Renix dead swap H.O. need info...

Here is the low down, I have a 1990 xj stock.

the renix engine has a rod knock, and recently has died on me while on the trail, just got it home, I have NO injector pulse, I don't think its the sync sensor, and ive heard the ECU's are not likely to go bad, im guessing that it is in the harness somewhere, I don't want to fuss with going through entire harness and looking for something that might not even be there.

I can get either a 95 motor, complete harness, and computers for 300
or
a 96 motor, trans, transfer case, and every electric on harness for 500

I know that i can swap it in with the harness, and on the 95 i would need to make my tps work with the throttle body so my trans shifts. and i would have to get new linkage and accelerator cable. (for this engine i am wondering if i can just use the renix throttle body and make an adapter plate for the manifold, does anybody know if this will work and will the renix tps work for the HO ecu?)

or with the 96 i would need to find a instrument cluster so my speedo works right, because the 96 uses a VSS, and the renix uses a speedo gear.

Please if anybody has any input at all id appreciate it, or if anybody has ever done this swap can give me info on it

Buy the 1995 for $300, put just the engine in with the original Renix setup, sell the rest of the harness and computers, etc.

I do not want to use anything off of the Renix. It has done nothing but give me problems and 12mpg, I don't want the cooling system or the sensors, the only thing i plan on using is the TPS to control my transmission

change your rod bearings for 30 dollars, that should fix your knock/ piston slap. Then check your ground strap from the cylinder head to the fire wall. Its probably ready to crumble to dust by now.

the renix aint dead it just needs some love. Just because you think throwing some newer junk under the hood will be some miracle fix does not make you right. You dont know the history of those engines either.

Ok, check this thread:

http://www.naxja.org/forum/showthread.php?t=983632&highlight=engine+swap

This guy has done what you are contemplating. PM him and see what is involved.

Good luck, let us know what happens.

I do know the history of these engines, I have already replaced all the grounds, been in the harness before, and replaces the CPS, TPS, IAC and coil, I just don't want to mess with the motor anymore, and i would have to pull engine or drop front axle to replace rod bearings, got half way there only to not be able to get the pan down,

and seriously where do you get off telling me what i know. ive spent many hours reading and working on these motors, this isn't my first one

I have found that the RENIX setup is able to tolerate some downright brutal abuse - and your getting 12mpg is indicative of a problem (replace the HEGO recently? That's usually good for a few MPG...)

For the FI issue, concur with checking/servicing/replacing the primary chassis ground at the cylinder head-firewall junction. Also suggest adding a secondary ground (10AWG or larger) from the battery negative post directly to the chassis. Both contact points with the chassis should be stripped down to bare metal and a corrosion inhibitor applied (something like Gardner-Bender Ox-Gard - you should be able to find that in your local hardware store's electrical section. No "liquid electrical tape," and no WD-40!)

The MAP is also probably due for replacing, and the IAT tends to get crapped up with carbon from the EGR circuit. Both of these are standard GM parts of the vintage, and should be fairly cheap.

TPS action should be checked for skips or flat spots using an analog (sweep needle) ohmmeter, I've described how to do this elsewhere. I really should post a video sometime...

The rod knock can be solved by replacing the crankshaft bearings - but I would suggest dropping the sump and miking the journals before securing replacements. Yes, the OEM nominal size should work - but there are undersized crankpins from the factory (for various reasons,) and while they should be stamped as a code on the side of the block, that doesn't always happen. "Measure Twice, Cut Once."

Given proper maintenance - just like anything else more complex than the average rock - there's nothing wrong with the RENIX setup. In fact, I prefer it to the OBD-I (1991-1995) setup, and the OBD-II is on a par with it (I'm too used to doing my own thinking to really like OBD. I'm just cranky...)

To get the pan out on a stocker, you should be able to get enough room if you jack the front end up far enough to let the axle droop fully. If that doesn't give you enough room (it usually has for me, but doesn't always,) take your stock bottle jack out from under the back seat and wedge it in between the axle tube and the frame rail, and get the extra half-inch to inch you need that way. Last resort - you may find it necessary to unbolt one end of the front track bar, but I've never had to (I've had five RENIX rigs, and I've done a block-in-place re-crank and overhaul, two rear main seals, and one oil sump gasket that didn't come with any other work.) All of these were done without having to tear into the front suspension - and the only one that was lifted was the 87 that I did the re-crank on (and I managed to do that one with all four feet on the ground. That 3" lift gave me plenty of room.)

You will have to finagle just a bit to get past the oil pickup, but its doable.

You may also find it useful to unbolt the transmission mount from the crossmember, and use a bottle jack or a floor jack to lift the tailend of the transmission and transfer case - that also gives you some room up front (and what well-organised garage doesn't have several jacks lying about? I have two floor jacks and three bottle jacks - all of which have been bloody useful!)

And do play nice with others - unless you explain your qualifications and history beforehand, no-one is going to know - and it's often safest to assume that you need as much help as possible. That's usually not being insulting, it's just honestly trying to help. It takes a while before one becomes recognised as a "guru" on any subject...

Im sorry about snapping at him, the knock has been there for a while, the guy who i bought it from actually tried to hide it from me when i bought it. i assume that there is damage to the crankshaft from being loose so long, when i told him about him about the knock he said it was piston slap, but it happens at start up and midrange rpm, and when letting off the gas, its quite annoying. I like being able to check all sensors with a multimeter

Ive been talking to the guy with the 96 setup, he has all the linkage and driveshafts for that, and is willing to deliver it 50 miles to my house for free. I think im going to go with that.

my transfer case has been getting more and more difficult to shift in to 4wd with, probably something to do with the vacuum deal.

I'd just rather get the newer engine with less miles anyway.

bspoonman1993 said:

Im sorry about snapping at him, the knock has been there for a while, the guy who i bought it from actually tried to hide it from me when i bought it. i assume that there is damage to the crankshaft from being loose so long, when i told him about him about the knock he said it was piston slap, but it happens at start up and midrange rpm, and when letting off the gas, its quite annoying. I like being able to check all sensors with a multimeter

Ive been talking to the guy with the 96 setup, he has all the linkage and driveshafts for that, and is willing to deliver it 50 miles to my house for free. I think im going to go with that.

my transfer case has been getting more and more difficult to shift in to 4wd with, probably something to do with the vacuum deal.

I'd just rather get the newer engine with less miles anyway.

Click to expand...

It's up to you - but swapping full control systems can be a fair amount of work.

However, if you do end up doing that, I'd like to talk to you about getting the old control setup for a couple of projects I'm working on...

I vote for the 95 engine as its cheaper, and the cluster would be simpler to deal with.

The TPS signal that goes to the ECU is the same for the Renix and OBDI. On Renix engines the signal for the trans computer ran the opposite direction (o-5 versus 5-0), hence the need for the dual output TPS sensor.

You can either jerry-rig something so you keep the dual output sensor, or swap in a trans computer from an OBDI setup. If you look at the wiring schematic for the OBDI you'll notice the single TPS signal gets routed to both computers. As a tip, when looking at the trans computers: a grey connector is Renix and Green would be OBDI. Avoid red as those were for the ZJ chrysler trannies. You have to shave the keying ridge off the wiring harness connector to get it to plug in.

I have a 1991 trans computer (OBDI green connector) sitting on the shelf if you want it. $25 shipped.

Update... Im going to but a renix engine and tranny for 100!!!!, just got to do swap now

bspoonman1993 said:

Update... Im going to but a renix engine and tranny for 100!!!!, just got to do swap now

Click to expand...

nice, you have come to your senses! I put a reni with 291k on the clock from an '88 in my '90 and it runs like a top - just bought an 89 4.0 aw4 242 last week with only 166k on it - plan on keeping that a LONG time since its pretty nice (well, very ugly but runs SO nice)

this link may answer soem questions for others browsing the thread about putting a HO into a renix electrical system. http://www.terrainstompers.com/forum/viewtopic.php?t=14
(sorry about the spam at the top)

for the record I did not mean "you dont know the history of those motors" as in you don't know diddly about jeeps.

I meant that you really don't know what kind of life whatever replacement engine you buy has seen. That was part of my newer may not really be better argument.

Anyways good luck with your truck and I hope the renix to renix swap gives you good results.

5-90 said:

It's up to you - but swapping full control systems can be a fair amount of work.

However, if you do end up doing that, I'd like to talk to you about getting the old control setup for a couple of projects I'm working on...

Click to expand...

tru dat!

sorry had to say that...

I have encountered FAR to many problems to make my MPI swap (I had the 2.5 TBI) a practical solution. Stick to the renix, it's a much more flexible setup, and like 5-90 said, can be beat to hell and still run (even barely), while ONE problem with the OBDI system will shut it down for good. My RENIX TBI was running without two correct sensor inputs, getting about 12mpg in the 2.5 mind you, but still running nonetheless. If there was a RENIX MPI for the 2.5, I'd shoot for that in an instant over my OBDI MPI.

On another note, if you DO decide to swap everything up to 95, I have just about ALL the information you need, due to me being paranoid about thoroughness.