So a friend and I just finished putting a fresh fuel filter as well as some new #703 injectors (thank you Programbo) on the XJ. I did some pre-swap tests to see if there was any noticible difference in these areas: throttle response, power, fuel consumption, and engine performance.

Throttle Response:

Prior to the swap, I went to friends and did some take-offs and quick accelerations. Prior to the swap, the engine would respond app. 1.25 seconds after any amount of displacement on the gas pedal. After the swap, this number became close to .5-.75 seconds.

Power:

There is a hill on the way to my house that has a relativly steep grade. I used to have to get up to 55 mph so that at the end of the hill I would be at about 45 mph without dropping out of OD. After the swap, I could hit the same hill with the same driving technique except I could easily maintain 50 mph.

Fuel Consumption:

This statistic isn't fully complete, however prior to the swap I was getting between 19-20 mpg highway and 15 mpg city. Now, if my calculations are right, there should be app. 5 gallons per white tick mark on the fuel gauge to equal 20 gallons total. I had 1/4 tank to start with after the swap. So far I have driven 15 miles and the needle has hardly moved from the 1/4 tick mark.

Engine Performance:

Prior to the swap, the engine took app. 2-3 seconds of crank time to start up. It also idled decently with little shakes here and there, however I slight gas smell came from the engine bay, however this may have been due to the rather old looking o-rings on the stock injectors. It also took about 3 minutes of driving in 40* weather for the engine to reach operating temp. With the new injectors, crank time is at app. 1-2 seconds, idle is nearly flawless, gas smell is nearly gone (what I am smelling now is the gas that dripped from the fuel rail during installation, but it is nearly gone too), and she warmed up the operating temp in about 2.5 minutes.

Overall, I am completely happy with this swap and HIGHLY HIGHLY HIGHLY recommend it to every XJ owner on this forum. If anyone has any questions, I will try my best to answer them from my swap experience.

 

nice to know. I'm going to do this on both mine and my GFs XJs here soon

 

sounds like you did a pretty good job with the comparisons can you give a better update on the mpg's once you have had them in long enough to get a good number on it thanks

 

i did mine about a month ago even if the mgp gain is not that much it the second best up grade you can do to the older xjs the first being the booster upgrade

 

yea i gotta get that bendix abs crap off mine and put a real brake booster on it

 

if im not carefull ill lock up the 38s in the rain

 

ive checked out your ride on here its sweet im running 7" right now with 33's i know i can run bigger especially with the trimmed finders i have but i have a massive amount of flex in the front of mine and like the clearance i have

 

Can you do this upgrade to a 91xj? And what type of booster should I use ?thanks ..

 

So I have had the injectors in for a good while now. I gotta say I still love em. I did the math a few times, and I am at about 22 mpg. I'm pleased.

 

Where would i buy these 703 injectors, or is the JY my best bet?

 

I have one set left. They need new o-rings which is like 7 bucks at NAPA, cheap insurance against engine fires.

I did this swap too a few months ago, didn't give me much MPG gain but did help a bit, but the idle is smoother, definitely more power (I can do the speed limit on the highway now without flooring it!) and even when its below zero, it cranks for half a second and starts right up.

 

Are you guys resetting the ECU after replacement?

 

So is this pretty much plug and play?

 

As long as you get the correct ones... I found a pretty detailed place on Ebay that's selling sets of 6 for $150. He has a pretty detailed explanation and p/n break down.

search for "Jeep cherokee injector upgrade" and it'll come up

 

wow if it takes your engine 1.25 seconds to response to you pressing on the gas pedal something is seriously wrong... i really don't see that happening lol