It may be because you reset the ECU. When you do that, it defaults to a rich setting until it re-learns how your engine runs under different load conditions. The re-learn is based on feedback from the O2 sensor. I have read that it takes up to 50 cold start cycles to perform this before it stabilizes.

Having studied output data from a narrow band O2 sensor like we have, I can tell you it takes a while to hit all of the load conditions and get enough data to make good adjustments. I went through 5 tanks of gas on my Chevelle dialing in the EFI and still only reached 12.5 MPG on the highway. Similar problems to a Jeep: heavy, as aerodynamic as a brick, and an engine/drivetrain that was not designed for fuel economy.

My recomendation to anyone trying these injectors is NOT to reset the ECU UNLESS you are replacing higher flowing injectors (703/784). Swap injectors, start it up, and see how it runs. If it seems lean or the plugs look chaulky white after 30 minutes of driving, then consider resetting the ECU. You can expect it to run rich and get poor gas mileage until it re-learns.

 

any new updates on these injectors. i have some 703's available but if these are closer to stock and i'm not "wasting" fuel for power adders i don't have i'd rather find some of these and throw them in.

 

ADDED/EDIT. Yes, 703's
I just picked up a set, haven't installed them yet. Unfortunately my mileage shot up to 18-19 on the 1,500 mile trip when I got them! (was 15 +,--)(90, 4.0-265K!). So it will be a week or two, I keep good records, I'll post the result of the swap in this thread.
........................VVWHOOPS, WRONG!VV
If I read right they flow 2% more. I gather the 02 sensor/ecm will trim that down to the ideal 14.7 ~ 1 ? With 4 holes and better atomization I guess I might expect smoother running/idle, better throttle response, and maybe better mileage.

Anyone, if you go to the JY, take a lens and a good light! Forget the ones that are not black. Forget the ones with a red clip on the left. You want "squinty eye" headlights. I forget, one was a LaBaron, or a Seabring. 9 out of 10 Neon's didn't have them, (in Windsor).

 

Those look to be 703s, and 703s will flow about 10% more than stock. An ECU reset will definitely be needed.

I'm still rocking the 021s and loving the better mileage and driveability.

 

Crap. Don't tell me I screwed up. Yea, 703's. I'm a 90 Renix. Reset?

 

I had been waiting to hear how the swap was going notot. Seems like the swap is legit on your ride. I want to do this on my 98.

Is it the 703's that fit on to a 98?

 

Have you guys tried Rochester 17103146 injectors out of a 1996 or newer 3.8l v6 gm? They are rated at 21.2 lb/hr and feature a 6 hole pattern. I just swapped some in and have been really happy with them. I wish I could compare fuel economy but I switched tires at the same time.

 

Definitely reset ECU

Depends on what connector your injectors have. I beleive that 98 is the year that they switched injectors and connectors. If it looks like the ones a few post earlier, the 703s will fit.

 

Yeah mine are not the connectors on the 99, just worked on one this last weekend.

 

Hey all. I have a 98 also. If I read right, the 021's (liberty) injectors do not need a connector change or ECU reset, correct? Also, found these on Ebay and showed compatible vehicles. Basically all Jeep & Dodge w/the 3.7 V6. Leave it to better brains to confirm.


http://www.ebay.com/itm/Mopar-530327...=mtr#vi-ilComp

 

I dont quite get how the neon injectors flow more than the stock injectors.

Neons flow 238cc @ 43.5 psi

91-95 flow 248cc @ 43.5 psi

renix 87-90 flow 240cc @ 43.5 psi

 

I'm not actually disagreeing with you, Just wanted to mention a bunch of Neon's I looked at didn't have 703's, and Renix has 31 at idle. 39 when you pull the vac line to the fuel pressure regulator.

 

Sorry, I was mistaken. The Neons flow closer to 20% higher flow rate than stock injectors. I flow tested both of them at the same time on the same setup (12 volts, 3 bar pressure, full on for 30 seconds) and the stock injectors averaged 77.7 grams and the Neons averaged 93.0 grams. There was less than 1% measurement variability between the stock injectors.

If the Neons were the same flow rate as stock, you could run them without resetting the ECU.

 

what about these?
http://www.ebay.com/itm/4-0L-JEEP-CH...19427703676644

 

I'm curious as to how you are determining when you are in "open loop". I ask this because I am trying to learn these Jeeps as a new owner. My ScanGauge 2 shows both my 96 OBD2 Cherokee and my 2006 Honda DD going into closed loop quickly, before I even make it out of my driveway.

I would like to improve my mpg with a swap. When I fire up the jeep, it's going the 50 or so miles to work on rural country roads. Few stops just 45-60 mph cruising through the rolling hills of Virginia.


Thank you