JerseyboyXJ

My 849 (XF1E-A5B) injectors came in the other day for the swap on my 2000 XJ. I know I have to reset the computer to factor so it can adjust to the new injectors. I've read that you disconnect the negative cable and touch it to the positive cable for 30sec. then connect it back, key forward, lights on lights off, key off and done. First 50 starts will be a little rough but no worries.

heres my question... if I connect the negative to positive cable and the positive cable is still connected to the battery it will spark like a mf'er. Is this what I'm supposed to do anyway or use common sense and disconnect the positive cable as well before connecting the two cables?

freestylr2525

disconnect both cables completely from the battery.

kyledye25

I wouldn't. I did with mine and regret it. My mileage went way down for many tanks. Seemed like it took forever to get back to where it was. And I'm really not getting better mpgs. Everything else improved. So I'm happy. But my mileage went from 16 city down to 12. Then next tank or two 13. And so on. I guess I thought is see better mileage sooner. O well. Still very happy with the swap.

kyledye25

But if u do reset it its like hold them together for 30 secs then turn the headlights on and off...somehing like that. I don't think just taking the cables off will reset the computers back to learning stage.

ikenchute

take the positive cable off the positive battery post and hold it to the negative post there is no way it will spark.
hold for at least 30 seconds, hook positive cable back to positive post, then do the rest of the stuff...key on, headlights on, headlights off, key off an you're done.

now ya just have to drive it like normal for a while so it will learn you're driving habits. so don't worry about the mpg for i'll say 3 full tanks then start keeping track to see what you really get.
provided you have the right tires, gears and speedo gear to get a true reading.

JerseyboyXJ

thanks for the help. my big issue is a cylinder 3 injector malfuction on the OBDII code reader. Instead of just throwing one new injector in with five older injectors I figured this was a chance to upgrade... really going for the smoother idle and throttle responce. I dont really see how a 4 spray injector gets better mpg then a single shot injector that has a smaller cc rating. 265cc @ 43.5psi (new 849 injector) compared to 236cc @ 49psi (factory injector) both a 24lb injector tho.

99 Purple XJ

The 4 hole injectors are smallee thus vaporizing the fuel better instead of a solid gas going into the cylinder the more the vapor the better it lights when spark hits it

JerseyboyXJ

Cool thanks for clearing that up. Didn't think of it in that sense.