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Thoughts?
I completely get that and was figuring the same thing... Originally Posted by HeyYou
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?
I wonder why its pulling fuel..
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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'm running bosch 703 injectors... they are 12ohm and black and flow 238cc at 3bar vs stock which is also 12ohms and flow 234cc at 3 bar....Originally Posted by drewactual
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..
it should be close as far as fuel flow.
Champion
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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.)
it absolutely does limit or add... it starts with a table hard scripted in the PCM.. the curve can be addressed there depending on sizes used.. that table can't be 'learned' by the engine.. it takes a 'tuner' to alter it.. Originally Posted by HeyYou
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.)
once the engine closes loop, it pulls o2 data and alters STFT to achieve and maintain close to stoich.. after a bit, the LTFT becomes sorta 'set', and the PCM refers to it when it closes loop, and deviates the STFT from the LTFT baseline..
all of that is 'learned', but the premise to get it all started is the scripted table.. if the injector is NOT providing the expected rate of flow due to whatever variable such as fuel pressure, obstruction, leak, ect.. or if the injector size is different, the PCM will compensate for it over time.. unless the difference is drastic.. then it will have a helluva time trying to match..
this was my issue- my injectors were the right size (unknown to me), and I had Sean curve 5% off of them.. my wide band said "good2go".. my STFT was crossing zero like it was cool- but the LTFT was way high- (it's said when it crosses somewhere between 20~25% either high or low and stays there a set amount of time, it will toss a code).. I never saw a code, but it was straight up dumping up to that line..
I put the canned '91' tune back on, and ran it.. the STFT is still crossing zero, the wide band is in the happy range at all throttles, and the LTFT is single digit (high, but I know why)..
I'll hush up about it now, because it is argumentive territory- but these engines need more flow rate than what was previously published here to run right.. or, at least, mine does.
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Probably because injector flow isn't always linear with pressure..... More like a curve as pressure increases.
Aren't the stockers rated at like 25 lb/hr at 43.5??
Aren't the stockers rated at like 25 lb/hr at 43.5??
HeyYou
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once the engine closes loop, it pulls o2 data and alters STFT to achieve and maintain close to stoich.. after a bit, the LTFT becomes sorta 'set', and the PCM refers to it when it closes loop, and deviates the STFT from the LTFT baseline..
all of that is 'learned', but the premise to get it all started is the scripted table.. if the injector is NOT providing the expected rate of flow due to whatever variable such as fuel pressure, obstruction, leak, ect.. or if the injector size is different, the PCM will compensate for it over time.. unless the difference is drastic.. then it will have a helluva time trying to match..
this was my issue- my injectors were the right size (unknown to me), and I had Sean curve 5% off of them.. my wide band said "good2go".. my STFT was crossing zero like it was cool- but the LTFT was way high- (it's said when it crosses somewhere between 20~25% either high or low and stays there a set amount of time, it will toss a code).. I never saw a code, but it was straight up dumping up to that line..
I put the canned '91' tune back on, and ran it.. the STFT is still crossing zero, the wide band is in the happy range at all throttles, and the LTFT is single digit (high, but I know why)..
I'll hush up about it now, because it is argumentive territory- but these engines need more flow rate than what was previously published here to run right.. or, at least, mine does.
Yours ain't exactly stock any more either. Originally Posted by drewactual
it absolutely does limit or add... it starts with a table hard scripted in the PCM.. the curve can be addressed there depending on sizes used.. that table can't be 'learned' by the engine.. it takes a 'tuner' to alter it.. once the engine closes loop, it pulls o2 data and alters STFT to achieve and maintain close to stoich.. after a bit, the LTFT becomes sorta 'set', and the PCM refers to it when it closes loop, and deviates the STFT from the LTFT baseline..
all of that is 'learned', but the premise to get it all started is the scripted table.. if the injector is NOT providing the expected rate of flow due to whatever variable such as fuel pressure, obstruction, leak, ect.. or if the injector size is different, the PCM will compensate for it over time.. unless the difference is drastic.. then it will have a helluva time trying to match..
this was my issue- my injectors were the right size (unknown to me), and I had Sean curve 5% off of them.. my wide band said "good2go".. my STFT was crossing zero like it was cool- but the LTFT was way high- (it's said when it crosses somewhere between 20~25% either high or low and stays there a set amount of time, it will toss a code).. I never saw a code, but it was straight up dumping up to that line..
I put the canned '91' tune back on, and ran it.. the STFT is still crossing zero, the wide band is in the happy range at all throttles, and the LTFT is single digit (high, but I know why)..
I'll hush up about it now, because it is argumentive territory- but these engines need more flow rate than what was previously published here to run right.. or, at least, mine does.
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Aren't the stockers rated at like 25 lb/hr at 43.5??
stockers are like 22lb at 43psi.... and closer to 24-25 at 49 psi If I remember correctly...Originally Posted by HeyYou
Probably because injector flow isn't always linear with pressure..... More like a curve as pressure increases. Aren't the stockers rated at like 25 lb/hr at 43.5??
ok here's what I dug up....from jeep forum....http://www.jeepforum.com/forum/f13/d...p-how-1305456/
Chrysler Injector: Bosch 0280155703 (22.67lbs/hr@43.5 PSI (12 OHM)) (what I have now) gen 3 disc 4 hole
Ford Injector: Bosch 0280155715 (24.38lbs/hr@43.5 PSI (14 OHM)) (these are usaully blue) gen 3 disc 4 hole
Stock Jeep (also dodge) Injector: Siemens 53030778 (22.28lbs/hr@43.5 PSI (12 OHM)) gen 2 1 pencil 1 hole
thats pretty damn close to stock as far as flow...
the red ones that fivo sells are actually...
Chrysler Injector: Bosch 0280155703 (22.67lbs/hr@43.5 PSI (12 OHM)) (what I have now) gen 3 disc 4 hole
Ford Injector: Bosch 0280155715 (24.38lbs/hr@43.5 PSI (14 OHM)) (these are usaully blue) gen 3 disc 4 hole
Stock Jeep (also dodge) Injector: Siemens 53030778 (22.28lbs/hr@43.5 PSI (12 OHM)) gen 2 1 pencil 1 hole
thats pretty damn close to stock as far as flow...
the red ones that fivo sells are actually...
- Bosch Fuel Injector 0280156013
- 24lb; 255cc/min at 43.5; psi 14 Ohms
- Ford, Jeep, Chevy, BMW, Dodge Trucks gen 3 disc 4 hole
- so they are much bigger than mine...
Champion
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Aren't the stockers rated at like 25 lb/hr at 43.5??
this is the confusion.. Originally Posted by HeyYou
Probably because injector flow isn't always linear with pressure..... More like a curve as pressure increases. Aren't the stockers rated at like 25 lb/hr at 43.5??
places like fiveO (and a host of others) publish straight up WRONG flow data.. it makes it HELL to try to figure out..
the 'red' injectors that came stock on my '02 5.9L were rated @ 248cc/min.. iirc.. that equates to 23.6# and hour of flow.. they are rated @ 43.5psi.. they are delivering somewhere in the range of 26# is my guess (guess was an assumed steady increase, which isn't actual- they can behave quite differently at differing pressure rates)..
the ones I replaced them with flow 252cc/min and are 24#/hr injectors.. but they are four hole, and atomize better..
I can't tell you with definitive solution about the delivery until the weather warms for a decent amount of time.. the computer is controlling the flow and maintaining stoich.. I won't know for certain until I get steady temperatures in the intake that are reasonably 'normal'.. I'm dumping a touch more fuel because of the cool intake..
the ONLY place this issue is evident is the LTFT.. the computer is controlling all other aspects, and making it transparent.. if it weren't for that long term figure, I wouldn't know.. understand, now, this wouldn't matter to most users- it is just a curiosity for me, because the computer CAN manage it.. my concern enters when I ask the question "if the PCM is already being taxed to maintain trim, what happens when I encounter a problem with the fuel system? if it is barely handling it now, it will certainly be an issue if something goes wrong"... I'm not worried about rich- that will be obvious, and not a big deal.. I'm worried about lean.. that won't be as obvious until I look in the rear view and see huge clouds of white smoke and hear a rock concert under the hood..
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places like fiveO (and a host of others) publish straight up WRONG flow data.. it makes it HELL to try to figure out..
the 'red' injectors that came stock on my '02 5.9L were rated @ 248cc/min.. iirc.. that equates to 23.6# and hour of flow.. they are rated @ 43.5psi.. they are delivering somewhere in the range of 26# is my guess (guess was an assumed steady increase, which isn't actual- they can behave quite differently at differing pressure rates)..
the ones I replaced them with flow 252cc/min and are 24#/hr injectors.. but they are four hole, and atomize better..
I can't tell you with definitive solution about the delivery until the weather warms for a decent amount of time.. the computer is controlling the flow and maintaining stoich.. I won't know for certain until I get steady temperatures in the intake that are reasonably 'normal'.. I'm dumping a touch more fuel because of the cool intake..
the ONLY place this issue is evident is the LTFT.. the computer is controlling all other aspects, and making it transparent.. if it weren't for that long term figure, I wouldn't know.. understand, now, this wouldn't matter to most users- it is just a curiosity for me, because the computer CAN manage it.. my concern enters when I ask the question "if the PCM is already being taxed to maintain trim, what happens when I encounter a problem with the fuel system? if it is barely handling it now, it will certainly be an issue if something goes wrong"... I'm not worried about rich- that will be obvious, and not a big deal.. I'm worried about lean.. that won't be as obvious until I look in the rear view and see huge clouds of white smoke and hear a rock concert under the hood..
see my post above...those red ones five o sells are actuall 255cc injectors...Originally Posted by drewactual
this is the confusion.. places like fiveO (and a host of others) publish straight up WRONG flow data.. it makes it HELL to try to figure out..
the 'red' injectors that came stock on my '02 5.9L were rated @ 248cc/min.. iirc.. that equates to 23.6# and hour of flow.. they are rated @ 43.5psi.. they are delivering somewhere in the range of 26# is my guess (guess was an assumed steady increase, which isn't actual- they can behave quite differently at differing pressure rates)..
the ones I replaced them with flow 252cc/min and are 24#/hr injectors.. but they are four hole, and atomize better..
I can't tell you with definitive solution about the delivery until the weather warms for a decent amount of time.. the computer is controlling the flow and maintaining stoich.. I won't know for certain until I get steady temperatures in the intake that are reasonably 'normal'.. I'm dumping a touch more fuel because of the cool intake..
the ONLY place this issue is evident is the LTFT.. the computer is controlling all other aspects, and making it transparent.. if it weren't for that long term figure, I wouldn't know.. understand, now, this wouldn't matter to most users- it is just a curiosity for me, because the computer CAN manage it.. my concern enters when I ask the question "if the PCM is already being taxed to maintain trim, what happens when I encounter a problem with the fuel system? if it is barely handling it now, it will certainly be an issue if something goes wrong"... I'm not worried about rich- that will be obvious, and not a big deal.. I'm worried about lean.. that won't be as obvious until I look in the rear view and see huge clouds of white smoke and hear a rock concert under the hood..
well after replacing my crank sensor and the cracked header I now have a truck that makes much less noise under the hood but is still misfiring... the #1 cylinder lining of the old header pipe was brown compared to black on the others so I fear the worse, Maybe bad lifter or cam lob?... At this point I'm going to throw my old timing gun on it to test for consistent spark...I have a used distributor coming because there a broken cap screw stud in my old one...maybe I'll get lucky and its the sensor in the distributor..
On a plus note I bought this header pipe liner spray from eastwood which is supposed to keep temps down... so far my headers havent changed color much... the truck is still running rich though (possibly from the cylinder not firing )
I only got one header replaced so far because of a stripped bolt on the other but the one I did change lined up perfect with the exhaust and fit with no issues..
On a plus note I bought this header pipe liner spray from eastwood which is supposed to keep temps down... so far my headers havent changed color much... the truck is still running rich though (possibly from the cylinder not firing )
I only got one header replaced so far because of a stripped bolt on the other but the one I did change lined up perfect with the exhaust and fit with no issues..