Curtis Robinett

First time Jeep owner and I keep hearing about upgrading injectors for better throttle response and milage per gallon. I live in Bethel Alaska and gas prices are sitting at 5.119 a gallon! They just lowered the price too. Anyways I do just basic day to day driving but sure would like the extra power to go with the better mpg. My Jeep is all stock except for a 2 inch lift and tires of course. Tires are only 235/75R15's. Any advice on an upgraded injector type will be greatly appreciated. Thank you. Curtis

Chick-N-Picker

Hey. I know this one. If your injectors have square wire connectors the best are 746's that come out of 93-98 volvo's 850's or 90 series mainly (few other models too). They're best for a couple reasons.
1. They get better gas mileage. How much is disputed but you should see a gain.
2. Most importantly XJ's have a two piece injector which is prone to leak at the seam. 746's are one piece and should leak at the body ever, unless it somehow gets cracked. If you use those and leaking occurs it's mainly the orings which are an easy cheap fix.

Now, you can order used volvo 746's fairly cheap off ebay or go to a junk yard if you need them quicker and see if they have any volvo's.

Most volvo's these came in have 5 injectors and a few have 6. I got lucky and found a 6. If you go the JY way they are very eay to take out. About 5 bolts/screws if I remember.

The orings you need to get are the same ones you can get at auto parts store for your stock jeep injectors.
Hope that helps.

PS adding your year jeep, motor, auto/straight, and whether it's 2wd/4wd will help everybody answer faster. That way they don't have to wait. They can jump straight to helping you out.

Curtis Robinett

Sorry for not stating what my jeep is.
1990 Cherokee Pioneer
4.0, auto, 4×4

Fred/N0AZZ

A newer style injector will help with a smoother idle and throttle response but don't count on better MPG's with them alone. How long has it been since you have done a full and complete tune-up? That may help the most.

jhc7399

What Fred said!

Not everyone gets better mpg's and there is no way to tell until you try it.

The 746's are the ones you want for that year sir.

Chick-N-Picker

Very true. That's why I said it's no way to tell how much. I've seen people say they got maybe .5 more per gallon and I've also seen people report 9 per gallon!!!

I'm sure the 746's help (possibly significantly) but a good TB and AIC cleaning should also be done. Correct reading o2 sensor......etc can also factor in.

PS I personally can't say because I currently doing an exhaust manifold gasket with 746's so, if I see any improvements in mpg. I'm sure it will come from all I've done and not just injectors. If I would happen to gain 5 mpg+ with all I've done, I would be happy! Haha

1. 746 injectors
2. New, not leaking EX gasket.
3. New down pipe
4. TB and IAC cleaning
5 . New vaccum harness.

I will not be running a cat, muffler, or tail pipe until next month sometime though.

PNWjeeper

I've got to say I've got a set of the 746's in my Cherokee and although I haven't gone through a full tank of gas yet, jeep barley gets driven since work provides a vehicle, I'm actually getting worse MPG. I used to get about 250 miles to a tank or roughly 13 MPG, I'm currently at 180 miles and my gas light is turning on and off (gauge is really easy for me to read but no one else, it says tank is full until down to about 1/4 tank of gas then will shift its way over turn the light on then move back and turn the light off this takes progressively longer the less gas in the tank).
HOWEVER I do have a cracked exhaust manifold obviously leading to false O2 readings causing the new more efficient injectors to use more gas trying to balance out the mixture, once I make my way through this tank of gas I fear my O2 sensor will become inoperable in an attempt to see if that changes things. At my current rate of driving the jeep this could take another year to confirm lol.

Big David

Yeap. My exhaust manifold was literally in pieces. I was getting 10 mpg. I swapped in a used one & instantly went to 15 mpg.
Why is there no aftermarket upgraded exhaust manifold for the Renix?

PNWjeeper

SERIOUSLY right? I know you can get the 91+ to work but it would be nice to have one for Renix.

Chick-N-Picker

I am replacing my Ex manifold gasket and had to get a crack welded. I really really hope it holds up for a while but I know at some point, some day it will crack. I just hope it's 5 years and not 5 months.

PNWjeeper, your the first guy I've read to get worse MPG with 746's but maybe it's due to your o2sensor. Let us know what it goes to after the fix, if & when you get around to it.

Curtis Robinett

Thanks for the info guys. I have already done the full tune up except for swapping the O2 sensor out. It does have a slight exhaust leak under the hood. My best bet would be changing the manifold gasket and check to see if there are any cracks on the manifold itself. Now I know what to look for. Thanks again.

cruiser54

The following is pretty much what most go by when replacing Jeep injectors.

87-90 4.0 - Bosch 0280155746, from Volvo's.

91-98 4.0 - Bosch 0280155703 from late 90's dodge Neons and few others. Some people use Bosch 0280155710/0280155700, From old Ford V-8's if I remember correctly.

99-04 4.0 - Bosch 0280155784 from late 90'sand early 2000 Dodges Neons as well.

The 703 and 784 have a different plug, same injector.

Curtis Robinett

Thanks. It will be pretty hard to find something like that around here so I think finding reman injectors would be the best solution. I guessing ebay? The injectors I have are the two piece and have a big square 2 wire plug.

Another question is which do any of you prefer to cleaning an oily dirt and dust covered motor with? Engine degreaser? Hot pressure washer? Any leads will help me on getting this thing up to par with better efficiency. I really like this Jeep and would like to keep it in top shape. Thanks again guys.

cruiser54

Welcome to Cherokee Forum Shopping Network:

http://www.ebay.com/itm/Single-Unit-...-/252078956862

BMAC6642

I have these Pace long tubes waiting in my garage to install on my 87. Bought them from Morris 4x4