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.

 

Kinda late reporting back. Later model tCU yields even more performance gains. No loss of MPGs.

 

Wasn't the original difference in horsepower only about 7-9 greater for the 89-90 over the 87?

 

173 in 87. 177 in 88, 182 in 89 and 90.

 

Well that's a 9.5% power gain.

Is it plug and play?

 

Absolutely. But only if you call removing and reinstalling an ECU from a Renix Jeep playing!!

Here's a photo of the mounting NUTS holding the mounting plate to the underdash..

 

So we are discussing later AMC, not MoPar ECUs?

 

89 to 90 ECUs and 88 to 90 TCUs. Those are desirable.

 

Couldn't I just fart down the intake for some extra MPG's?

 

Possibly. But you would want to preface that with a week long steady diet of cauliflower, broccoli and sauerkraut.

 

That's too complicated.

Refried beans will do just fine, and quicker.