Own a 91 YJ with a 4.0. Engine has no modifications and has never been rebuilt. Existing Fuel Injectors have 253,000 Miles on them and I am considering replacing them.
Had seen a set of “ANSU” 1991-1995 Jeep Wrangler 4.0L I6 Fuel Injectors - Bosch 4-Hole Upgrade Set (Re manufactured, Ultrasonically Cleaned and Flow Matched) on E-Bay for about $ 109.99
(seller: lucky7injectors)
Not sure if this is the right direction to go, but any suggestions, comments, advice etc. would be appreciated.
ANSU, IIRC, is the system that they use to clean and run diagnostics on the injectors.
4 hole injectors will atomize the fuel better than the single hole style. In a stock engine, it probably wont make more than a minimal change in output at best.
Is there a reason you want to change injectors, other than mileage? On a 253k motor, there are bound to be other power issues at play, and unless your getting bogging at throttle, or miss-fires, its probably not necessary. Unless there is a severe issue with one or more injectors, your not going to pop these in and get a miraculous increase in power.
honestly if you don’t run out of fuel, run dirty fuel, neglect your engine. Your injectors should run perfectly for quite a long while. Keeping that in mind your impedence are within the 10% tolerance of the AMC 242 fuel injectors. The only reason I would change the injectors at this point in time would be to increase fuel flow and atomizations. This would be as prior suggested Nelson a 4 port or 6 port injector. The expense change is anywhere from 10 - 30 an injector more depending on your provider. Your fuel econ will change maybe 1 -2 mpg if any.
Quite honestly I would alcohol wash the fuel rail and replace the lines before changing the injectors.
Yes I have been looking at changing up to six port injectors but haven’t seen a justifiable increase for the expense.
Do you have the older style “703” (ev1) configuration that came in the 90 XJ or did you upgrade to the 784 (ev6) rail and injectors ? The 703 is the older Neon / chrysler style plugs which maxed out at 4-hole disc. The 784 (ev6) has up to 12-hole. There is minute size difference between the 2 injectors and a lot of people have found that all the needed to do was change the wiring harness.
I repeat I was unhappy with the stats for the performance for what I want to do with my XJ in the long run. It did not justify my costs of the swap.
,I WENT TO A 4 PORT AND IT MADE A HUGE DIFFERENCE IN POWER… 
AND IV BEEN LOOKING WHAT 6 PORT INJECTOR WORKS ON THE 4.0 PLEASE ENLIGHTEN ME…