Late model 4.0L in a Renix MJ

[jamespwsullivan]

So my brother @kentsu66 and I can see the light at the end of the tunnel on our “Restore to Reasonable Daily Driver” project with my 1987 longbed.  There are still a couple of running issues that we are trying to track down.  For just a bit of context, the 4.0L in the MJ is from a 2003 TJ but I’m still running Renix.

Does anyone have any direct experience with adapting this later model 4.0 to a Comanche or Cherokee running the Renix MPFI?

What issues did you have? What worked well and what didn't.

[Ωhm]

03TJ(SBEC) and 87MJ(RENIX) used different trigger wheels for the CPS.

[jamespwsullivan]

are you referring to the flexplate?  we've been down that road.

[Ωhm]

5 hours ago, jamespwsullivan said:

are you referring to the flexplate?  we've been down that road.

 

Yes, talking about the flexplate. Sounds like you got this covered already.

[neohic]

There was a change in TJ and WJ 4.0s in ‘99… I think? Exterior wise, the engine mount locations changed. Few other threaded bosses changed too. I’d mock up everything on a stand before dropping it in the truck. 

[jamespwsullivan]

@neohicyes I wish I had been involved when the engine was being swapped!

 

[jamespwsullivan]

21 hours ago, Ωhm said:

 

Yes, talking about the flexplate. Sounds like you got this covered already.

Yes I'm pretty confident we do. I'm not sure it would even run with an 87 flex plate. But you bring up a good point. I don't have my parts books handy (out of town) but I wonder if the CPS is the same? 

[Ωhm]

1 hour ago, jamespwsullivan said:

I'm not sure it would even run with an 87 flex plate.

 

But the engine does run? If yes, CPS should be good.

[jamespwsullivan]

16 hours ago, Ωhm said:

 

But the engine does run? If yes, CPS should be good.

The engine runs and is pretty good most of the time except the conditions I stated in the original post. 

Someone on the Jeep Renix FB group mentioned something that made me think about what might be different about this setup I have.  For instance, do I have the best option (only option?) for intake manifold?  I have the block number which confirms the 2003 block and the head is definitely the 0331.  What differences might there be for the intake manifolds?  Some folks say that the later model intake will bolt up with some modifications but since there is no evidence that my throttle body is unmodified that makes me think that my intake is from the original Renix motor.  Could that make any difference?

[75sv1]

I started doing this swap. The motor mounts are one of the motor mount plates on each side. One is in about .900, the other out the same. I put on a '95 head and a 99+ intake. Also, mine is a manual trans. I was or am going to rewire to. Might check Cruise54 tips. He did a few RENIX to HO swaps. Its mainly the TPS that needs rewired. I was looking at keeping the WJ serpentine belt setup, with electrical fans. The '95 head does not have the one idler pulley threads on it. I might have found some setup that would work. Yet, I built a stroker from a 2000 block. Thinking of a FAST engine controller steup.