cruiser54 Posted April 9, 2014 Share Posted April 9, 2014 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. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted April 9, 2014 Share Posted April 9, 2014 So what you're saying is that I can use a ECU from an '89-'90 in my '88 and it should give a little better power? Same for an '89-'90 model TCM? Link to comment Share on other sites More sharing options...
cruiser54 Posted April 9, 2014 Author Share Posted April 9, 2014 ECU, yes. Here's the caveat. You can use one from an auto trans equipped XJ or Mj in either an auto or manual trans vehicle. If you use a manual trans ECU, you could have idle issues in gear with your automatic. 8953005428 is auto. 8953005429 is manual. There are other part numbers that will work and there is a "year date" somewhere on the ECU. TCU is more for just the 87s which had a different shift program than later years. Link to comment Share on other sites More sharing options...
Eagle Posted April 9, 2014 Share Posted April 9, 2014 I don't think an '89 ECU will make a difference in an '88 vehicle. The bump in horsepower and torque was from the '87 model year to the '88 model year. The original 1987 model was rated at 173 horsepower at 4,750 RPM and 220 foot-pounds of torque at 2,000 RPM. The horsepower rating for this version was raised to 177 horsepower at 4,750 RPM and 224 foot-pounds of torque at 2,400 RPM for model years 1988 through 1990. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted April 9, 2014 Share Posted April 9, 2014 Alright, well let us all know what happens. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 9, 2014 Author Share Posted April 9, 2014 I know what happens with the ECU for sure. 89 and 90 were 182 horsepower. 91 with HO was 190 horsepower. That's a whole different animal though. I swapped an 89 ECU into my wife's 88 a few years back and the difference is quite noticeable. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted April 9, 2014 Share Posted April 9, 2014 Do you have any for sale before I go to a jy? Mine is an 88 built in may so it probably has the less hp computer right ? Thanks Cruiser Link to comment Share on other sites More sharing options...
cruiser54 Posted April 9, 2014 Author Share Posted April 9, 2014 I've only got one for a manual trans. Not at the same time as swapping the ECU, in the interest of science, but sometime eliminate your c101 per my post 27 in my link below. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted April 9, 2014 Share Posted April 9, 2014 I'm going to eliminate my C101 and perhaps to the ECM swap. I want to squeeze as much power out of the HO stroker as I can get. Link to comment Share on other sites More sharing options...
jeephack Posted April 9, 2014 Share Posted April 9, 2014 I have an '87 MJ, 4.0 5 speed. I also have a '90 parts XJ, 4.0 auto sitting in the weeds. If I swap the XJ ECU into the MJ, I could possibly get a little better performance? Great!!! Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted April 9, 2014 Share Posted April 9, 2014 Cruiser I've cleaned every connector under the sun when I put the truck together from scratch and it runs well but i would like the + 8hp and mine is an auto . Do I need to eliminate the c101 to put the newer ecu ? Link to comment Share on other sites More sharing options...
cruiser54 Posted April 9, 2014 Author Share Posted April 9, 2014 I have an '87 MJ, 4.0 5 speed. I also have a '90 parts XJ, 4.0 auto sitting in the weeds. If I swap the XJ ECU into the MJ, I could possibly get a little better performance? Great!!! Yup. Do it. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 9, 2014 Author Share Posted April 9, 2014 Cruiser I've cleaned every connector under the sun when I put the truck together from scratch and it runs well but i would like the + 8hp and mine is an auto . Do I need to eliminate the c101 to put the newer ecu ? Sorry for the confusion. No, you don't NEED to eliminate the C101 in order to use the ECU. It's just a strong suggestion as a matter of course. What I would like to see, and I think you guys would appreciate, is eliminating the c101 in the meantime. Report back on that. Then, hunt down an ECU and install it. Make a comparison. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted April 10, 2014 Share Posted April 10, 2014 I will be doing that asap Cruiser thanks for the vast knowledge and knowhow . Link to comment Share on other sites More sharing options...
cruiser54 Posted April 10, 2014 Author Share Posted April 10, 2014 I will be doing that asap Cruiser thanks for the vast knowledge and knowhow . Looking forward to your report back. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted April 10, 2014 Share Posted April 10, 2014 I did a quick check and found a new 8953005025 it's listed for an 89 xj/ mj but the listing says it's an 8953005428 is it superseded ? Or just an earlier computer ? Link to comment Share on other sites More sharing options...
cruiser54 Posted April 10, 2014 Author Share Posted April 10, 2014 I'm a bit leary of that. The 428 was the superceded one. I would want one that IS a 428 for sure. Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 10, 2014 Share Posted April 10, 2014 I know what happens with the ECU for sure. 89 and 90 were 182 horsepower. 91 with HO was 190 horsepower. That's a whole different animal though. The never ending Renix owners' quest and the $$ people pump into it to just equal a stock non-aspirated basic HO performance specs never ceases to amaze me. I just don't get it. And upgrading an HO is cake, less $$, and a whole more gain for the $$. To each his own i guess. Link to comment Share on other sites More sharing options...
benjy_26 Posted April 10, 2014 Share Posted April 10, 2014 I know what happens with the ECU for sure. 89 and 90 were 182 horsepower. 91 with HO was 190 horsepower. That's a whole different animal though. The never ending Renix owners' quest and the $$ people pump into it to just equal a stock non-aspirated basic HO performance specs never ceases to amaze me. I just don't get it. And upgrading an HO is cake, less $$, and a whole more gain for the $$. To each his own i guess. Agreed.... BUT it IS kind of fun to see what little mods can pull from an overlooked system. :) I'm enjoying doing just that to my 2.5 TBI. Whenever I jump back into my 4.7 powered ZJ, though, I do get a big grin on my face. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 10, 2014 Author Share Posted April 10, 2014 Yeah. Some guys are picking up junkyard ECUs for $20. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 10, 2014 Author Share Posted April 10, 2014 Look at it this way. Your exhaust manifold is gonna need replacement anyway. Use an early HO manifold to replace it. Along with that, your headpipe is probably rusty and it has a factory "crush" in it disguised as clearance for the front driveshaft.. Have a muffler shop make the headpipe for you and swoop it so it's away from the driveshaft and has no crush along with welding in an O2 sensor bung for you. Your CPS is gonna take a dump on you anyway. Get a PC307 high altitude CPS from RockAuto. A true 60mm throttle body can be had for about $100 from www.strokedjeep.com. Stock was 52mm and the opening in the intake is 60mm anyway. BTW, the HO has a 58mm throttle body. 89 and 90 ECUs are cheap and easy to find at this point. I just don't see where the big expense is when upgrading a Renix's power. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 11, 2014 Author Share Posted April 11, 2014 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. Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 11, 2014 Share Posted April 11, 2014 A true 60mm throttle body can be had for about $100 from www.strokedjeep.com. Stock was 52mm and the opening in the intake is 60mm anyway. BTW, the HO has a 58mm throttle body. The stock throttle body opening in the HO manifold is 62mm. So you can bore out the factory "dogleg" straight through the throttle body for a free-flowing intake. Same for the Renix TB except it's a 60mm bore? Link to comment Share on other sites More sharing options...
cruiser54 Posted April 11, 2014 Author Share Posted April 11, 2014 A true 60mm throttle body can be had for about $100 from www.strokedjeep.com. Stock was 52mm and the opening in the intake is 60mm anyway. BTW, the HO has a 58mm throttle body. The stock throttle body opening in the HO manifold is 62mm. So you can bore out the factory "dogleg" straight through the throttle body for a free-flowing intake. Same for the Renix TB except to a 60mm bore? Yessir! Link to comment Share on other sites More sharing options...
JeepFanactic Posted April 17, 2014 Share Posted April 17, 2014 Where is the ECU located? Link to comment Share on other sites More sharing options...
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