10% MPG Improvement + Better Drivability
10-21-2011, 09:50 PM
#31
Only one way to find out then lol.
I think I had found a website that had the injector stats but now can't find it. I think it was something 5.o or similar, it is a place that sells remand injectors
I think I had found a website that had the injector stats but now can't find it. I think it was something 5.o or similar, it is a place that sells remand injectors
10-22-2011, 09:18 AM
#32
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Year: 1990 - 2000
Model: Cherokee
Engine: 4.0
I have a spreadsheet with most of the bossch injecters, but no good info on the stock latemodel 4.0 injectors. If I get a couple, I can test them. I guess a trip to the JY is comming soon.
10-24-2011, 06:24 AM
#34
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Year: 1990 - 2000
Model: Cherokee
Engine: 4.0
See Injectors For Sale
I have a couple of sets of 6 listed in the For Sale Forum:
https://www.cherokeeforum.com/f11/be...ectors-109444/
They can also be found on ebay for $25+ each:
http://www.ebay.com/itm/Dodge-Jeep-M...item4cf74e0bc1
You would still have to splice in USCAR injector plugs that are found on later model Jeeps 2000+, Neons with 784 injectors, and many other late model cars. The alternative is to buy a set of adaptors from Jetronic to USCAR. I located several sets on e-bay:
http://www.ebay.com/itm/FUEL-INJECTO...item2eb88d0e44
Let me know if I can help with additional information.
https://www.cherokeeforum.com/f11/be...ectors-109444/
They can also be found on ebay for $25+ each:
http://www.ebay.com/itm/Dodge-Jeep-M...item4cf74e0bc1
You would still have to splice in USCAR injector plugs that are found on later model Jeeps 2000+, Neons with 784 injectors, and many other late model cars. The alternative is to buy a set of adaptors from Jetronic to USCAR. I located several sets on e-bay:
http://www.ebay.com/itm/FUEL-INJECTO...item2eb88d0e44
Let me know if I can help with additional information.
10-24-2011, 01:03 PM
#35
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Year: 1999
Model: Cherokee
Engine: 4.0
if i had another vehicle to drive i would send you my 99 injectors to see what the flow rate is. i get about 13 miles a gallon but i drive like a jackass
and want to see what the difference is on a new set.
cheers buddy and nice write up.
and want to see what the difference is on a new set. cheers buddy and nice write up.
10-24-2011, 01:14 PM
#36
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I still get 18 to 21 on the HWY and my INJ. are a hodge podge
2 new stock inj. about 5 years old now
2 of the origional ones going at 422,000 miles
and 2 off of a 90 something LeBaron
think a new set might do me some good
2 new stock inj. about 5 years old now
2 of the origional ones going at 422,000 miles
and 2 off of a 90 something LeBaron
think a new set might do me some good
10-24-2011, 03:55 PM
#37
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Year: 1996
Model: Cherokee
Engine: 4.0
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.
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.
10-24-2011, 08:44 PM
#38
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Year: 1990 - 2000
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Thank you. If I can ever get to the JY, I will try to get a couple to test.
10-25-2011, 12:23 AM
#39
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Year: 1996
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Great info OP! I've been reading a little on this topic lately and your write up is the most informative I've found yet. I get about 16mpgs now, but have only had my xj for 3 weeks. I'm catching it up on the routine maintenance and think this is something I'm going to try.
Last edited by hytek; 10-25-2011 at 12:37 AM.
10-28-2011, 05:49 AM
#41
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Year: 1990 - 2000
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Did you have problems with the original ones leaking fuel out the side? Mine leaked. Now I have shiny red fire extinguisher mounted between the driver's seat and the door. :-)
10-28-2011, 12:49 PM
#42
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Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Usually a problem with early xjs with two piece injectors. One reading the 5.0 injectors are a good upgrade if they're cheap.
10-28-2011, 01:22 PM
#43
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Year: 1990 - 2000
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Yeah, I had a few leaking at once. I could smell the gas when I got out, but could not see a leak under the jeep. I checked the fuel system and found the injectos were wet. Installed the fire extinguisher and went to the JY to find replacements. Do not mess with fuel leaks. A friends wrangler went up in flames 2 minutes after walking inside.
I have a stock engine and do not need the extra fuel that the 703s would deliver. I swapped in the 021s and literally drove away. No retune required.
I have a stock engine and do not need the extra fuel that the 703s would deliver. I swapped in the 021s and literally drove away. No retune required.