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renix system
- Thread starter njxj4x4
- Start date
cruiser54
NAXJA Forum User
- Location
- Prescott, Az
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
http://www.lunghd.com/On_Site_Tech.htm
This site has plenty to read on RENIX systems and later Jeeps too.
This site has plenty to read on RENIX systems and later Jeeps too.
The links provided by the others are great for debug which is critical with Renix but as some background:
The Renix system (Renix was a joint venture from Renault and Bendix) does everything you would expect from an engine control system and it performs very well. It was available on the Cherokee prior to 1991 but after the purchase of the Jeep brand by Chrysler, the new owner decided to use their own system.
In my opinion, the Renix ECU system is actually really good however, they key challenge with this system is that it has a non-standard mechanism for displaying trouble codes. Essentially, you need a very expensive (and becoming very rare) specialized diagnostic tool to read error codes which has resulted in forums like this that have figured out how to work around this. As you will see in the links below, there is a wealth of experience available to help with troubleshooting these systems but the good news is that when they are setup properly, they work really well.
A couple of things to be aware of on these models:
1) on Automatic transmission models the tranny has its own computer (TCU) that controls shift points
2) the basic functions of air/gas/timing are all handled by the ECU in the same way as other EFI systems so the basic rules are the same (crank sensors determine timing, O2 sensors modify fuel flow, throttle position sensors monitor gas pedal, MAF sensors monitor air flow.....
3) As you will see from the other posts, the biggest headache with Renix systems is that they are sensitive to electrical ground issues. Broken ground wires for the sensors (they all seem to connect to the engine block in the same place but they are small wires so they break) and the ground between the engine and the chassis can all cause headaches simply because they interfere with the computers ability to read the sensors.
4) while newer EFI systems can be reprogrammed to deliver more power or better fuel economy, the Renix (to the best of my knowledge) cannot be modified because the EEPROM that stores the operating parameters is sealed.
5) since Renix era computers are pretty basic, they didn't build a very good provision for the "check engine" light. Instead of using this light to help the owner detect if something is wrong, they simply built a fancy timer that automatically turns the light on after a certain number of hours of use (expecting the owner to take it to a shop for a thorough check and replacement of the timer). It is actually pretty useless but since the unit is easy to get to most people simply disconnect it.
As I said, the systems work pretty well but since the diagnostics are more of a shotgun approach, they tend to rely on tricks shared between owners. The check engine light function being (practically speaking) useless, the first signs that something is wrong typically come from seat of the pants (I've lost power or my gas mileage is poor or, I've gone through 2 catalytic converters in 1 year) or from the annual emissions tests that most cars in the US now have to succumb to.
HTH
Todd
The Renix system (Renix was a joint venture from Renault and Bendix) does everything you would expect from an engine control system and it performs very well. It was available on the Cherokee prior to 1991 but after the purchase of the Jeep brand by Chrysler, the new owner decided to use their own system.
In my opinion, the Renix ECU system is actually really good however, they key challenge with this system is that it has a non-standard mechanism for displaying trouble codes. Essentially, you need a very expensive (and becoming very rare) specialized diagnostic tool to read error codes which has resulted in forums like this that have figured out how to work around this. As you will see in the links below, there is a wealth of experience available to help with troubleshooting these systems but the good news is that when they are setup properly, they work really well.
A couple of things to be aware of on these models:
1) on Automatic transmission models the tranny has its own computer (TCU) that controls shift points
2) the basic functions of air/gas/timing are all handled by the ECU in the same way as other EFI systems so the basic rules are the same (crank sensors determine timing, O2 sensors modify fuel flow, throttle position sensors monitor gas pedal, MAF sensors monitor air flow.....
3) As you will see from the other posts, the biggest headache with Renix systems is that they are sensitive to electrical ground issues. Broken ground wires for the sensors (they all seem to connect to the engine block in the same place but they are small wires so they break) and the ground between the engine and the chassis can all cause headaches simply because they interfere with the computers ability to read the sensors.
4) while newer EFI systems can be reprogrammed to deliver more power or better fuel economy, the Renix (to the best of my knowledge) cannot be modified because the EEPROM that stores the operating parameters is sealed.
5) since Renix era computers are pretty basic, they didn't build a very good provision for the "check engine" light. Instead of using this light to help the owner detect if something is wrong, they simply built a fancy timer that automatically turns the light on after a certain number of hours of use (expecting the owner to take it to a shop for a thorough check and replacement of the timer). It is actually pretty useless but since the unit is easy to get to most people simply disconnect it.
As I said, the systems work pretty well but since the diagnostics are more of a shotgun approach, they tend to rely on tricks shared between owners. The check engine light function being (practically speaking) useless, the first signs that something is wrong typically come from seat of the pants (I've lost power or my gas mileage is poor or, I've gone through 2 catalytic converters in 1 year) or from the annual emissions tests that most cars in the US now have to succumb to.
HTH
Todd
