Hi All,

I have been reading the posts here for a while on the topic of swaping in the 2.4 liter Neon Injectors Bosch # ...703. So this weekend, I just picked up 3 sets of 4 @ the local junk yard. In the process of flushing and flow testing them, I became concerned that the flow rate of these injectors is too much higher than the flow of the stock injectors to help with my gas mileage. I can see the better spray atomization when comparing to stock, but going from 20.5 lb/hr (2 stock tested at 3 bar supply pressure, Room temp, 14 V @ injector, 100% DC, calibration fluid) to 24.5 lb/hr (12 tested, same conditions) for the ...703 injectors seems like a huge adjustment for my OBD1 Cherokee's computer to make.

It is possible to adjust the fuel pressure down by ~ 20% to get the proper delivery for the same injector on time? I know this will reduce atomization, but I can not think of a better way to get the flow rate where it needs to be.

I would like to hear from anyone who has made the 703 injector swap and has real data to backup their findings.

Thanks David

 

Don't know what's up with your testing but the stock injectors and 703's should only be running at 19lbs/hr at 12ohms. You may want to make sure everything is correct.

 

They flow at the same rate as the stock injectors, they just have four holes instead of one to push the fuel through. I did the swap and noticed no drop in my fuel mileage. The only thing that I noticed was a smoother idle and slightly better throttle responce.

 

x2 no loss in mpg much better idle and quicker throttle response

 

Thanks freegdr, Bustedback,

Is the ECU reset the same for a 1990 as the 703/784 injector swap write-up?

 

i did nothing with my ecm just swapped and went mudding were both renix

 

That is good to know.

Any thoughts on lowering fuel pressure 20% (or tricking the RPM signal to the ECU)?

I may try to find a set of injectors that meet all of the dimensional requirements, have the same inpedance, with closer flow rates even if it means that I have to swap out the connectors. I found a batch of prototype EV14 (the latest generation low pressure Bosch fuel injector) in my desk at work.

 

just install the injectors and be done with it. There is no need to screw with the pressure or reset the PCM, just install them and then get on with your life.

 

This is my life. I spent the last two weeks looking at fuel rails from a supplier with a bad braze joint on the Schrader diagnostic port wondering and then testing how much a bump it will take from a slipped tool or dropped part to cause the joint to fail and start leaking fuel. Tweaking my fuel pressure or picking a better injector so that my Cherokee doesn't have to go back to Kindergarten is the best part of my life.

 

Search for the injector thread I started... there is a ton of technical info in there... if you want less then the 703's then run the Ford 19lbs... I dunno why you would want less but go ahead with it... I noticed nothing with the fords on mine... going 703's one of these days... you would be surprised what your ecm will do... I ran a HO motor with 91 plus throttle body on a renix wiring and ecm... ran great!

 

i know this thread is a year old but i just was looking at the same thing with the same questions. on top of that the topic comes up frequently.

here are a few facts

Model Year, ...Part #, ...........Colour, .....Fuel Pressure, ...Static Flow,
'87-'90, ........53003956, .........Black, ...........39psi, .................18.6lb/hr
'91-'93, ........33007127, .........Brown, ..........39psi, .................21.0lb/hr
'94-'95, ........53030343, .........Tan, ...............39psi, .................21.0lb/hr
'96-'98, ........53030778, .........Grey, .............49psi, .................23.2lb/hr
'99-'04, ........04854181, .........Blue tip, ........49psi, .................22.5lb/hr

the 703 injector, depending on the page quoted flows 22.7 to 23lb/hr at 43.5psi {still looking for actual test data to confirm this}

at 39psi it will flow 21.5lb/hr
at 49psi it will flow 24.1lb/hr

the reason i bring this up is that it becomes fairly clear the only cherokee that the 703 is a direct fit into is the 91-95 model years. they probably work alright in 96-98 but are going to be rich at WOT. the ecu should be able to pull fuel at part throttle however. for the early renix models the ford 19lb injectors would appear to be the best fit as the flow is nearly identical.

i have no idea what injector to use in 99+ as neither the ford 19 or 703 would be a good choice. i suppose a person could backdate and install a 39psi regulator and use a 24lb injector at 43.5psi and get really close to the factory 22.5lb flow

anyway, i just thought i would list some math in one of these injector threads