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More power for your 87 and 88 Renix 4.0

cruiser54

NAXJA Forum User
Location
Prescott, Az
Confirmed over the weekend the difference in ECUs used on Renix 4.0s.

I was sure there was a difference but I used my neighbor as a guinea pig with his 87. I let him use one of my 89 to 90 ECUs as long as he installed it.

He came back from the test drive smiling from ear to ear.

Last night he installed the later model Renix TCU, I'll have a report back in a day or so.
 
Glad to hear this news.. I have an 88 that compared to my 91 just seems sluggish in the power department.. I recently bought a parts 1990 and took the ECU out and based on this wright up I will definitely be installing it in my 88 this weekend. Be sure to post back on any differences with the TCU, I also have that out of the 1990 that I will swap in if it makes a difference.
 
What is a source for the ECU? JY Only? Thanks Cruiser!

That's one place I've gotten them. I've also parted out an 89 and a 90 XJ and scored them that way.

If and/or when you guys do this, you're obligated to report back.

I've done it more than a few times. I forgot what difference it made until I got my friend across the street to swap a 90 ECU from my parts Jeep into his 87.

Didn't tell him to expect much, just that it was newer. I really played it down. He was tickled.
 
When I saw this post was started by Cruiser54, that's all it took: this man and his posts has helped me so much getting my Jeep to run like a scalded cat. How much better can it get?

I found a 1990 ecu on ebay and got it for $50 shipped from Kansas. I recall that 5-90 said he had only seen one failed Renix ecu, so that was another reason to try this.

I will give a report once I get it installed. Keep those tips coming Cruiser. You might want to add this to your other Renix tips!
 
When I saw this post was started by Cruiser54, that's all it took: this man and his posts has helped me so much getting my Jeep to run like a scalded cat. How much better can it get?

I found a 1990 ecu on ebay and got it for $50 shipped from Kansas. I recall that 5-90 said he had only seen one failed Renix ecu, so that was another reason to try this.

I will give a report once I get it installed. Keep those tips coming Cruiser. You might want to add this to your other Renix tips!

I guess it could be #28 and 29? ECU and TCU?

I know for sure about the ECU, and the TCU from 87 to 88. Not sure on TCU from 88 to 90.

Looking forward to your report.

Have you eliminated your C101 yet?
 
Around here(San Diego), 89 & 90 renix xjs are scattered through every junkyard. The '90 computer I grabbed cost me $20.
I intend to pick up at least one more-just because.
Oddly, the one I got a couple months ago does not have the typical 89/90 part numbers that are quoted everywhere. The one I grabbed is an original jeep ecu with part # 56006078. It was out of a 4.0/aw4/4x4 with a very late 90 production date....somewhere around august of '90, iirc.
 
Around here(San Diego), 89 & 90 renix xjs are scattered through every junkyard. The '90 computer I grabbed cost me $20.
I intend to pick up at least one more-just because.
Oddly, the one I got a couple months ago does not have the typical 89/90 part numbers that are quoted everywhere. The one I grabbed is an original jeep ecu with part # 56006078. It was out of a 4.0/aw4/4x4 with a very late 90 production date....somewhere around august of '90, iirc.

IF you can, pick me up one when you get a chance. This will help when I do the swap from my donor XJ to my MJ.
 
Around here(San Diego), 89 & 90 renix xjs are scattered through every junkyard. The '90 computer I grabbed cost me $20.
I intend to pick up at least one more-just because.
Oddly, the one I got a couple months ago does not have the typical 89/90 part numbers that are quoted everywhere. The one I grabbed is an original jeep ecu with part # 56006078. It was out of a 4.0/aw4/4x4 with a very late 90 production date....somewhere around august of '90, iirc.

There is also a production date on the ECU for confirmation.
 
Cody reported back last evening on changing his TCU from the standard 87 model to an 89 model I had from a parts Jeep.

Better shift points with less lugging and definitely noticeable.

I knew they changed the TCU after 87 due to customer complaints, and 88 and later seem to work great. My wife's 88 shifts like my 90.
 
Cody reported back last evening on changing his TCU from the standard 87 model to an 89 model I had from a parts Jeep.

Better shift points with less lugging and definitely noticeable.

I knew they changed the TCU after 87 due to customer complaints, and 88 and later seem to work great. My wife's 88 shifts like my 90.

Great. Something else to buy:)
 
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