xjbuddy

i recently did the fuel injector swap on my 98 4.0L. its been almost a month now and i havent noticed any differences in my mpg's.. is the swap a hit or miss with different XJ's. my rig is not lifted at the moment and running on 30's. any ideas on what i did wrong???

xjoffroad

what injector swap did you do?

93gc40

I'll assume you have a Stock Cherokee with 4.0, because you ask on this site. But, without any info on your Jeep it's kinda hard to offer any help.

xj_maniac_newb

? im on this site too, and i haz a 4 banger

and yes what swap did you do? the mustang injectors? only other one i know of is only for 96 and down cherokees

89Laredo

Did you reset the ECU?
If not, do it. It would be using old fuel maps.

xjbuddy

S,I did the neon injector swap for the 97+ model XJs. Like in the forum that has been floating around here. If im not mistaken they are the EV6 type injectors.. and no i dont think i did reset my ecu. Call me stupid, i dont think i know how either. Am i just disconnecting the battery cable for a while??

89Laredo

Just disconnect the battery cables for a while, pry half an hour or more. Turn the key "on" and push the horn button, then reconnect your battery.

It will act weird for a couple days, and you may lose MPG but it will come back. The ECU has to build a new fuel map, this usually takes ~50 key cycles.

davida

If you don't do this won't the ECU build a new fuel map anyway after the next 50 key cycles?

93gc40

Yes it will, but the new maps will be based on the old maps and components. You need to make the ECU forget its history to get the correct new mapping.

89Laredo

The fuel maps are set, after 50 cycles they do not change.

Its that way for Renix at least.

Tural

did you clean the injectors before you put them on? can you tell me all of the steps you took and where you got the injectors from and the id number on the injectors?

xjbuddy

Sure did, cleaned them well and got all new o rings for them too. I got the injecter from my local JY. I cant seem to find the injectors id number, i wrote it down somewere. Go to the search box and punch in injector swap. There is a very popular thread floating around that explains it better than i can. As far as i can tell its worth it. IMHO..

Tural

no i was trying to help you out. i got almost 2mpg better with the injector swap and 63mm tb. you are supposed to cycle fi cleaner through the injectors. actually hook up 12V to each injector and run fi cleaner through them at high pressure. btw the number on the injector is supposed to be 0 280 155 703. i just wanted to make sure that you got the right injectors.