What fuel pressure should I be running?
06-07-2006, 07:31 PM
#1
6th Gear Member
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Join Date: Feb 2005
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Posts: 8,439
What fuel pressure should I be running?
What fuel pressure should I be running with the mods listed in my signature? Man I've been whoring the 5.0 section today! Also, what do you guys think about Holley FPR's? I've got one on order.
06-07-2006, 08:00 PM
#2
2nd Gear Member
Join Date: May 2006
Location: Dallas
Posts: 329
RE: What fuel pressure should I be running?
ORIGINAL: 92hatchLX
What fuel pressure should I be running with the mods listed in my signature? Man I've been whoring the 5.0 section today! Also, what do you guys think about Holley FPR's? I've got one on order.
What fuel pressure should I be running with the mods listed in my signature? Man I've been whoring the 5.0 section today! Also, what do you guys think about Holley FPR's? I've got one on order.
also, adjusting fuel pressure does nothing except adjust the pulsewidth of the injectors. the ecm will always run the same air/fuel ratio regardless of where you set fuel pressure. basically, afpr is a worthless mod without a tweecer or something similar. here is a thread that explains why: look at post that starts - Mythology Case #4:
Increasing fuel pressure will raise HP http://www.my5oh.com/forum/viewtopic.php?t=70
06-07-2006, 08:28 PM
#3
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Join Date: May 2004
Location: las vegas, nv
Posts: 9,092
RE: What fuel pressure should I be running?
adjusting the fuel presure does not effect pulse width. the pulse width is the same, the amount of fuel that goes through while the injector is open is what changes.
you can adjust fuel pressure but it effects all rpms while under wot. so say your afr is perfect till 4000rpms and then it leans out. if you give it more pressure, your going to now run rich before 4000rpms. and once you get a tweecer or some other eec tuner, the afpr becomes completely worthless cause you can do all your afr adjustments with the tuner. just set it to 42 and leave it. if the car doesnt run right after that, adjusting fuel pressure wont fix it
you can adjust fuel pressure but it effects all rpms while under wot. so say your afr is perfect till 4000rpms and then it leans out. if you give it more pressure, your going to now run rich before 4000rpms. and once you get a tweecer or some other eec tuner, the afpr becomes completely worthless cause you can do all your afr adjustments with the tuner. just set it to 42 and leave it. if the car doesnt run right after that, adjusting fuel pressure wont fix it
06-07-2006, 08:36 PM
#4
2nd Gear Member
Join Date: May 2006
Location: Dallas
Posts: 329
RE: What fuel pressure should I be running?
ORIGINAL: luckythirteen13
adjusting the fuel presure does not effect pulse width. the pulse width is the same, the amount of fuel that goes through while the injector is open is what changes.
you can adjust fuel pressure but it effects all rpms while under wot. so say your afr is perfect till 4000rpms and then it leans out. if you give it more pressure, your going to now run rich before 4000rpms. and once you get a tweecer or some other eec tuner, the afpr becomes completely worthless cause you can do all your afr adjustments with the tuner. just set it to 42 and leave it. if the car doesnt run right after that, adjusting fuel pressure wont fix it
adjusting the fuel presure does not effect pulse width. the pulse width is the same, the amount of fuel that goes through while the injector is open is what changes.
you can adjust fuel pressure but it effects all rpms while under wot. so say your afr is perfect till 4000rpms and then it leans out. if you give it more pressure, your going to now run rich before 4000rpms. and once you get a tweecer or some other eec tuner, the afpr becomes completely worthless cause you can do all your afr adjustments with the tuner. just set it to 42 and leave it. if the car doesnt run right after that, adjusting fuel pressure wont fix it
06-07-2006, 08:41 PM
#5
2nd Gear Member
Join Date: May 2006
Location: Dallas
Posts: 329
RE: What fuel pressure should I be running?
briefly: if you raise fuel pressure, the engine will run rich...until the o2s read the rich condition, then the computer will shorten the pulsewidth to adjust back to a stoich state(14.64 a/f ratio)
if you lower fuel pressure the o2s will read this lean condition and the ecm will lengthen the injector pulsewidth to compensate.
the ecm can compensate for up to 25% + or - fuel pressure.
http://fordfuelinjection.com/files/GUFB.pdf this pdf is the single most important document for understanding how eec-iv works
if you lower fuel pressure the o2s will read this lean condition and the ecm will lengthen the injector pulsewidth to compensate.
the ecm can compensate for up to 25% + or - fuel pressure.
http://fordfuelinjection.com/files/GUFB.pdf this pdf is the single most important document for understanding how eec-iv works
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