern is the ignition coil differences, that and anything else I need to know would be helpful before I attempt to tackle the job. The '87 still runs, so I guess I could just swap all the sensors and manifolds onto the new block? It would be easiest by far to use the 87 harness, ECU, etc...at least that's what I'd think. Thanks.
 
You can use your Renix wiring and electronics with a newer motor. You will need to retain your present distributor, flywheel or flex plate, and other electronics like O2 sensor TPS.
The main concerns with this swap are the Throttle body, EGR system and fuel lines. The throttle position sensor will need to be adapted.
Read this:
http://www.rockmodified.com/offroad/Tech/TB/tb_perf.htm
For the fuel lines, the Renix has them front and rear. The Renix fuel rail doesn't bolt up to the HO intake manifold. The injector spacing is the same. Either you could relocted the tabs for the bolts or adapt an HO fuel rail. If you live in a state that does smog checks, the you will probably have to adapt the EGR system.
Or as posted you could swap on your Renix Head. That would negate all the above problems.
Tom
 
75SV1 said:
You can use your Renix wiring and electronics with a newer motor. You will need to retain your present distributor, flywheel or flex plate, and other electronics like O2 sensor TPS.
The main concerns with this swap are the Throttle body, EGR system and fuel lines. The throttle position sensor will need to be adapted.
Read this:
http://www.rockmodified.com/offroad/Tech/TB/tb_perf.htm
For the fuel lines, the Renix has them front and rear. The Renix fuel rail doesn't bolt up to the HO intake manifold. The injector spacing is the same. Either you could relocted the tabs for the bolts or adapt an HO fuel rail. If you live in a state that does smog checks, the you will probably have to adapt the EGR system.
Or as posted you could swap on your Renix Head. That would negate all the above problems.
Tom
Thanks for the link, I think that'll be helpful. I don't plan on swapping the heads if it's not completely necessary because I'm lazy and that's a PITA. I can reroute or make some new fuel lines to make the HO rail work.

Retaining the old distributor is not a problem (I was planning on doing that anyway if possible, it's brand new), and I have a 5-speed while this engine came from an automatic, so I'm gonna have to swap the flywheel and install a new pilot bearing anyway.

I was thinking I'd just eliminate the EGR completely and plug the hole in the manifold, if it causes problems with emissions testing...well I'll cross that bridge when I get to it. Not too concerned about emissions tests honestly.

Will the Renix exhaust manifold work with the HO head at all? I think they exit at different angles, or am I wrong on that? Will the HO manifold mate up easily with the Renix downpipe? I work at an exhaust shop so fabricating some pipe is really no big deal, just trying to avoid as much extra work as possible.

Last remaining question...I'd have to use the old CPS as well, correct?

Thanks again for the info :)
 
Oh, one more thing about the TPS. I saw on another site where someone mentioned that the non-HO engine had a 2-wire TPS (one for ECM, the other for the TCM), while the HO TPS only had one wire for the PCM. Since mine is a 5-speed and doesn't need any signals for a TCM, do you think it'd be possible to just use the one-wire HO TPS?

I'll have to look up the specs tomorrow, and then take a look at both the old and new sensors to see if it'll actually work. Just a theory.

EDIT: This page
http://www.off-road.com/jeep/cherokee/99/09_sept/engswap/engswap.html
 
I can't comment on the wiring of the TPS. The Cherokee article covers a lot of points. If you look at their radiator conversion, they have a link to another site for adapting the coolant sensor.
As far as the exhaust, I'm using a Clifford header. Actually, I'm changing my wiring and ECM to '95.
Tom
 
What would I have to adapt for a coolant sensor? I'm going to be reusing the Renix closed cooling system. The only sensor on the engine that I'm aware of on the Renix setup is the one for the guage (actually it's not even a guage, just a light on mine) at the back of the head. And even that's not a concern because I have an aftermarket mechanical guage with a sensor in a 91+ housing on the Renix motor already.
 
I guess nothing. My swaps a bit different. Also, I haven't gotten to that point yet. I have the engine in. I'm swapping in an NV3550. I still have to do the tranny mount. Then its back to getting the accesories, radiator and wiring done.
Tom
 
anony91xj said:
What would I have to adapt for a coolant sensor? I'm going to be reusing the Renix closed cooling system. The only sensor on the engine that I'm aware of on the Renix setup is the one for the guage (actually it's not even a guage, just a light on mine) at the back of the head. And even that's not a concern because I have an aftermarket mechanical guage with a sensor in a 91+ housing on the Renix motor already.
ive got a 97 block and head in my renix 89MJ and the coolant sensor did have to be adapted. just put the 89 unit into an adaptor and run it up front where the hole is on your thermostat housing, you have to hve that sensor for closed/open loop with the renix systems I THINK
correct me if im wrong somewhere
-nick
 
Oizarod115 said:
ive got a 97 block and head in my renix 89MJ and the coolant sensor did have to be adapted. just put the 89 unit into an adaptor and run it up front where the hole is on your thermostat housing, you have to hve that sensor for closed/open loop with the renix systems I THINK
correct me if im wrong somewhere
-nick

I thought the Renix ECU temp sensor was in the radiator. The 84-90 4.0's didn't have a sensor in the Tstat housing. I haven't looked yet though, I'm not gonna start the swap until it looks like next week, I got the motor and everything, but no time.
 
hey i put a 92 ho motor in my 89 i used every thing off the 89 but the block even used the intake and exhust the idle is crazy idles under 500 most times i changed the 02 idle air controll map and cleaned the intake it just doesnt feel right you think i did sum thing wrong in the swap what am i missing thanks guys
 
Just use everything from the Renix, with the exception of the EGR system, and you will be fine.

The OBDI/OBDII (91+) eliminated the EGR system and my understanding is that the cam profile was altered to compensate for the EGR elimination. If you are running the EGR with an HO engine you may not be at optimal operation.

One thing that might need a little finesse is the knock-sensor. It changed a bit at one point and then was eliminated in later years.
 
Yes I've done this, the only part that requires thinking is the TPS adaptation. No you can't use the HO TPS at all, it works entirely differently and will not work on Renix electronics. Adapt it or buy the kit from Hesco. The fuel rail will work as long as it is the earlier HO one that still has a return line, if this is the case you just need to install the Renix injectors in it and adapt the fuel lines to connect to it. There is several temp sensors, the one for the fan is in the rad, so that is not a problem. Some earlier HOs had the sensor in the head, and I don't know if the Renix sensor fits in that hole, as I bastardized my gauge cluster to use the HO gauge. The other sensor is in the block, this is the ECU sensor, and I believe it is the one that I have in the HO thermostat housing, and the wiring appears to have reached. Knock sensor: you may or may not have to drill a hole for it, and you may have to find out the thread size and tap it. It won't run without it hooked up (although it will run with it plugged in and just sitting there). The exhaust manifold from Renix will line up with the (at least the 7120) head, however the ports may need to be made bigger(mine were made bigger, but I don't remember if this was nessesary or if i was just matching the gasket), and of course you would need to plug up the EGR hole. It is probably best to make the HO exhaust work on it unless you already have something aftermarket. Either way you need to use an HO gasket, as the Renix gasket will block the fuel injectors on the HO intake.

Don't forget to swap any sensors and it will work fine.
 
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