I took it as we were classed in the high impedance area; somewhere I was sure I read it was 14.5ohm’s

Edit: I think you would be fine using the Accel 23lbs

drewactual is much better suited to discuss the ohm than I am.

These were the injectors in my truck so I worked from here.*

So as you can see the Accel 23lbs do flow more than the stock Seimens injectors.

.................................................. Lbs.... cc/min .......Psi

Seimens/Chrysler P/N 53030778.......23.2...232 cc/min..49psi for 96-01 5.9l OBD2 *
.........................Accel 150123......23.....256 cc/min...49psi
.........................Accel 150124 .....24....267 cc/min....49psi currant

 

So if someone has a MTG 2500, how would one go about checking/setting fuel sync? I have the HUGE manual that covers "domestic vehicles" (assuming it includes Mexican Rams) but have not found this detailed there. Not that I need it know, but just wanting to know in the event......

 

I've reached the limit of my knowledge.. I simply took my truck and handed it over to the tech who set the sync for me.. He knew exactly what I was talking about before I even finished my first question- and verbally laid out the procedure as I had read it.. So, I don't know other than it took a scan-tool with proper keys.. I don't even know if that particular one was a snap on or not..

 

according to the research cmckenna did and mentioned in the thread I linked earlier 96-99 trucks used 12ohm injectors and anthing plus or minus 1.5ohm outside of than could screw with how the pcm controls it... I dont know though because a lot of people seem to be using 14-16 ohm ones on these engines from what I've read...of course according to my research on the matter most are also running pig rich and dont know it too...
five-O states below they are 14.5 ohms stock but he also has lots of incorrect info posted too so..
http://www.fiveomotorsport.com/product-search/?v=11788

this jeep forum correctly states they are 12ohm...again I tested mine with my fluke multimeter and get 11.7 ohms...
http://www.jeepforum.com/forum/f13/d...p-how-1305456/
also this confirms it http://www.witchhunter.com/flowdatapix/s53030778.jpg

and here is a great comparision video of the stock injestors used in our ram vs the bosch 4 hole units.... the stock injector looks like a squirt gun stream... funny that a little 4.0 straight 6 jeep used the same size injector as the 5.9 liter...
http://www.youtube.com/watch?v=41w3s...layer_embedded
based upon all this I'd say those "703" injectors from the jeepforum would be the ideal replacement units from stock....They also cover the same topics like ohm differences and pcms ability to compensate....

 

Five -0 sold me a set of Bosch '915' pink tops which they had rated at 26lbs at 43 for my 408 stroker. Which just about fried my motor at first start up. Way lean. Because, oops 95's only have 39 psi fuel pressure. So they were a perfect injector for stock replacement 5.9's (they would be about 24.5lbs at 39psi) So we put a 96 regulater on top of pump (49psi) and pushed them to about 27.5lbs.
No dynos around here so we were tuning using spark plug color and colder plugs as 408 is 10.5 compression. Still running a tad lean so we got some 30lb Accels and are running them at 49lbs for an injector rating of something like 31.4. Engine has been running with this combo for just about 16,000 klms with no issues.
So what I am getting to is ...I believe you can tune by using different pressures. In our case we just pushed more fuel into the pulse cycle tune. According to B&G...The ECU has the ability to add or subtract up to 30% of fuel. This from the land of OBD1.

 

I wonder if this is why my truck goes to -33.6 on the short and long fuel trim once warmed up...I am not running it this way since If I understand correctly its leaning out the mix right? it was smoking too like it was running too rich stops doing that once its warmed up... however my iac starts to open and I get the air pressure noise under the hood now when idling when hot?...
all this and I still have the missfire...however all the smoking has pointed out what appears to be a cracked header on the inside of the collector area...
I have the bosch 703 injectors which many are using on the 5.2 and 5.9 as well as the 4.0 engines on the jeep forums and they say they work great so not sure what different about my truck...I know I want to change the fuel retarding but I seen no mention of it in the jeep forums?

 

According to theory..... Retarding your injector timing with the four hole injectors really isn't such a bad idea. The stock fellers shoot a pencil stream of gas at the back of the toasty warm intake valve, and let the valve vaporize the fuel... not necessary with the four holers..... retarding your injector timing so the fuel event occurs while the valve is at least partially open, thus, air is moving fairly quickly.... seems like it would prompt more fuel to make it into the chamber, as opposed to having a chance to condense out of the non-moving air behind a closed valve.

Thoughts?

 

it's PULLING fuel if the number is negative.. this was part of my lesson of the last month:

the PCM doesn't report it's status, it reports what it's doing.. another way to say it: the PCM tells you what it's currently doing as opposed to providing information about current conditions..

 

with FMS GenIII four hole injectors:
my fuel sync is retarded 4%.. the response from the engine was undeniable..

I could NOT figure out why my LTFT was running high.. it was because I had my numbers on flow rates jacked up.. I keep saying this over and over, but: those red injectors deliver 23.6#@43.5psi.. that puts me near 26# at 49psi.. the engine is happy, the LTFT's are single digit (still high, engine is still dumping), and the mileage is marginally up.. The excess dump is because of silly low intake temperatures.. we're talking around 35* on an engine running 18~183*..

there HAS TO BE considerable margin (higher than previously thought) for the PCM to manage delivery.. the 30% sounds reasonable, and is much greater than my previous belief that it was between 8~10% on either side of the scripted delivery (what the engine will pump based on mechanics and no intervention by the PCM).. that 10% difference is big, if we're talking 15% on either side of rated delivery, and absolutely huge if we're talking 30% on either side..


edited to add:

my engine was managing the a/f... it was evident with the o2's STFT, and it was evident with the wide band.. the only discrepancy was the LTFT- which was upper teens.. the PCM was managing the weaker pulse rate to produce stoich 14.7ish.. the ONLY indicator something was amiss was the LTFT..

the LTFT are in order now.. I'm seeing anywhere from +5%~+9%.. I doubt I see that in the summertime.. I may even see the PCM curve on the LTFT to single digit low %..

another thing I learned: STFT is expressed in percentages deviated FROM LTFT.. in other words, if LTFT is +10%, and STFT is -2%, the duty cycle is +8%.. (it doesn't exactly work that way in math, but that is the premise)..

if you're running anything less than 21# injectors at 49psi, and on a OBDII engine, I think you're pushing the envelope..

 

I am not entirely sure the PCM is limited on how much it can correct fuel trim, or, if it is restricted at all.... I think it would be more a product of the flow rate of the injector..... is the injector able to deliver the correct amount of fuel at idle with a minimum pulse, and is it able to delivery enough fuel at high RPM, without going to 100% duty cycle......

Running to large of an injector will cause the engine to run rich at idle/low RPM, due to the high flow rate injecting too much fuel even with minimum pulse. Too small an injector will cause you to lean out at high RPM, if the injector isn't capable of putting out enough fuel, even at 100% duty cycle. (always open.)