notop46

I read most of the posts here concerning injector swaps and decided to look into it myself. My field trip to the local junkyard yielded three sets of four 703 injectors out of Neons. I tested all of these 703 injectors on a test bench at work. They averaged 24.6 lb/hr. (based on 30 second flow) with 3.00 bar supply pressure, 100% duty cycle (wide open), with calibrated test fluid (like gasoline, but less flammable). The spray pattern was four small streams with great atomization.

I flow tested two stock injectors from my 1990 at the same time with the same conditions, and they flowed 20.5 lb/hr. The "spray pattern" was basically a stream. The two stock injectors had a smaller flow range than the twelve Neon injectors so I know they were running fairly consistent and gave a good representation of stock flow rates.

The actual flow rating of the injectors is typically 85% of what I measured. If you swap to the 703 Neon injectors you will be able to flow about 20% more fuel than stock. This is a plus if you can pump 20% more air through your engine. If not, or you are more interested in gas mileage, then there is an additional problem with the 703s (and 784s based on supplier data).

The dynamic flow rate of the Neon injectors is 50% higher than stock. This means that the amount of fuel that is sprayed for a given injector on pulse is 1.5 times greater than a stock injector. Sure, you can reset your ECU so it “learns” how much fuel to spray for the engine conditions, but it can only do so much. Ever try to get one drop of water out of a faucet? How about a fire hydrant? Good luck. The ECU can only compute the amount of desired on time to so many milliseconds and then it rounds up or down. The injector components can only respond so fast to the signals sent to it. To get fine metering of fuel, you need a low dynamic flow rate.

I found a better set of injectors to use on my Jeep. They came out of a Jeep Liberty 3.7liter V6. They use the same connector style as the 784s Neon and stock injectors used in newer model 4.0 liter Cherokees, have the 4 spray holes, and are EV14 which is a generation newer than the EV6 703 and 784 injectors. They flow tested at 21.1 lb/hr (2.7%) higher than stock, with a dynamic flow only 24% higher than stock. They did require that I change the connectors out, but it was worth it. I have not been able to find a better match to the stock injectors than this.

I put them in without resetting the ECU and never looked back. Fuel mileage is 10% better than stock based on 12 fill-ups and 3400 miles of driving. The throttle response is definitely improved, and fuel metering is much better. Here is what I consider the best testament to how smoothly these run. Once my Jeep is warmed up and on level ground, I can slip the clutch and slowly shift through all 5 gears without ever touching the gas. 234,000 miles, 4WD, 235/75/15 tires, stock gears, 100 lbs of gear in the back, tank empty or full, 750 RPM idle going 25 MPH without chugging or bucking. Before the swap, it would start chugging in third.


More data on the fuel mileage for the skeptics: The last 12 fill-ups covered 3400 miles and took 192.4 gallons for 17.67 MPG (best: 19.54 MPG, worst: 16.43 MPG). Prior to the swap, 12 fill-ups covered 3424 miles and used 215.1 gallons for 15.92 MPG (best: 16.88 MPG, worst: 14.30 MPG). That is a 1.75 MPG improvement average. I saved over 21 gallons of gas in the timeframe since the swap at $3.15 to $3.75 a gallon. This more than paid for the swap.

I have a couple of more low mileage sets that I’m not using. If anyone is interested in trying these out, PM me. The only concern that I have in running them in a later model (1998 and later) is I do not know how these will compare in flow rate to the stock injectors. If anyone has a set of stock injectors from a later model that they want flushed and flow tested, I can find out how these stack up.

98sportjeep

Sounds awesome man!! Id love some more info on what you have to offer!!

Slick761

I'm thinkin those won't work on my 90..... and what jy did you go to to find such a new car?..... ok I read your other post. When you.changed the connectors did you solder them? The connections need to be very low resistance correct?

notop46

Soldered the new connectors to the original wires and then then shrink tubing.

xjbeans

I have see injector adapters before fyi simple plug on both ends

captainofiron

is this on a HO 4.0 or a Renix?

notop46

1990 Renix 4.0, 5sp, 4WD, 235,xxx miles. Purrs like a hungry kitten.

captainofiron

nice

it took my HO a couple weeks of driving around to get use to the Neon ones even after I unplugged the battery overnight.

when I first installed them it would take a good 30 seconds of crank, rest crank rest crank rest to get it started, now its great.

I wonder how those would do on the HO

Mendax13

aren't you supposed to cross the terminals for 10-30 seconds to drain the power from the system. and that resets it not just disconnecting the battery. and then i read youre supposed to do something with the lights when you turn it on. to reset it.

notop46

From what I understand, the HO had a larger throttle body and different ECU tuning, but no change in the injectors.

The "stock" ones I had in mine may have come from a HO. I replaced all of the original ones 3 years ago with a JY set when the originals started seeping fuel from the seems. Now I have a shiny red fire extinguisher mounted between the driver's seat and the door sill....

captainofiron

you can also touch the battery cables together to discharge the capacitors (not sure if thats what you meant by terminals)

captainofiron

may have to try that out.

I have been happy with the Neon ones so far, got them really cheap off of ebay. so its good either way

Flash1034

I put 703s in my 97. Runs great and now has a very smooth idle. Couldn't be happier.

Flash

bigvig

Out of curiosity, what was unplugging the battery overnight supposed to do, reset the computer? If so, thats not how you reset the computer so that was probably your problem. And honestly, if you havent reset your computer properly, its still not running right.

captainofiron

read a few posts below, I touched the negative and positive battery cables together for a couple minutes as well