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The term Renix has a number of applications. In certain carburettor powered Renault and Volvo models, it provided an electronic ignition system, consisting of an ECU to replace the job of contact breaker points in the distributor. The system used an angle sensor and a number of fuel sensors to provide a maintenance free ignition system.

Later, the name was synonymous with a form of fuel injection. In such an application, it consisted of an Engine Control Unit (ECU - also known as Electronic Control Unit) and a number of sensors. It was first seen in engines produced by Renault (Renault 21, 25 and Espace) in 2.0 and 2.2 capacites, but is better known in America for its application in the AMC 4.0 L (displacing 3960 cc or 242 cubic inches) straight-6 engines that was developed by Renault and Bendix. Production began by American Motors (AMC) with the 1987 Jeep Cherokee (XJ) models. It was preceded by the AMC Computerized Engine Control, and followed by the Mopar MPI system.

Renault background and application

The Renix system was used in the J series engines as fitted to the Renault 21 and Savanna/Nevada, the Renault 25 and the Renault Espace. It was a multipoint fuel injection system, as opposed to a singlepoint system, with a number of air, throttle and pinking sensors, and an advanced computer. Application of the system could first be seen in 1984, 3 years before its American debut. The Renix system pushed the power of the carburettor fed 1995cc engine from 104 BHP to 120 BHP. It could also be found in 2.2 engines fitted to R21, 25 and Espace models.

Background in the AMC application

The Renix ECU has a powerful microprocessor that was advanced technology for its time. It also incorporates an engine knocking sensor that allows the computer to know if detonation is occurring, thus allowing the computer to make adaptive control by individual cylinder corrections to prevent pinging. The knock detection uses the signal from a wide bank accelerometer mounted on the cylinder head. Good signal to noise ratio is obtained primarily through angular discrimination.

The Renix computer was used through the 1990 model year. Unfortunately, the Renix system is now handicapped because there are few scan tools that can be "plugged in" to this on-board diagnostics computer.


  • 1986 - Renix TBI is first available on Jeep 2.5L motors and improves the drivability of the Cherokee plus it makes a very good impression in the Comanche pickups over the 2 months of carbureted versions. The power increase is quite noticeable. Changed to Renix MPFI in '89, then replaced with the Chrysler HO EFI in 08/90.
  • 1987 - the new Renix controlled 4.0 L engine was rated at 173 hp (129 kW) and 220 lb·ft (298 N·m)) of torque.
  • 1988 - output increased to 177 hp (132 kW) and 224 lb·ft (304 N·m) of torque, due to higher compression ratio.
  • 1991 - Chrysler Corporation (then the owners of the Jeep brand replaced the RENIX control system with their own OBD-I-compliant control electronics.

The RENIX control system was only found on the 1987-1990 Jeep Cherokee and Comanche with AMC-designed engines (the control setup used with the 2.8 L (≈171 cu in) V6 was OBD-I General Motors, and the early Diesel was a 2.1 L (≈128 cu in) Renault turbodiesel I4 that used its own specific control setup.) The CJ/YJ "Universal" Jeep Wrangler did not get the AMC 4.0 engine until 1991, when it was accompanied by Chrysler-designed electronics as well. Until then, it retained the AMC 258 cu in (4.2 L) engine with a carburetor. No other Jeep vehicle was equipped with RENIX electronic controls.

Inspection stations

Owners in California (and other "Smog Control" jurisdictions) should note that the RENIX control system is "pre-OBD," and therefore does not have a "Check Engine Lamp," nor does is "store" or "throw" Diagnostic Trouble Codes (DTCs) or "Parameter IDs" (PIDs) - see: OBD-II PIDs. This is a common issue when going through vehicle in an inspection. Most inspection stations are not aware and will try to explain that the CEL/MIL "doesn't work" (note: there may be a cutout for it, but no bulb). It is recommended to point out to the inspection technician the "OBD Exempt" federal emissions label (located under the hood) and/or have the factory service manual as a reference to avoid this problem.

Other RENIX applications

  • Volvo 700 series - B200K 2.0 L inline-4, naturally aspirated with Renix ignition.
  • Renault engines

See also

  • Boccadoro, V. and Kizer, T.; (1984). Adaptive spark control with knock detection, Society of Automotive Engineers, Inc., Warrendale, PA.
  • Mitchell International, Inc.; (1991). Mitchell's Electronic Fuel Injection Troubleshooting Guide: Domestic Vehicles, ISBN 1-55561-032-3. (chapter contents include AMC/Jeep; AMC; AMC/RENIX; AMC/RENIX II)