Things you should know about fuel Injectors and our trucks (Second time)
#11
09-28-2011, 03:27 PM
man, stock injectors are A-Okay.. the only time you'll benefit by upgrading is along with some major mods.. stick with them until proven otherwise.
Captain and me, man, we've shared more than a few PM's trying to hash out injectors- trying everything from swapping tunes to insights and opinions.. These things get confusing quick..
here is one: Ford Motor Sport (FSM) Injectors are mostly rated at 39psi of fuel pressure at the rail.. Meaning, pumping the somewhat industry standard 43.5psi will increase their rated delivery.. and the thing that can be MOST confusing about delivery at different psi is that characteristics of injectors are across the board too.. Think of it like this:
you have two injectors, both rated at what appears to be the emerging standard of 43.5psi.. one is a Bosch, the other is a Seimans.. You slap them on a machine producing 43.5psi and they both deliver as advertised.. and they both have nice little spray patterns.. then, you jack the pressure up, to say 49psi.. One of the two still has a decent spray pattern, but the other has resorted to a stream.. One is delivering what you would expect mathematically at 49psi as compared to 43.5psi, the other is not- it is producing more or less.. point being, the injectors are tested at the rated level to be capable of producing advertised delivery and pattern at that psi.. when you start messing around with either, you really don't know what you're going to get..
I too run FSM GenIII 24# injectors... I had to get Sean to curve back the duty cycle 6%.. I'm sure my PCM curved back some more all on it's own.. Based JUST on injector 'upgrade', there was zero gain (or loss for that matter).. I certainly wish I would have stayed with the factory injectors.. It would make life easier and more predictable.. speaking of predictable:
There is NO WAY, no matter how foul this sounds, that I would venture into experimenting with injectors, knowing now what I didn't know then.. I'll happily do something somebody else has done, (given that person was reliable and sensible).. there is just a lot more to it than there seems to be...
make life easier, not harder.. keep the stock injectors.. if you ever boost, or bore/stroke- THEN you're going to hafta make that change.. until then, you may want to leave it alone.
Captain and me, man, we've shared more than a few PM's trying to hash out injectors- trying everything from swapping tunes to insights and opinions.. These things get confusing quick..
here is one: Ford Motor Sport (FSM) Injectors are mostly rated at 39psi of fuel pressure at the rail.. Meaning, pumping the somewhat industry standard 43.5psi will increase their rated delivery.. and the thing that can be MOST confusing about delivery at different psi is that characteristics of injectors are across the board too.. Think of it like this:
you have two injectors, both rated at what appears to be the emerging standard of 43.5psi.. one is a Bosch, the other is a Seimans.. You slap them on a machine producing 43.5psi and they both deliver as advertised.. and they both have nice little spray patterns.. then, you jack the pressure up, to say 49psi.. One of the two still has a decent spray pattern, but the other has resorted to a stream.. One is delivering what you would expect mathematically at 49psi as compared to 43.5psi, the other is not- it is producing more or less.. point being, the injectors are tested at the rated level to be capable of producing advertised delivery and pattern at that psi.. when you start messing around with either, you really don't know what you're going to get..
I too run FSM GenIII 24# injectors... I had to get Sean to curve back the duty cycle 6%.. I'm sure my PCM curved back some more all on it's own.. Based JUST on injector 'upgrade', there was zero gain (or loss for that matter).. I certainly wish I would have stayed with the factory injectors.. It would make life easier and more predictable.. speaking of predictable:
There is NO WAY, no matter how foul this sounds, that I would venture into experimenting with injectors, knowing now what I didn't know then.. I'll happily do something somebody else has done, (given that person was reliable and sensible).. there is just a lot more to it than there seems to be...
make life easier, not harder.. keep the stock injectors.. if you ever boost, or bore/stroke- THEN you're going to hafta make that change.. until then, you may want to leave it alone.
I wonder if 24# injectors (really 25.5#) would be enough in a 4PSI boosted application? All we really need to do is get the remote turbo or a supercharger (And another tune, but the fuel would not need to be trimmed).
So you only need a 6% drop in duty cycle? I think it was 10% for me. He dropped my down 5% and it was still pinned rich (It still read 10.0 at WOT and that is how low the AF gauge goes)!!
#12
09-28-2011, 05:12 PM
#13
09-28-2011, 05:14 PM
Champion
I'm STILL rich at WOT.. like, pretty dang rich.. but at cruising speed, or under 2500rpm, (which I spend 99% of my time at) it is only slightly rich- like, around 12.4ish or so.. I could write Sean up and ask for a better tune to account for it, but it really isn't that far off to be worrying him about..
I've not changed tunes on my rig for some time, and haven't had cause to even pull the battery terminal.. I'm sure the PCM has altered the scripts enough to account for a good bit (within whatever parameters it can) of delivery, and if I foresee something about to happen to where I need to unhook the battery, I'll likely write him up and ask for a better tune..
right now, I have an exhaust leak anyway- at the floggin' header flange, and need to work that over before I get picky on tunes..
I've not changed tunes on my rig for some time, and haven't had cause to even pull the battery terminal.. I'm sure the PCM has altered the scripts enough to account for a good bit (within whatever parameters it can) of delivery, and if I foresee something about to happen to where I need to unhook the battery, I'll likely write him up and ask for a better tune..
right now, I have an exhaust leak anyway- at the floggin' header flange, and need to work that over before I get picky on tunes..
#14
09-28-2011, 08:15 PM
#15
09-28-2011, 08:40 PM
Champion
don't eff with my emotions smokey!! I'm part paranoid / part obsessed with that damn truck!! The division in parts is creating confusion with the shrink, and is the only reason I'm not officially diagnosed yet!!
I get around 12.5~13 mpg's.. not too bad considering 4.56:1, heavy **** QC third gen 4WD, and 35" sneakers.. I was, at one point getting better.. like, averaging just shy of fifteen.. I attributed that to flat lands and driving like a gramps.. the flat lands I can't change, but driving like gramps gets on my nerves..
in all seriousness, my figures may be jacked up in my noggin'.. I haven't had the wideband up and running in some time, and this exhaust leak wouldn't allow a good reading anyway (don't you know the header leaking is the floggin' one I tapped for the a/f gauge? gotta love luck..)
I ride the moto more often now, and limit the truck for short trips until I get the exhaust leak fixed.. but, you just tipped my obsessed/paranoid trigger, and may have just fast tracked my leak repair/af rehook/re-tune... hell, you may have just freaked me enough to order up some red OE replacements.. dang it..
I get around 12.5~13 mpg's.. not too bad considering 4.56:1, heavy **** QC third gen 4WD, and 35" sneakers.. I was, at one point getting better.. like, averaging just shy of fifteen.. I attributed that to flat lands and driving like a gramps.. the flat lands I can't change, but driving like gramps gets on my nerves..
in all seriousness, my figures may be jacked up in my noggin'.. I haven't had the wideband up and running in some time, and this exhaust leak wouldn't allow a good reading anyway (don't you know the header leaking is the floggin' one I tapped for the a/f gauge? gotta love luck..)
I ride the moto more often now, and limit the truck for short trips until I get the exhaust leak fixed.. but, you just tipped my obsessed/paranoid trigger, and may have just fast tracked my leak repair/af rehook/re-tune... hell, you may have just freaked me enough to order up some red OE replacements.. dang it..
#16
09-28-2011, 11:59 PM
Cruising I run 14-15. But after 3/4 throttle I get into the 13s and it is a STEEP dropoff. At wot I will be anywhere from 11.5-12.3.
I would have hemifever trim some more fuel for ya. I told him to trim more below 3/4 throttle. And I told him to trim as much as he thought was safe after 3/4 throttle.
On the HWY at 65-70 MPH, I get between 15 and 16 MPG. City I get about 11-12 MPG.
I would have hemifever trim some more fuel for ya. I told him to trim more below 3/4 throttle. And I told him to trim as much as he thought was safe after 3/4 throttle.
On the HWY at 65-70 MPH, I get between 15 and 16 MPG. City I get about 11-12 MPG.