Ive searched and searched and found some stuff on early model XJ's but pretty much no options to gain HP through the ECU or throttle body for the 89 4.0. I really want to upgrade my ECU somehow. Is it possible to flash this computer? I would really like to change my shift points as well. If there are no upgrades I think Im going to do a motor swap with a 91 or newer HO because Im so sick of never finding any upgrades for this motor. I sound real mad becuase it's the best wheelin motor ever made in my mind but really expensive to work on and really difficult to modify due to after market parts avalibility.
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89 xj ECU upgrade?
- Thread starter bluebeast
- Start date
markaboo929
NAXJA Forum User
- Location
- Mooresville,NC
you can hollow out your cat converter-if no emmisions where you are-run an open element air filter,then buid an adjustable map sensor,and you could install a spark box that controls your timing.for the trans you have a seperate computer for that-i have a 5spd in mine-no not a puke joe but an nv3550 conversion mine is an 88 xj.i can bark 33s with 4.10 gears in mine when i shift into 2 nd gear. :chef:
markaboo929
NAXJA Forum User
- Location
- Mooresville,NC
there is a write up on a switch to use for the aw4 trans just do a search.as for the map sensor do a search on this as well.i made mine from radioshack for under 12 bucks.it works very well i also forgot to mention i am using 26# injectors from an ls1 vette motor.my air fuel ratio is somewhere @13.5 but i work at a chevrolet dealer in our performance section that allows me full use of a dynojet dyno to tune on.your application will be different.as temp and elevation have factors in performance.etc...you could also slot your cranksensor some to add some timing for virtualy no cost.
markaboo929
NAXJA Forum User
- Location
- Mooresville,NC
take a good look at it and see which way it needs to"rotate" to be advanced turning it the same direction as the fly wheel turns will retard it don't do dat.when u have it out carefully mark it where to be slotted and be even where the mounting holes go so as not to let it go into the flywheel and self destruct mine has been slotted to where the outside hole is completely cut to the end and looks like no hole anymore and i rotated it to be in the middle of the bolt on that same end ,dont have pictures to show u ,that is the end of the crank sensors bracket works pretty good just keep in mind that if u use regular fuel and not premium it may ping u may have to play with it go to www.turbocity.com and look for a jeep crank sensor from them to compare yours they dont make one for the renix set up i believe or it was too much can't remember.
markaboo929
NAXJA Forum User
- Location
- Mooresville,NC
try the cranksensor trick and be amazed also
RobertF
NAXJA Forum User
- Location
- Santa Barbara
There is a high altitude crank position sensor available that has the timing advanced.
There was a $500 MOPAR Performance ECU (Long since discontinued) which featured advanced timing and increased fuel flow but required premium fuel. The hi-altitude CPS and adjustable map sensor will accomplish the same fo much less money. As far as I know Nobody can flash the Renix computer - some people claim to have modified it internally. You can get a FAST computer system for about $3400 but don't expect it to produce any more gains from a 4.0 than the stock computer. Maximum HP is controled by air flow; stock cam and valve springs is the limiting factor of that engine. I was able to develop 189 rear wheel HP with K&N, borla, hi-flow cat and Dynomax cat back with Hi-alt CPS and adj MAP. ( Not very driveable at that map setting (about 5.7V) tho.
