Switching From Renix to OBD11 ~ Considering ~

[Drahcir495]

3 hours ago, Gojira94 said:

 

And IIRC, the 96 MAP sensor is a one year only thing. Mounted on the throttle body, has same output as 87-95, just packaged differently, looks like the 97-01?

I should have came to you guys earlier. I won’t make that mistake again 

[ghetdjc320]

I think we’d all be interested to see how he does it. 96 was an interesting year for the XJ as it got an obd2 conversion but had to retain much of the obd1 system including gauges. 97 was much more of an update and went to the canbus system. When converting to obd2, there is an adapter that was made for the stock obd1 harness (not renix) that works with the 96 ecu (pictured below). The renix flywheel tone ring is not compatible with obd1/2 though. Gather some of the specifics on what exactly will be done in the swap. If he goes 97+ than a cluster swap may be in order for at least the tach signal. 
 

 

[Drahcir495]

I will keep you updated as much, as my son says “smooth brain” can grasp. I will make a list and discuss with him these questions. 
 

Tone ring? Is that the teeth on my manuals fly wheel? 
 

The wiring harness that came out of the xj is also being used.

 

will my gauge cluster work with the system?

[Gojira94]

 

21 hours ago, Drahcir495 said:

Tone ring? Is that the teeth on my manuals fly wheel?

 

"Tone ring" -yes, the number and spacing of the voids in the crank sensor signal. Represent cylinder timing for fuel/ spark events (3 vs 12). Renix flywheel on the left, HO on the right:

 

 

Flexplate for autos has the same tooth arrangement for Renix vs HO.

[Drahcir495]

Thank you Gojilra94. Damn I hope he knows this stuff. Again, I will make up a list of questions for him in the morning. I will get with him next week about the list. Will keep you all posted on this journey. I do wish I had asked earlier. Hopefully it all works out in the end

[gogmorgo]

Just my two cents, cause I haven't thrown them in yet. I'm betting the only reason your mechanic wants to convert to OBD2 is because he can't plug his diagnostic tool into an OBD2 port on your truck. To me that's not a valid enough reason to justify a conversion.
Now I haven't looked into every possible diagnostic tool out there, but last time I dug into it every diagnostic (scan) tool that I had at hand had the software to communicate with the early ECU, it was just a hardware issue of having the correct adapters to plug into it. And the correct adapters could be had, you just had to buy a very expensive kit of OBD1 connectors for darn near everything pre-OBD2 instead of getting them individually by application. But if you're paying someone else to do the work, I'd be willing to bet you'd get more value out of your dollars buying the mechanic the tools to talk to your truck instead of paying them to replace a bunch of parts that don't need fixing.
Or you could go on eBay and buy a pro-grade diagnostic tool from the '90's or early 2000's that comes with the adapters you need for less than the new set of adapters, which is what I did. The early diagnostic bricks are kinda clunky by modern standards but they do work.
Probably too late now for this truck but for anyone else stumbling across this thinking about going the same route.

[ghetdjc320]

Aside from the reasons for why your mechanic wants to do this, I am also quite curious about how he will accomplish it and if he is aware of the rather large changes required aside from an ecu and harness swap. It’s one thing when you have a donor XJ sitting around to swap everything over from. Quite another to take a running renix and convert it while retaining renix era parts. 

[Drahcir495]

22 hours ago, ghetdjc320 said:

Aside from the reasons for why your mechanic wants to do this, I am also quite curious about how he will accomplish it and if he is aware of the rather large changes required aside from an ecu and harness swap. It’s one thing when you have a donor XJ sitting around to swap everything over from. Quite another to take a running renix and convert it while retaining renix era parts. 

Definitely too late. I have an 98 XJ motor already in it. I used the Renix flywheel and fuel rail. Then one did of accessories is HO and the other is Renix. I also have an adapter to control the carb using the Renix TPS. The donor XJ is there, so it’s all coming out of it. 

[ghetdjc320]

1 hour ago, Drahcir495 said:

Definitely too late. I have an 98 XJ motor already in it. I used the Renix flywheel and fuel rail. Then one did of accessories is HO and the other is Renix. I also have an adapter to control the carb using the Renix TPS. The donor XJ is there, so it’s all coming out of it. 

Also will need to run the higher pressure fuel pressure for obd2. The regulator is in the tank for 97+ XJ/TJ’s. It’s a return less style system. Psi requirements are somewhere in the 50’s iirc. On an MJ, you can use an external adjustable style regulator

[75sv1]

Not sure on having to change the Fuel system. Boostwerks does have a kit to adapt a return system to a late style 4.0L. I am confused about the choice of a flywheel. RENIX flywheel if converting to a HO or Late HO. ?? Or just swapping in a 97 4.0L and keeping the RENIX? 

[Gojira94]

On 9/16/2024 at 7:24 AM, 75sv1 said:

I am confused about the choice of a flywheel. RENIX flywheel if converting to a HO or Late HO. ?? Or just swapping in a 97 4.0L and keeping the RENIX? 

 

If Renix computer 87-90, and all associated sensors it needs/ understands - Renix flywheel to make the proper signal with the crank sensor. Plus Renix harnesses.

If HO era computer 91-01 (all flavors), and all associated sensors it needs/ understands - HO flywheel to make the proper signal with the crank sensor. Plus HO harnesses.

 

To run a complete 91-01 HO setup in an 87-90 MJ/XJ:

HO flywheel, change out all the sensors to the ones HO computer needs/ understands, HO computer/ harnesses for the matching year(s), including VSS setup/ instrument cluster/ cruise control system, if applicable. EDIT: Also need to make fuel system delivery changes as noted above by ghetdjc320.

 

To run that 97 HO 4.0 on Renix:

Renix flywheel, change out all the sensors to the ones Renix needs/ understands, Renix computer, Renix harnesses (preferably 89-90 to avoid C101 headaches), including VSS setup/ instrument cluster/ cruise control system, if applicable.

 

I've got a 93 YJ drivetrain that I'll be running on Renix in my 87 MJ project. I've acquired the Renix flywheel and all the sensors Renix computer needs/ understands. Also got the Boosted Technologies version of the TPS adapter, so I'm free to run whatever throttle body/ intake combo I want. My rig came to me with a complete and intact set of 89-90 4.0 Renix harnesses and computer, so that drove my decisions on doing Renix control of an otherwise mechanically HO engine. Using the cable driven speedo and Renix era cruise control.

[scguy]

There's benefits to OBD1 vs Renix but then Renix has a few benefits over the OBD1 setup. 

 

I am running 94 harness and ECM on my MJ. I like the wiring better, it starts faster, but a REM would be really cool. I can always get the adapter and go OBD2 with the ECM if I want.