Injector upgrade thoughts. - AUSJEEPOFFROAD.COM - AJOR


Portal Register Forums Trading Your Jeep New Garage Mark All Read

Post New Thread  Reply
Thread Tools Search this Thread
Old 30-12-2009
rainman's Avatar
rainman  rainman is offline
Rock Munki
Join Date: Mar 2008
Location: Kellyville NSW
Posts: 2,265
What Jeep do I drive?: XJ
Likes: 140
Liked 280 Times in 167 Posts
Default Injector upgrade thoughts.

Injector upgrades.

Here is some info about Injectors posted on the Cherokee forum by warpath4x4 and coas in early/ mid 2009. I have made some minor changes for clarity however the below the link takes you to the original thread.
I have also added other stuff from other sources, and most of the pictures.

87-90 Cherokees have a jetronic/minitimer/EV1type injector electrical connector
90-93 Cherokees have a jetronic/minitimer/EV1 type injector electrical connector
94-95 Cherokees have a jetronic/minitimer/EV1 type injector electrical connector
96-98 Cherokees have a jetronic/minitimer/EV1 type injector electrical connector
99-2001 Cherokees have a EV6/USCAR type injector electrical connector

What you have:

'96 onwards have 49 PSI on the fuel rail constant.
'99-'04, .........4854181, ...Blue tip, ....................22.5lb/hr@49psi(236cc/min@337KPa)=21.14Lb/hr@43.5psi (222cc/min@300kpa)

'96-'98, ........53030778, ...Grey, .......................23.2lb/hr@49psi(243cc/min@337KPa)=21.71lb/hr@43.5psi(228cc/min@300kpa)

Pre 96 the fuel pressure is lower and variable 31PSI @ idle& 39 PSI at wide open throttle.
'94-'95, ........53030343, ...Tan, ........................23.61Lb/hr@43.5psi(248cc@300kpa)

'91-'93, ........33007127, ...Brown, ....................23.61Lb/hr@43.5psi(248cc@300kpa)

'87-'90, ........53003956, ...Black, ......................22.8Lb/hr@43.5psi(240cc @300kpa)

Thease all black "RENIX" injectors are stated in a number of places on the web as having a flow rate of 18.5lbs/ hour.
However when coas tested them on a professional injector test bench he got figures of 22.8lb/hr@43.5psi(240cc/min @300kpa) which would flow about 21.5lb/hr@39psi. Hence that is the figure we are going with here.

EV1.3 Ford injectors
Rated at the same pressure and with EV1/ jetronic electrical connectors, Have been a popular choice as an upgrade:
Ford Motorsport 19.0lb/hr @ 39psi (Part no. FMS-M9593-C302)

Ford Motorsport 24.0lb/hr @ 39psi (Part no. FMS-M9593-A302)

Ford Motorsport 30.0lb/hr @ 39psi (Part no. FMS-M9593-B302)

little math.
Injector size (lb/hr) = (horsepower x 0.5)/(no.of cylinders x 0.8 )
So say you have a 250 horse I6...
125/4.8=26 lb/hr injector

So for a 30 lb/hr injector, you would need about a 290 horse motor to utilize them.

Cherokees from 93 on made around 190hp stock= 19.8 lb injectors according to the above formula

The 24lb injectors should be good for some 230hp.

Ev1/ EV1.3 injectors worked OK but EV6 is better

The EV1 (pintal type) & EV1.3 4 hole injectors are inferior to the newer EV6 injectors for a number of reasons.
1) EV1&1.3 injectors can only be used at their nominal design pressure. Ev6 injectors can be used over a wide range of fuel rail pressures.
2) EV1&1.3 injectors are made of metal and plastic, which can leak or even brake at the join, and due to the metal are more prone to heat soak, Ev6 injectors are constructed of a single plastic casting.
3) Response time of the EV6 injectors are quicker than the older designs. Atomization of the fuel is also better / more complete.

Extract from bosch fuel injector pamphlet:

Effects of Fuel Pressure on Pintle Type Fuel Injectors.
Fuel velocity through a pintle type fuel injector [type code EV 1] can dra-
matically affect its ability to atomise fuel. The profile of the pintle used in a
fuel injector has a direct relationship to the operating pressure it is designed
to operate under. Whilst Bosch produce various fuel injectors that may flow
the same amount of fuel at a given specification, the system operating pres-
sure will influence the pintle profile. Correct pressure will result in a well
atomised spray, while insufficient pressure will result in a “hosing” effect.
Excessive pressure will result in either “hosing” or a spray angle that is too
large for the targeted area dependent on the pintle profile.
The consequence of excessive fuel pressure on a pintle type injector may
well be that as the pressure is increased the mixture values of the engine
may appear to get leaner. This is of course not the case, but the fuel being
injected is no longer atomised and is entering the cylinder as a liquid mass.
This will typically cause the Hydrocarbon [HC] values to rise due to the raw
fuel exiting the cylinder, and the Carbon Monoxide [CO] to drop due to
insufficient combustion.
Later design fuel injectors [type code EV 6] use “director plate” multi-ori-
fice technology to better atomise fuel across various operating pressures.
These injectors allow more flexibility in relation to operating pressures with-
out compromising spray efficiency or fuel atomisation.

EV6, multi-orifice/ director plate, injector end

From coas:

EV6 multi hole injectors are better alternative than the above mentioned ford EV1.3 injectors for 4l jeep engines, Renix should use the same flow injectors as the HO, the stock injectors for Renix flow 240cc, HO flow 248cc (up to 95-OBD1) and 234cc (96- up OBDII). However, the Renix and OBDI flow at 39PSI and the later OBDII ('96 onwards) flow at 49PSI.

Note -The Renix mpi system was never sold in Australia -

Injector flow is always measured at 3 Bar, 43.5PSI. This is a reference point and from this you can calculate the flow to your system working pressure.


So, why not "yellow stick" #19 Ford Bosch 0280155710 injectors? (same injector also has part numbers:F4SZA, CM4768, F4SEA1B, 0280155710, F6VZ9F593AA, F5VZ9F593AA, 0280155700, CM4809).

Because stock XJ injectors flow more than 230cc, and these flow about 210cc, and don't have a clip nut for holding the injectors level.(The 0280155745 does take a clip nut and is otherwise identical to 0280155710 )
all stock XJ injectors use a clipnut

Why not FMS M9593-A302 255cc (24 lb)?

Too much flow for any stock 4.0L and old design, not as efficient as the newer EV6 Bosch injectors.

A better alternative is Neon 2.0L 95-96 injectors. They have a flow of 238cc (22.6 lb) @ 43psi, Part# 0280155703 (OEM# 5277739). ebay

These are EV6 4 hole injectors with clip nut. Better fuel economy, better throttle response, better power.
The disadvantage is that you'll need to take these out of two cars.
A list of vehicles that came with these injectors can be found here:

Another alternative are the 1999-00 Corvette LS1 injectors 0280155890,

They flow a bit less than the Neon injectors at 3 bar (22.5lb/hr) but will do just fine in any 4.0L. Some refer to these as 26.6lb/hr injectors but this is the flow at 4bar, at 39PSI/2.7bar they will flow 21 lb/hr

So why replace 248cc/min injectors with 238cc/min injectors? the EV6 injectors are capable of better atomization of the fuel hence less fuel is needed each stroke for the right A/F mixture.

If there is a need for more flow one can use the 96-98 Taurus/Sable 3l V6 DOHC injectors, 0280155715 256cc(24 lb ).

These are EV6 without clip nut and flow exactly the same at the FMS M9593-A302.

Another option would be the 2001-02 Camaro, 2001-04 Corvette LS1 injectors 0280155931

which flow a bit less but does have a clip nut. Both will out perform the older 24lb/hr EV1.3 FMS-M9593-A302 injectors.


99-01 Cherokee
These have a EV6/USCAR type injector electrical connector That is they are different from the earlier models.

Stock Jeep injector:
22.5lb/hr@49psi (236cc/min@337KPa)
or 21.14Lb/hr@43.5psi (222cc/min@300kpa)
Owners have used Ford 19# XF2E-C4B=204cc@43.5PSI injectors with success, they have the same specification as the #19 ford 280155710 (i.e. 4 hole ev6 style with a nominal working pressure of 39PSI) just with a UScar electrical connector and take clipnuts.

More flow (much closer to the stock injector flow rate than the ford XF2E-C4B) is provided by Bosch #0280155784 (22.5#=238cc@43.5psi), which are the same as the older Neon injectors 0280155703, but with a uscar electrical connector.

Chrysler part # 4669938 from;
DODGE CARAVAN (1998 - 2000)
DODGE NEON (1998 - 1999)
DODGE STRATUS (1998 - 2000)

Another alternative for the stock 99-up 4.0L is the (22.8#=240cc @ 43.5psi) Ford XR3Z 9F593 A4B / XR3E 9F593 A4B which is the newest design and offer even better performance.

(MOTORCRAFT #CM-4956,CM4956 XR3Z9F593AB, XR3Z-9F593-AB, XR3E9F593A4B, XR3E-9F593-A4B, YR3Z9F593AB, YR3Z-9F593-AB=all the same injector)
This injector has a single hole and looks disappointingly similar to the stock 99-'01 injector .
The main method for increasing atomization in the ev6 injectors was by increasing holes number and reducing each hole size. One can't add holes and reduce size indefinitely, so a new approach was needed when regulations became more strict.

The newer design is not relying on number of holes, it's a completely different approach with the difference in the internal orifice which allows far better atomization. This also gives an even better ability to work on variable pressure, as with most newer cars the pressure is computer controlled.
This, in turn, gives more accurate fuel mixture at any given pressure.

You can check the two in your fuel rail, when out, and compare the spray pattern, with the newer the fuel is like a mist.
Currently these can be bought near new for around $60 a set on ebay.

If even more flow is required the “1999 only” Taurus/Sable injectors, 0280155849 can be used.

This EV6 injector will flow 265cc/min @ 43.5 PSI, same as the FMS M9593-A302(24 lb) but with USCAR connector so the original injector clips on the loom will plug straight on..

Last, don't use lb/hr for rating injectors flow, as it always calculated from cc/min since injectors flow is Always measured using cc measuring tube. Some use 10.5 for calculating lb/hr, some use 10.4 and neither is correct.

I was thinking of upgrading my Injectors. The above is a result of the research I did, I hope someone finds it useful.

Handy links:
Most of the injectors mentioned above can be bought reconditioned for about $25 usd each, here:

Injector Pictures & flow rates:

Bosch injector specifications:

Cross referencing of part numbers:

Injector Electrical Connector Adapters — Bosch, Siemens Denso Fuel Injectors
EV6 to EV1 Adapters

91-95 Jeeps with Fuel Pressure Regulators (FPR) on the fuel rail.
Stock FPR Chrysler # 5303 0001 Supplies 31psi @ Idle and 39PSI at wide open throttle (WOT)

OBD1 upgrade Supplies 40psi @ Idle and 48PSI @ WOT Drops straight in, no modifications. Chrysler # 4418850 or 5277829 or 5277864 (Manufacturer: Delphi, Part#FP10046) ~$40USD on US ebay. (thanks to coas from cherokeeforum).

Drop in Adjustable FPR (he also does one for renix)

Adjustable FPR from hesco, requires the use of a file:

For the Ausi Wrecking yard Ferrets& Ebay bandits

AU ford Falcon 4.0L
Stock injector Bosch # 0280155844 have the exact same specifications as the (American ford 19#) 0280155710 but takes clip nuts.

Holden Commodore 3.8l V6
VT, VU, VX, VY, WH, WK and KIA Mentor and Shuma

Bosch #0280155777 Have a coil resistance of 12 ohms and a nominal working pressure of 49psi otherwise the flow rates @ 43.5psi are just a wee (insignificantly so) bit smaller and all other specifications are the same as the ford AU injectors.

It should be reiterated here that the #19 ford (and holden) injectors will drop straight in and work. However they do not really flow enough for use in a jeep 4L motor in '95 or earlier models that run 39PSI on the fuel rail at WOT. They may cause a lean condition at WOT and they will spend a lot of time working at grater than 80% duty cycle, this causes inefficient fuel atomization and a markedly shorter injector service life.
If you run a 48-49PSI fuel rail pressure you should be able to get a flow of 220cc which is the minimum of what is required.

If I had a post '96 (OBD2) I would verify I had 48-49PSI on the fuel rail, then I would go for the VT commodore injector, It has a lower impedance and Bosch state its nominal operating pressure is 350KPa/ 49PSI. Also, 3.8l VT Commodore makes 147kw @ 5200 RPM = 197 HP. Our jeeps make 190HP,
so the injectors can do it. And you can get cleaned & tested sets of 6 for ~ $120 on ebay.
Make no mistake, the beginning , middle & end of the "putting ford/ holden injectors in jeeps" argument is that they are common= cheap.
They are at the minimum side of what is ideal (but does work), so if you are porting heads, going with bigger valves and or playing with cams you may wish to fork out a little extra coin and go for 703/784 injectors mentioned above. Or even thease;

Injectors from a HSV VR, VS AND VT SERIES 1, 5.7L V8. Bosch #0 280 156 013 (they are bright orange) these flow at around 230cc@43.5psi, Which is much closer to the stock injector flow rates, have 12ohm resistance and a nominal working pressure of 49PSi. Your not realy likely to just stumble across these in a wrecking yard but it is an option, and you can get them new on ebay

TIP Sheet
If the above post made your eyes water and brain hurt (ie your normal) this tip sheet is a summery of research & thought process outlined above. Look up your XJ year, pick your injector.

Is my jeep OBD1 (39psi @W.O.T.) or OBD2 (49psi@W.O.T)?

How to: Injector replacement in a XJ,TJ&ZJ.

DIY Injector rebuild
Obd1 scanner.
'95 sport,4.6 stroker, 4.5" lift, 32"s, 4:10's, 8.25&SYE, taurus fan

Last edited by rainman; 01-06-2016 at 07:24 PM.

Sponsored Posts
Old 30-12-2009
rainman's Avatar
rainman  rainman is offline
Rock Munki
Join Date: Mar 2008
Location: Kellyville NSW
Posts: 2,265
What Jeep do I drive?: XJ
Likes: 140
Liked 280 Times in 167 Posts

The reason for going with new injectors are primarily that at wide open throttle it was running a bit lean(but not lean enough to ping), oxy voltage was .7-.75 volts whereas for max power I should be looking at .85-9 volts.
other reasons were that the injectors in there are 15years old and to get then cleaned was going to cost about $150, and if one still doesn't flow correctly after cleaning then it was going to be more than $200. and will more than likely still not get .85-9 volts @WOT.
Also there is the better fuel economy that is expected with the newer design of injector.

Mods on the engine are; late model intake, extractors, 21/2" straight through exhaust, 62mm throttle body, and airflow snorkel. 1995, OBD1.
Obd1 scanner.
'95 sport,4.6 stroker, 4.5" lift, 32"s, 4:10's, 8.25&SYE, taurus fan

Last edited by rainman; 28-01-2010 at 11:10 PM.
Old 26-01-2010
rainman's Avatar
rainman  rainman is offline
Rock Munki
Join Date: Mar 2008
Location: Kellyville NSW
Posts: 2,265
What Jeep do I drive?: XJ
Likes: 140
Liked 280 Times in 167 Posts

So I ordered the neon injectors, they were $200 Aud delivered.
They came with new o rings, and dropped straight in, clip nuts and electrical connectors went on no worries, took less than and hour to install.
I cleared the computer memory by touching the +ve battery terminal to the -ve for 10 seconds or so.
Turned the key to on to engage the fuel pump, on mine ('95 )it runs for about 3 seconds then turns off again, so I did it twice more to make sure the fuel rail was purged of air and to check for leaks on the new injectors.
Started first pop took it for a drive worked fine, no real noticeable difference other than it "seemed" Smoother.
To day will take it for a run and look at the AF ratio at wide open throttle, using the jeeps narrow band oxy sensor, as go jeep explains:

This is the test rig I use, Vacuum gauge and oxy sensor voltage output.

When I replaced the inlet manifold i tapped into the oxy voltage output wire and mounted a easily accessible plug on the inlet manifold to make testing less of a hassle.
it is the green wire with the blue heat shrink over a female spade electrical connector on the end.
Obd1 scanner.
'95 sport,4.6 stroker, 4.5" lift, 32"s, 4:10's, 8.25&SYE, taurus fan

Last edited by rainman; 26-01-2010 at 08:53 AM.
Old 26-01-2010
rainman's Avatar
rainman  rainman is offline
Rock Munki
Join Date: Mar 2008
Location: Kellyville NSW
Posts: 2,265
What Jeep do I drive?: XJ
Likes: 140
Liked 280 Times in 167 Posts

Well, with the new injectors it is .95 / .94 at 4000 rpm and WOT it was about .75 with the old injectors.

This afternoon I pulled the exhaust pipe and will weld in a oxy-sensor bung in front of the cat for a wide band setup tomorrow. See how the numbers from the wide band unit gell with the narrow band & voltmeter technique.

Fuel economy numbers will be taking a while
Obd1 scanner.
'95 sport,4.6 stroker, 4.5" lift, 32"s, 4:10's, 8.25&SYE, taurus fan

Last edited by rainman; 26-01-2010 at 09:56 PM.
Sponsored Posts
Old 28-01-2010
rainman's Avatar
rainman  rainman is offline
Rock Munki
Join Date: Mar 2008
Location: Kellyville NSW
Posts: 2,265
What Jeep do I drive?: XJ
Likes: 140
Liked 280 Times in 167 Posts

So with the wide band.
Warm idle AF=13.9
warm Cruse af=14.3
warm acceleration=14.3
warm WOT AF=11.3
Soooooo would seem that it is currently running a wee bit rich.
Thease WOT numbers also gell nicely with the narrow band &volt meter wide open throttle numbers.
Next I am going to check fuel rail pressure it should be 39psi, and the vehicle was stock as a rock when I got it so not really expecting any surprises there.

it has only been a few starts since the memory was reset so I think i Will do another run in a while to see if the other numbers change.

As for WOT as far as I see it my choices are:
1. Do nothing it is not a daily driver and you really do not spend much time at WOT
2. Some how get more air into the engine, I believe I have pretty much done all the easy/ economical stuff. next is porting the head, and that is not really ringing my bell.
3. adjust the map sensor voltage input down as described / explained by gojeep:

I am leaning to option 3 as the best way forward(have not really been thinking about it for that long though).

Ok anybody got some idears? see something I am missing?
Obd1 scanner.
'95 sport,4.6 stroker, 4.5" lift, 32"s, 4:10's, 8.25&SYE, taurus fan
Old 29-01-2010
rainman's Avatar
rainman  rainman is offline
Rock Munki
Join Date: Mar 2008
Location: Kellyville NSW
Posts: 2,265
What Jeep do I drive?: XJ
Likes: 140
Liked 280 Times in 167 Posts

Word from cherokeeforum is that I have to run it in and let the computer learn the new injectors for a least a while if not the whole 50 starts before I can determine what is going on.
So that is it for now.
Obd1 scanner.
'95 sport,4.6 stroker, 4.5" lift, 32"s, 4:10's, 8.25&SYE, taurus fan

Last edited by rainman; 03-02-2010 at 01:49 PM.
Sponsored Posts
Old 29-01-2010
BennyWA's Avatar
BennyWA  BennyWA is offline
Join Date: Oct 2005
Location: Swan Valley WA
Age: 40
Posts: 2,643
What Jeep do I drive?: None
Likes: 22
Liked 5 Times in 4 Posts

Sweet, good work- keep us posted!
Cheers, Ben
Old 30-01-2010
stroked's Avatar
stroked  stroked is offline
Sponsored by Centrelink
Join Date: Jan 2009
Location: NASA Space Station
Age: 14
Posts: 1,540
What Jeep do I drive?: TJ
Likes: 0
Liked 0 Times in 0 Posts

ill be running 24lbs injectors when its finised.
JKU 4",12" fox smoothies, sidebiters and some nitto's!
Post New Thread  Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

» Advertisements_AS2

Powered by vBadvanced CMPS v3.2.3

All times are GMT +10. The time now is 05:58 AM.

AJOR does not vouch for or warrant the accuracy, completeness or usefulness of any message, and are not responsible for the contents of any message. The messages express the views of the author of the message, not necessarily the views of AJOR or any entity associated with AJOR, nor should any advice be substituted as technical advice replacing that of a mechanic. You agree, through your use of this service, that you will not use AJOR to post any material which is knowingly false and/or defamatory, inaccurate, abusive, vulgar, hateful, harassing, obscene, profane, sexually oriented, threatening, invasive of a person's privacy, religious, political or otherwise violative of any law. You agree not to post any copyrighted material unless the copyright is owned by you or by AJOR. The owner, administrators and moderators of AJOR reserve the right to delete any message or members for any or no reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold harmless AJOR, the administrators, moderators, and their agents with respect to any claim based upon transmission of your message(s). The use of profile signatures to intentionally mislead or misdirect any member on this forum is not acceptable and may result in your account being suspended. Any trip that is organised through the AJOR forum is participated at your own risk. If you or your vehicle is damaged it is your responsibility, not that of the person that posted the thread, message or topic initiating the trip, nor the organisers of AJOR or moderators of any specific forum. This forum and associated website is the property of AJOR.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

AJOR © 2002 - 2018 AUSJEEPOFFROAD.COM. All corporate trademarked names and logos are property of their respective owners. Ausjeepoffroad is in no way associated with DaimlerChrysler Corporation or Fiat Jeep.
vB Ad Management by =RedTyger=