Topic: cherokee ecm swap?

[bigcountry333]

ive been doing a lot of reading on the 2.5 lately. seems that the cherokees from 91-95 were rated 20 hp higher than the wranglers. cams are the same so that leaves the ecm's. i would assume the ecms are different because it would be illogical for anything else to be diff.

[sharpxmen]

ive been doing a lot of reading on the 2.5 lately. seems that the cherokees from 91-95 were rated 20 hp higher than the wranglers. cams are the same so that leaves the ecm's. i would assume the ecms are different because it would be illogical for anything else to be diff.

the difference was 9HP and 4ftlb of torque, and you're right it's the PCM fuel curve in open loop that probably was the reason. You can compensate for that with more fuel (pressure or injectors or both) and no need to replace the PCM. I'm not sure if the airbox was different or not in terms of the restrictor tube you find in the YJ airbox in the outlet - that could also limit the output of the engine, most guys already removed that and went to a 4.0 t/b if not larger.

[bigcountry333]

thanks, kinda figured the figures were a little massaged.

[sharpxmen]

thanks, kinda figured the figures were a little massaged.

compared to the carburetted one was 25HP more. One difference though, apparently in the XJ version compression was a tad higher (not by much, i can't confirm but probably depending on the pistons could have been 9.2 or 9.4, or maybe a thinner cyl head gasket), YJ was at 9.1:1

[chardrc]

yj mpfi 9.1:1
xj mpfi 9.2:1 91-95
tbi all 9.2:1 87-90

according to allpar

http://www.allpar.com/mopar/amc-25.html

[sharpxmen]

yj mpfi 9.1:1
xj mpfi 9.2:1 91-95
tbi all 9.2:1 87-90

according to allpar

http://www.allpar.com/mopar/amc-25.html

I saw that but if you look at replacement pistons they are from 9.2 to 9.4 resulting CR based on dish volume and compression height, so that's why i said i'm not sure.