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can i use these?

W

wingnutooa

NAXJA Forum User
Location
Nashville TN
dinp-066.jpg



not sure how to convert the flow to compare it to the injectors i currently have...


found this on nagca via google search :

As for injector flow rate I believe the Renix 4.0L (87-90) used 19.7 lb, 91-95 21 lb injectors, and 96-up 24 lb injectors. Not real sure on some of those but I do run 19.7 lb ones in my stock Renix 4.0L XJ.


i have both renix injectors and 91 injectors due to a HO swap in my 87.

i recently installed the renix injectors in my jeep to try and save fuel mileage and now, hot warm or cold, if i shut the jeep off, say to get gas, and start it back up it will start to die and rev back up by itself.

it does this about 6 or 7 times in a span of a few minutes before its safe to pull out into traffic.

i am going to swap the injectors back out to the HO injectors but i just did an engine swap in a 99 caravan and pulled these injectors out.

so just curious if i can install them. i know there is a low impedence high impedence thing so i figured i'd ask first.
 
You should keep your stock injectors in there.

If you run a lower flow injector, your computer will see that you are lean, and increase the pulse length to compensate.. and from there its all downhill.

If you want to increase economy, take your foot off of the pedal or buy a hyundai.
 
ok so which ones are my stock injectors? the ones for the HO motor in my jeep or the renix ones that match the computer.




i AM going to change injectors because its running poorly, and was not before.

i just wanted to know if these are an option.
 
the motors are more or less identicle (there are some head and cam changes but they dont matter in what we are discussing).

dont think about your motor as an HO motor, as far as you are concerned it is all renix.

also, iirc, all of the xj 4.0's use 19 pound injectors. the later HO's have higher fuel pressure, and run a shorter injector pulse to get the same amount of fuel in the end. those injectors aren't designed to run at the lower fuel pressure of a renix jeep.


if you wanted an upgraded injector for your renix system, the ford mustang 19 pound injectors arent a bad choice, but stock should be fine.
 
wingnutooa said:
i found a calculator and it seems that these from the caravan are 20.2 lb/hr
Click to expand...

at what fuel pressure?

its pounds / hr @ pressure, not pounds / hr.

You will be running 31 psi @ idle, 39-40 psi @ WOT.
 
I do have some 19# volvo injectors-same as ford-BUT have the slot for the clip to hold it on the rail...I run these same injectors in my set up-22003 WJ 4.0 ran by a Renix ECM I did however use the returnless system which is 49-50 Psi-those injectors are rated at the 3 bar 43 psi-They work real good and have no problems.
 
Last edited by a moderator:
i changed them out and it still does its dying thing.

i guess i'm just going to put the HO injectors back in. it ran fine with those.

and it is 212cc/min @ 3 bar if that helps the conversion.

when i put it in the calculator it came back with 20.190~ which would make it 20.2 lb/hr @ 3 bar.

i can't remember what 3 bar is though.

the caravan injectors and the HO injectors both measured 14.6 ohms and the renix came back with a 16.7 reading.
 
i think you're chasing your tail, and that the injectors are not your problem - but that something new has gone wrong. ;)
 
ok now i'm reading that a renix injector is rated for 39 lb/hr @ 3 bar and the later 4.0's at 49#

so if these caravan injectors are only 20.2 that means i went in the wrong direction.
 
after i did the high output swap it ran fine for almost two years, untill i decided to put the renix injectors in.

then every time i start it, it wants to die for a couple minutes.

that symptom started immediately after the swap.


and if you have any other ideas about what is causing my problem i welcome the help.
 
Last edited:
I'm not sure why you had better luck with the HO injectors-- if the ECU, fuel rail and regulator are from the Renix, you shouldn't have any problem using them (since they're designed to work together)
 
so if i shouldn't have any problem running any of these three injectors, does anyone have any idea why my jeep is doing this.

maybe a place to start? i have already changed the IAC valve.
 
i hope youre doing the calculations right. all injectors are rated at cc/min @ bar or lb/hr @ psi. if youre looking at 212cc/min @ 3 bar, thats 212cc/min @ 33.5 PSI. you need to make sure youre comparing apples to apples and that you dont have a pressure difference youre trying to compare across. This HAS happened, I have seen people believe two injectors are different based on cc, but they were just the same rated at 3 bar and 3.5 bar (different applications).
 
cal said:
also, iirc, all of the xj 4.0's use 19 pound injectors. the later HO's have higher fuel pressure, and run a shorter injector pulse to get the same amount of fuel in the end.
Click to expand...
Not quite

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-'99, ........53030778, ...Grey, .........49psi, .................23.2lb/hr
'00-'01, ........04854181, ...Blue tip, .....49psi, .................22.5lb/hr
 
Hoooper said:
if youre looking at 212cc/min @ 3 bar, thats 212cc/min @ 33.5 PSI.
Click to expand...

3 bar = 43.5psi. Not 33.5 psi.

OP:
Those caravan injectors work out to 17 lb on the 39psi renix fuel rail.
HO from 91-95 would be 21 on the renix rail (same pressure).

The Caravans would have been a poor fit as well as the pintle end having a quite different style from the Jeep injectors. I don't know the history of the injector you installed, but it they sat for a good length of time unused they could be clogged.

As Cal said before changing injector flow rates won't help your mileage one bit. What might help is finding a set of multi hole injectors. I would go with new, rebuilt or ones that have been cleaned. Salvage and ebay used ones can be hit or miss for ones that actually work.
 
Talyn said:
Not quite

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-'99, ........53030778, ...Grey, .........49psi, .................23.2lb/hr
'00-'01, ........04854181, ...Blue tip, .....49psi, .................22.5lb/hr
Click to expand...

Hm.. I can't be perfect every day. :)

good data there.
 
ok so i was right in my conclusion that the caravan/mitsubishi injectors actually flow less than renix.

the end is slightly different but slides right into the hole in the intake. was a little difficult to install but it does run fine once it stops trying to die.

as soon as i get a free day i'm going to throw the HO injectors back in.

the only problem i had with those was sometimes on startup it would idle up, sometimes beyond 3,000 rpm and stay there.

wouldn't come back down untill i shut it off and restarted, and sometimes it took a few tries at that.

as soon as i put the renix injectors in it stopped doing that and started trying to die after startup.

if it starts revving high again after i put the HO injectors back in, atleast i will have some sort of consistency in regards to symptoms.

i have changed the IAC just because i had one laying around.

the 3.0 caravan engine actually uses the same IAC valve though the plug angle is slightly indexed clockwise.
 
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