The Definitive Injector Swap HOW TO - Page 9 - JeepForum.com
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post #121 of 675 Old 03-26-2012, 09:17 PM
augiedoggy
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Quote:
Originally Posted by zander21510 View Post
All of them were rated at 43.5, I converted them according to the stock fuel pressures I found
But some the numbers you quoted were at the wrong pressure like the 715's... reread what you posted and what it is after I corrected it. same with the 95 year injectors... the flow rates and conversions I found basically give the flow number you gave but at 43.5psi instead of the 39psi you stated...
go back and read my post I was editing when you quoted it...

I may be wrong on the 24.6 95 injectors I cant find them in my flow charts... and the numbers correspond with the flow rates I posted earlier today...even the 18.2lbs for the 93-94 5.2 models...
But that just goes to show the default open loop fuel tables are all over the place for different years and this can cause issues in some combinations..


Last edited by augiedoggy; 03-26-2012 at 09:30 PM.
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post #122 of 675 Old 03-26-2012, 10:51 PM Thread Starter
zander21510
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Quote:
Originally Posted by augiedoggy

But some the numbers you quoted were at the wrong pressure like the 715's... reread what you posted and what it is after I corrected it. same with the 95 year injectors... the flow rates and conversions I found basically give the flow number you gave but at 43.5psi instead of the 39psi you stated...
go back and read my post I was editing when you quoted it...

I may be wrong on the 24.6 95 injectors I cant find them in my flow charts... and the numbers correspond with the flow rates I posted earlier today...even the 18.2lbs for the 93-94 5.2 models...
But that just goes to show the default open loop fuel tables are all over the place for different years and this can cause issues in some combinations..
Perhaps you were confused by my bolding, meant to hi light all the pressures not just a few. Or I did copy them wrong...I tried to take the pressures and flow rates from witchunter, where they were all rated at 43.5psi. Using that I calculated the flow rates for 39 and 49 psi, I meant to list only those flow rates and not any 43.5psi ratings to give the projected flow rates on all model ZJs. Now i did guess on the 4.0... I assumed they were running pressures identical to the v8 of the same year. I'll double check tomorrow I suppose and put all the right numbers in the OP...thanks for the catch!

Damn things lol why does it have to be so confusing...
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post #123 of 675 Old 03-27-2012, 08:27 AM
nickszj
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Zander, with your flow numbers... will the FMS 19lb injectors be enough at 49psi for the 5.9?

1998 ZJ 5.9 limited in white. M1 intake and $20k+ mods brewing up in my head... SOLD

Looking for the right WJ to build into an expedition rig....
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post #124 of 675 Old 03-27-2012, 02:12 PM
augiedoggy
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Originally Posted by nickszj View Post
Zander, with your flow numbers... will the FMS 19lb injectors be enough at 49psi for the 5.9?
depends on which FMS 19lb ones you mean but the "700" ones will flow at 20.69lbs @ 49psi according to the calculator and witchhunters charts which is what Zander is using for reference too.... that means it should run very lean until it warms up enough to go into closed loop mode and the pcm can adjust flow... since the pcm is tuned for a 23.2lb flowing injector on the 96+ years
I know your looking for other opinions too but my calculations say that injector is too small..especially for your other mods like theM1 intake which sucks more air and fuel.... but dont take our words for it look for yourself...
http://www.witchhunter.com/flowdatapix/b0280155700.jpg

http://www.witchhunter.com/injectordata1.php4

http://www.csgnetwork.com/fiflowcalc.html
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post #125 of 675 Old 03-27-2012, 02:31 PM Thread Starter
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Shoot...I realize I used the converter with lbs instead of CC...

I'll rework the numbers...hold please
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post #126 of 675 Old 03-27-2012, 02:57 PM
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Augie... the M1 wont affect the injection selection one bit...

It's not that I am looking for other opinions... I am looking for the right answer as to which 4 hole injector we can use on the Jeep 5.9 engine. Its as simple as that for me...

To your credit, you have done a bunch of research, but you dont have it figured out either, at least for your Dodge... I am starting to think the Jeeps might be little different.

Hopefully, Zander can give some good feedback after working the numbers again..

1998 ZJ 5.9 limited in white. M1 intake and $20k+ mods brewing up in my head... SOLD

Looking for the right WJ to build into an expedition rig....
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post #127 of 675 Old 03-27-2012, 03:00 PM
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If I am reading Witchhunter's specs correctly... the 703's would be the best replacement for the 5.9 becuae they flow approximately the same rate, 234 to 238 cc at 3 bar adn 12 ohms.

1998 ZJ 5.9 limited in white. M1 intake and $20k+ mods brewing up in my head... SOLD

Looking for the right WJ to build into an expedition rig....
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post #128 of 675 Old 03-27-2012, 03:06 PM
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Quote:
Originally Posted by nickszj View Post
If I am reading Witchhunter's specs correctly... the 703's would be the best replacement for the 5.9 becuae they flow approximately the same rate, 234 to 238 cc at 3 bar adn 12 ohms.
Yes. 703s flow closest to stock and thus are an excellent choice for stock 5.9s. The only reason to go larger is if you have enough engine modifications to flow proportionally more air. A simple intake/exhaust upgrade will not exceed the limits of the 703s.

1994 5.9L ZJ, retrofitted UC package, NP242 swap, 17" JK Moabs with 32" BFG MT KM's.
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post #129 of 675 Old 03-27-2012, 03:09 PM Thread Starter
zander21510
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I have updated the OP with all injector flows at stock PSIs for comparison. I double checked the numbers and made sure the conversions were accurate, hope this will help solve the mystery of what to use!
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post #130 of 675 Old 03-27-2012, 03:14 PM
nickszj
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OK!!! Now we got somewhere... now the last question, for me at least... a reputable place to get a set of 703 injectors? I dont want to go JY hunting, would rather have them delivered all flow matched and all ready to install!

1998 ZJ 5.9 limited in white. M1 intake and $20k+ mods brewing up in my head... SOLD

Looking for the right WJ to build into an expedition rig....
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post #131 of 675 Old 03-27-2012, 08:55 PM
augiedoggy
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Originally Posted by nickszj View Post
If I am reading Witchhunter's specs correctly... the 703's would be the best replacement for the 5.9 becuae they flow approximately the same rate, 234 to 238 cc at 3 bar adn 12 ohms.
Yup that was stated in the first page and is why I bought the 703's ...But they would not work in mine.... maybe they were all defective and thats why they fouled my plugs out and dumped a quart of gas into my oil?...
The thing is if they work great at 39psi in the older 5.2 and 5.9's were much larger 24lb injectors were originally used than how could they work great in the newer ones at much higher 49psi and higher flow rate too? I mean even Chrysler used the different sized injectors and pressures for those injectors for a reason right? They have to be either running too lean or rich in open loop mode on one of the year groups. since the pcm doesnt use the air to fuel adjustments until then.
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post #132 of 675 Old 03-27-2012, 10:33 PM Thread Starter
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it almost looks as if the flow rating isn't the problem...because there seems to be no correlation with the flow numbers and the failed swaps.

I did some more calculations, specifically the required size injector for a certain horsepower at the flywheel at 80% duty cycle...it gives you the required CC/min rating of the injector needed.

Keep in mind the rating for the 703 is 24 lb/hr; and the 715 is 25.9 lb/hr


The 4.0 at 190hp calculated to 18.6 lb/hr, well under the ratings for the 703 and 715.
The 5.2 at 220hp calculated to 16.2 lb/hr, even more underneath the 703 and 715 ratings.
The 5.9 at 245hp calculated to 18.0 lb/hr, close to the 4.0.

Now, looking at the 96-98 models with these calculated minimum injector sizes, the stock 778 injector flows at 23.7 lb/hr and is equipped stock on all these engines for 96-98 with a pressure of 49psi...

I can't seem to figure out why the 96-98 5.2s would run so rich...none of the numbers show any reason the injectors should run so rich.

There has to be something in the fuel pump or the computer that makes it do this :P
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post #133 of 675 Old 03-27-2012, 11:19 PM
nickszj
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Quote:
Originally Posted by augiedoggy View Post
Yup that was stated in the first page and is why I bought the 703's ...But they would not work in mine.... maybe they were all defective and thats why they fouled my plugs out and dumped a quart of gas into my oil?...
The thing is if they work great at 39psi in the older 5.2 and 5.9's were much larger 24lb injectors were originally used than how could they work great in the newer ones at much higher 49psi and higher flow rate too? I mean even Chrysler used the different sized injectors and pressures for those injectors for a reason right? They have to be either running too lean or rich in open loop mode on one of the year groups. since the pcm doesnt use the air to fuel adjustments until then.
Now I see the problem.... Augie, you think the jeep 5.9 uses 24lbs injectors... They dont... At least not at 3 bar... They are more like 19s at 3 bar. At 49psi, they flow at 23.7. Zander shows that the 703s flow 24lbs at 49 psi which is just about right, the plus is a 4 hole injector.

1998 ZJ 5.9 limited in white. M1 intake and $20k+ mods brewing up in my head... SOLD

Looking for the right WJ to build into an expedition rig....
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post #134 of 675 Old 03-28-2012, 06:46 AM
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Originally Posted by nickszj View Post
Now I see the problem.... Augie, you think the jeep 5.9 uses 24lbs injectors... They dont... At least not at 3 bar... They are more like 19s at 3 bar. At 49psi, they flow at 23.7. Zander shows that the 703s flow 24lbs at 49 psi which is just about right, the plus is a 4 hole injector.
The 93-95 5.9liters flow is in question (the 809 injectors flow 19.5lbs at 43.5 psi according to my data ) .... the 96 up used the 22lb 778 injectors..and the 93-95 5.2 used 18lb injectors . Thats my point dodge used three different sizes on injectors on the 5.2 and 5.9 along along with different pressures to make them flow differently depending on application during different years

... and people here are saying they can all be replaced by the same injector without changing anything else like pressure or the fuel tables designed for the stock sized injectors... it simply wont work right that way.... some of they applications will either be too rich or too lean. period

the vehicles computer is tuned for a certian amount of flow at a certian pressure... you change that and it will be whacked out during the warmup period until its fixed... the computer doesnt paty attantion to the 02 sensors or start adjusting the fuel flow at all until its reached the warmup temp which is somewhere around 170 degrees...then it starts to attempt to either add or trim back fuel to get the right air/fuel ratio (if the injector is close enough in size to what it can adjust).... each time you start the engine when its cold it goes through this process over and over....

when I ran the 703 injectors the computer set the fuel trim at -33.6 once it warmed up enough to start to try to reduce the fuel.... thats as far as it can go... when this happened it smoked much less but still ran super rich and smoked when you fluttered the pedal... the fuel trims would then get a bit better until itwent back to idle then it would start to flood out again and go back to -33.6 telling me the computer couldnt lean out the mixture anymore... yes I reset the pcm before all this and drove it at 50 mph to try to get the pcm to relearn and adjust and yes everything works great now that the 778 injectors have been reinstalled...

So I am stumped and would like someone else who actually has a 96+ 5.2 or 5.9 that uses the higher 49psi fuel pump to try the 703 injectors and report back after they drive it that way for an hour or so and check thier oil and plugs....

and a better flowing exhaust and intake does improve the amount a air the engine can pump (as well as more fuel to go with that air)...not as much as they would with higher flowing heads but enough to be more than the difference between the stock 5.2 and 5.9... just saying the M1 would utilize bigger injectors better if anything....

Last edited by augiedoggy; 03-28-2012 at 06:59 AM.
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post #135 of 675 Old 03-28-2012, 07:11 AM
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Originally Posted by nickszj View Post
Now I see the problem.... Augie, you think the jeep 5.9 uses 24lbs injectors... They dont... At least not at 3 bar... They are more like 19s at 3 bar. At 49psi, they flow at 23.7. Zander shows that the 703s flow 24lbs at 49 psi which is just about right, the plus is a 4 hole injector.
the 703'2 flow at 24.1lb at 49 psi. Stock 778 injectors flowed at 23.67at 49 psi
do you see the increase? at higher pressures than the injector is rated for the flow curve becomes unpredicatable
those ame 703 injectors only flow 21.5 in the older 95 and older models with 39psi, about 3psi more than the 18.2lbs the 5.2 (and 5.9?) flowed with stock injectors... I believe they behave differently at different pressures and the flow isnt always linear to the pressure..(Plus the pcm effects flow by changing the on off strobe timing to add or remove fuel this is why the 5.2 pcm will make a 5.9 run lean if used to control one). ... the pcm can adjust flow better at lower pressure it seems but I bet those 95 and older 5.2's (and 5.9's) with 703 injectors are still running very rich. especially on warmup....

I know the 19.5lb "710" injectors are whats sold for the 95 and older 5.2 and 5.9 liters on almost every site that rebuilds them and sells them as an ungrade... and it should make sense that the 703's would be the closest replacement fro the 96+ model years 5.2 and 5.9 liters but again I tried them and had bad results...
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