artur1808

Hey guys, I just have a quick question. I have been reading through the threads here and a lot of people are mentioning the Renix system. I was just wondering:

What is Renix?

I understand that it was only in the older XJ's, and that its frowned upon by most. But that's about all I know so far. So if you guys could help me out that would be great. Thanks

whowey

Renix is the name for the fuel injection/engine control system used on the 87-90 Cherokees.

People that frown on it don't understand it. It only uses a few sensors to make it run correctly. It is EXTREMELY durable. With a multimeter and a bit of brain you can diagnose your problems. Not to mention the fun when people at the box automotive stores try and hook their 'scanners' up to it...

5-90

RENIX is the control system used 1987-1990 (probably 1984-1986) with the AMC gasoline engines - the 150ci/2.46L I4 and 242ci/4.0L I6. The 1984-1986 GM V6 used GM OBD-I controls, and I'm not sure what the Renault turboDiesel used.

RENIX was spec'd by the partnership between AMC and Renault, and built by Bendix/King (the avionics people.) RENault + bendIX = RENIX.

RENIX is "pre-OBD," does not "store" or "throw" codes, and does not make use f the CEL/MIL like OBD. (I go roundy-rounds with the smog people on this on a regular basis - I take my 1990 FSM with me when I take my truck in.) Most of the sensors - save the TPS and HEGO sensors - are standard GM goodies, making them easy to find and to troubleshoot.

Just about all of the troubleshooting you need to be able to do - save about two tests that you don't need to do very often - can be done using a DMM (Digital MultiMeter.) The odd two tests require an analogue multimeter - digitals don't respond fast enough.

RENIX has been tougher than the hinges of Hell, in my experience, and my preferred control systems are RENIX/OBD-II/OBD-I (OBD-I suffers from being spec'd by CARB, while the OBD-II spec was taken over and standardised by SAE. That's why OBD-II makes more sense than OBD-I.)

The only thing in the RENIX system that I would consider an "inherent flaw" would be that the chassis is grounded by way of the engine block, using an open-braid ground strap. Replacing this ground strap and adding a direct ground from the chassis to the battery solves a multitude of issues you probably didn't realise you had - use min. 8AWG if you still have OEM wiring. If you order a wiring kit (like one of mine?) you can get the ground made in the same wire size as the rest of the kit - grounds should always be the same size or one larger than the power leads.

RENIX can be difficult to work with at first, but there are a few of us on various XJ/Jeep boards who can be considered "gurus" of the system, and we'll try to help you.

You may also want to go to Pirates of the Rubicon and download the RENIX FI manual from their tech archives, or I believe someone upped it to my RENIXPower group (a little brain trust I started to get some RENIX-specific issues seen to) at groups.yahoo.com/group/RENIXPower. Both places would have it as a .pdf file.