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Unread 03-28-2012, 09:02 AM   #136
augiedoggy
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Quote:
Originally Posted by zander21510 View Post
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
lol...were you kidding? According to your own data the 703 injectors are way overkill for the three engines in question...especially the 5.2 and 5.9....
the later stock 778 injector is good for up to 350hp.... its the better spray pattern we are after not more fuel..

again this is why the yellow 19-20lb injectors are often recommended on all the 94 and older setups.....


But your right the pcm totally controls them all differently based on their ohms class and the expected flow ratings that are plugged into the programming... this means the pcm is assuming its a specifice size injector and adjusts for that size until warmup when the 02 sensors come into play and actually enable it to attempt to adjust in real time with actual air/ fuel data...

its weird that Chrysler both increased the size of the injector as well as increased the pressure which increases flow at the same time when switching to OBD11 pcm systems... they must have discovered some benefit? maybe a more atomized spray pattern at higher pressure

And there must be huge differences in how the pcm controls those totally different injectors at a much higher pressure than it did in the earlier years.... Again the main reason I say its not a one size fits all application like suggested here.

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Unread 03-28-2012, 10:48 AM   #137
zander21510
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It just seems like if the 96-98 engines are running rich, then they all should be running rich. In fact the 93 thru 95s should be running way rich according to my numbers...but there have been people with 5.2s with success. In fact the Guy who did the writeup for the 5.2 on here did it to a 98....seems like the likely culprit to me would be a faulty injector or two.
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Unread 03-28-2012, 11:32 AM   #138
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It still seems to me that a good match for the 5.9 is the Bosch 703 injector... anyone disagree?
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Unread 03-28-2012, 11:44 AM   #139
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Quote:
Originally Posted by nickszj View Post
It still seems to me that a good match for the 5.9 is the Bosch 703 injector... anyone disagree?
I think so...there's no reason the 703s shouldn't work on every engine.
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Unread 03-28-2012, 04:05 PM   #140
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Originally Posted by zander21510 View Post
I think so...there's no reason the 703s shouldn't work on every engine.
except all the reasons I just stated LOL...go ahead and do it and report how much LESS fuel you use with WAY BIGGER injectors that are dumping MORE fuel.... I honestly didnt think this was a hard concept... not one place that sells injectors recommends a 22lb injector to replace the 19lb ones found in the older jeeps...there IS a reason.
a faulty injector or two would only foul the plugs for that cylinder... mine were all fouled out.... and I had liquid gas literally pouring out af an exhaust leak until I replaced the headers.... which didnt make it run any better...

notice this site states the 95 and older 5.2 and 5.9 needs the smaller injectors.

http://fuelinjectorconnection.com/sh...ewCat&catId=13
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Unread 03-28-2012, 04:08 PM   #141
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Quote:
Originally Posted by nickszj View Post
It still seems to me that a good match for the 5.9 is the Bosch 703 injector... anyone disagree?
It would only seem that way if you ignore the fact that the computer also controls the flow and the 95 and older 5.9's are setup for way smaller injectors...

But please do try them and tell me if my experience with them is a fluke...
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Unread 03-28-2012, 04:42 PM   #142
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if your experience can be reproduced, there has to be another factor besides the amount of fuel flow here.
the difference between the stock and 703 injectors flow at 49psi on 96-98 5.2s and the 98 5.9 is only .3 lb/hr more at 49psi, whereas people doing it with the 93-95 and who are as I understand having success with the 703s are flowing 3.1 lb/hr more than the stock 809s at 39psi.

Now i've read on other forums over my time posting on jeep forum that the 5.2 & 5.9 in the Dodge trucks are managed completely different from the ones in the Jeeps... completely different electronic and fuel management systems. This might play a role.

The guy who wrote the procedure for the 5.2/5.9 replaced the injectors on his 98 5.2 jeep with 703s and noted immediately positive results...so there has to be something different with either the dodge truck engine management systems or something went very wrong with your truck...

So everyone reading this...share your results regardless of engine size! Include model year, engine size and the injectors (703 or 715) you used, and your results. We can improve the thread and give more information to those thinking about doing this swap.
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Unread 03-28-2012, 04:49 PM   #143
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I just bought 8 new 703's for $200. So I will provide feedback as to how these worked on my 5.9 JGC. I will say that following Zander's reasoning, this should work... regardless of Augie's experience with his Dodge truck. A the very least, if this works for me, Augie will know its his truck that is the porblem, not the injectors or the rationale.
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Unread 03-28-2012, 05:30 PM   #144
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cool thats all I ask....
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Unread 03-28-2012, 05:54 PM   #145
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Quote:
Originally Posted by augiedoggy View Post
It would only seem that way if you ignore the fact that the computer also controls the flow and the 95 and older 5.9's are setup for way smaller injectors...

But please do try them and tell me if my experience with them is a fluke...
I'm going with fluke or differences in Dodge truck engine management. I have a 5.9L in my '94 using the '94 5.2L computer with the 703s and have nothing bad to say about them, much less anything like what happened in your truck. Injectors with 17% more flow (19lb -> 22.xlb) will not even flow that 17% extra except for high throttle due to the ramp-up and ramp-down period of each injector pulse; you're looking at, maybe, 10% more during open-loop operation, and at all other times (closed-loop) the computer will be directly managing pulse time via the O2 sensor. A mere 10% extra during open-loop cannot, by itself, cause an engine to run so incredibly rich as to eject unburned fuel.
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Unread 03-29-2012, 05:39 PM   #146
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Quote:
Originally Posted by augiedoggy View Post
It will run... will it run better or use less gas... NO just the opposite those 24lb injectors are way overkill for a 5.2 or a 5.9 without a cutom tune to trim back the fuel levels.
They will be dumping too much fuel until the truck goes closed loop and even then they will likely be spraying too much fuel...
You need to have your engine on a scanner or wideband meter while running these and you'll see exactly what I mean...
or run them and find out the hardway what kind of damage running rich can do... hell anyone whos running them now just pull your 02 sensor and look at it... I bet its sooty and black like the inside of your cat converter now vs tan in color...
EDIT I should clarify
If you are running the 24's in the older 5.9 jeeps with the 39psi they may be ok... the 93-95 dodge 5.9l used 24 lb injectors before they switched to 778 ones because of better flow at lower fuel pressures... however if you jeep had 778 injectors the pcm is likely setup for the 22lb injectors (flowing at 23.2lbs at 49psi)... the 93-95 5.2 l used smaller injectors and different leaner pcm tables... here is a flow chart..Jeep may have possibly changed this a bit I dont know.

Dodge Engine Years Flow rate in lb/hr
5.2 Magnum 92-95 18.2
5.2 Magnum 96-01 23.2
5.9 Magnum 93-95 24.5
5.9 Magnum 96-01 23.2
Ok, I'm confused, I'm running the 4.0 motor, but you referenced the V8's.....

lol
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Unread 03-29-2012, 05:45 PM   #147
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Quote:
Originally Posted by nickszj View Post
I just bought 8 new 703's for $200. So I will provide feedback as to how these worked on my 5.9 JGC. I will say that following Zander's reasoning, this should work... regardless of Augie's experience with his Dodge truck. A the very least, if this works for me, Augie will know its his truck that is the porblem, not the injectors or the rationale.
Cool, lookin forward to your results

Quote:
Originally Posted by V65Ozzie View Post
Ok, I'm confused, I'm running the 4.0 motor, but you referenced the V8's.....

lol
Look on the first page, I believe the 4.0 write up is perfectly fine but you are looking for the 703 injectors
Bosch 0280155703; 21.5lb/hr @ 39psi & 24.0lb/hr @ 49psi
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Unread 03-29-2012, 06:04 PM   #148
zander21510
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Quote:
Originally Posted by V65Ozzie

Ok, I'm confused, I'm running the 4.0 motor, but you referenced the V8's.....

lol
Yeah, remember everyone the original post has everything you need for the most part, the rest is discussion on how to improve the OP, specifically the v8 write up to see why some people have it working and others don't .
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Unread 03-29-2012, 11:35 PM   #149
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Zander, thanks for doin this write-up and for putting up w/ all these dweebs with their illiteracy and comparing jeeps to dodges to camrys. I dont know how your head doesnt hurt when you read some of these posts. Your a better man than me.
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Unread 03-30-2012, 07:22 AM   #150
V65Ozzie
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Originally Posted by AcidAnton View Post
Cool, lookin forward to your results


Look on the first page, I believe the 4.0 write up is perfectly fine but you are looking for the 703 injectors
Bosch 0280155703; 21.5lb/hr @ 39psi & 24.0lb/hr @ 49psi
Ok, back to the JY are some point........
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