Hot rodding a RENIX in Cali

Alex E

Alex E

NAXJA Forum User
Location
Bay Area, California
Hey guys, I've got to pull the engine on the Jeep. Its a 87, manual tranny with a lovely knocking 4.0. Seeing how I have no choice but to fix it I've decided to try and open up the power band a little bit. I have ALL RENIX parts on it and all smog equipment but the bottom end and cylinder head are a 95 HO engine, I live in Cali and I need it to pass smog. Whos done what and what works on these engines? Right now its got the 95 cam shaft but when I get it rebuilt I was thinking of purchasing a very mild cam or maybe installing a new RENIX profile cam. I found a place to get new injectors and a bored T-Body also. Anyone do roller rockers? I would like to keep it reliable and smogable. I just need some ideas, input or other advice on what works and what doesn't do much. Not sure where this thread will end up but hopefully I get some ideas flowing!:eyes:
 
The injectors, if they're the four disc type, will help along with the bored TB. I have a Renix with this setup and an HO in a Renix XJ, like yours, with the same setup.

Is your Jeep lifted at all? If so, you can have a muffler shop replace your "crushed" exhaust downpipe with one that isn't. Worth it.

If you can grab an ECU out of a 90 Renix from a JY, you'll pick up a little bit, too. The 87 ECU supercedes to the 90 FWIW. Little snappier, doesn't seem to lag after a shift like the original ECUs were programmed to do.
 
The TCU is seperate, so I beleive REnix ECU is Renix ECU.. EGR should still work.
He said JY..not YJ, JY = Junkyard
I have my XJ registered at my uncle's house in a county where only upon change of ownership is smog required (=
 
Ha, good call. I was like whats it matter if it was an XJ or YJ. JY works though, I dunno must have been before my morning coffee. So 90 PCM is really better huh? I think I'll go grab one and try it. Does anyone know what management or strategies were changed in the PCM? Obviously this is plug n play right? They didnt change any connectors or wiring stuff?
 
As for the engine management and the fact my Jeep has EGR I should probably run a RENIX cam right? I would think its a better match then the HO cam in there. Anyone know of a decent really mild RENIX ECU compatable cam?
 
Cool, I'll try one out. I never understood why my Jeep always feels so bogged out compared to others I've driven. Hopefully the idle strategy is better too. My IAC never seems to know what to do. I've changed almost every sensor on that car and have performed all TSB's from Chrysler and its still quirky.
 
When installing the new ECU, use a pick to tighten the connectors in the harness. Also spray it and the ECU pins with a good quality electronics cleaner before reassembly.
 
Good idea, I was thinking maybe I'll test the power and ground circuits for voltage drops. Who knows what other bad conncetions there are. Even though my Jeep is rust free and dry because California weather and
 
Good idea, I was thinking maybe I'll test the power and ground circuits for voltage drops. Who knows what other bad conncetions there are. Even though my Jeep is rust free and dry because California weather and its in decent shape my two biggest worries are the fuse box and all the connectors on the fire wall. It just looks like a nighmare for electrical gremlins.
 
Alex E said:
Good idea, I was thinking maybe I'll test the power and ground circuits for voltage drops. Who knows what other bad conncetions there are. Even though my Jeep is rust free and dry because California weather and
Click to expand...


Ive been meaning to do the same on my 89....
And This is the first ive heard of a 90 computer being "more agressive"
Is it enough to notice in the but dyno???
 
I got these battery terminals that you heat with a torch and dunk the cables in for a good connection. So I used 2 gauge fine braid copper welding wire and re did all my grounds and power to the starter. I added an extra ground from the block to chassis along with block to battery. I havent changed cylinder head to fire wall though, its looks good and I've cleaned it and the only other ground I've found was the one up by the head light for the wiring harness. That looked good, clean and tight so I left it alone.
 
Alex E-Scrape the paint from under the firewall ground and reattach it. The other things you did are great. Be sure to remove, scrape, clean, polish and shine the connections at the engine dipstick tube stud. Very important.

outlander-Butt dyno proven but keep in mind the ECUs evolved. So, a 90 ECU into an 87 will be more noticeable than a 90 ECU into an 88 or 89.
 
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Thats what sucks about my Jeep, its a total learning experience for Jeep. I have a 87, first year of RENIX. In all honesty my Jeep has been pretty reliable though Im just particular about up keep and what not so when things dont work right then I have to fix them. No matter how small the issue is.
 
Alex E said:
Thats what sucks about my Jeep, its a total learning experience for Jeep. I have a 87, first year of RENIX. In all honesty my Jeep has been pretty reliable though Im just particular about up keep and what not so when things dont work right then I have to fix them. No matter how small the issue is.
Click to expand...

You should clean out your C101 connector if you have an 87...............
 
c101 is the big plug mounted on your firewall right above the brake booster that all your
engine electricals go to, then route from there to your computer under the dash. You can literally pull it in half and clean all the electrical connections. Mine was filthy the first time i pulled it apart.
 
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