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Do I need more Injector/Fuel pump

Discussion in 'Modified 1995-2001 Explorers' started by Notpretty, May 16, 2012.

^^Searches ExplorerForum.com^^





  1. ExDude

    ExDude B

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    Last edited: July 6, 2012
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  3. Notpretty

    Notpretty New Member

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    Lots of feedback that...has me unsure what to do.

    I crawl at 1200-1500 rpm 90% of the time but in snow or mud I will push the motor as far as I can...6000 +. Yes the cam limit of 5200 is a compromise between torque and a true high rpm motor...which mine is mostly not. But I have gearing in the transfer case (atlas 4.3:1) and diffs (5.13:1) and granny gear trans (6.69:1). Total crawl ratio over 150:1. This is where most of my torque comes from. So I sacrafice some motor low end with this cam but not all. Gain some high end but do not forget that most of the time I'm at 1200 rpm. It is truly a dual purpose motor. Trust me...when I dump the throttle it will be no less than as if doing a quarter mile....and snow slips allowing even higher rpm. I'll rev limit the motor for safety.

    So based on fly wheel HP...my HP at ground given the drivetrain...trans/tranny/tcase and 40 inch tires would be extremely hard to predict...I'm still...I think...sitting at the 300 to 325 HP area. Simple question. Should I fear leaning out with 19# injectors if I set the rev limit at 6k?

    Great info guys. Thanks. Very confusing though.
     
    Last edited: May 19, 2012
  4. Notpretty

    Notpretty New Member

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    Okay...I hear you, but do you think the mod's I've made to the motor...Heads/Cam/Headers/Roller rockers... are enough to push the 19# injectors. In your above example you are talking "typical Mustang" and I want to know if you are taking into account my mods and how they affect my set up and thus needs for fuel pump/injectors. Also...is the stock fuel pump enough? General question about how EFI works...When the motor reads lean which is done I assume based on O2 sensor feedback what does it do to increase fuel? Does the computer hold the injectors open longer? Does it increase fuel pressure and if so how...how does it get more fuel into the motor? Again...no expert here. Trying to learn.
     
  5. RangerSVT

    RangerSVT Active Member

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    Fuel pressure (ie delivery to the motor/injectors) is automatic VIA vacuum. With a lot of vacuum (ie no load on the motor like in idle condition) there is plenty of vacuum, so when the fpr sees this vacuum it opens releasing fuel pressure. When there is a load such as full throttle, there is little to no vacuum, so the fpr closes allowing more fuel pressure to build...injector pulse is controlled via readings from the maf and tps, basically, how much throttle is being applied and how much air is entering the motor...

    SVT
     
    Last edited: May 20, 2012
  6. Notpretty

    Notpretty New Member

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    Completely lost. Fpr gps...? I litterally have no idea what you said.

    Edit

    Wait...fuel pressure regulator. So the O2 sensor which reads the results of combustion has nothing to do with fuel delivery? Still don't know what gps is.
     
  7. FIND

    FIND Well-Known Member

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    I think that was a typo, he meant to type TPS, throttle position sensor. FPR means fuel pressure regulator.

    edit:

    O2 sensors do also have something to do with fuel delivery. The fuel maps are basically tables that are based on throttle position and RPM. MAF readings and O2 sensor readings basically just shift things around a little bit.
     
    Last edited: May 19, 2012
  8. ExDude

    ExDude B

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    Last edited: July 6, 2012
  9. RangerSVT

    RangerSVT Active Member

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    Sorry, it is tps, not gps (damn auto-correction)...

    SVT
     

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