Bigger Injectors

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Dec 13, 2005 | 01:15 PM

#31

Jefftopgun

Mountain Pass

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Im not quite sure, and I am a bit rushed, but I think I read somewhere that if an injector gets too hot, from an outside source, it can seize up and stop working. This is another reason ford opted for smaller higher pressure ijectors because those smog pipes or whatever that pump air into the head, and the exhaust are all on the same side. So on a hot day at idle, an injector could seize up causeing a bit of a problem.

Now I have a question, If you do a fair amount of upgrades, will it be possible to just replace the injectors with slightly larger ones, and have the computer not realize it because everything "lines up" so to speak. Like if your motor performs on the same fuel curve as the stock motor did with the stock injectors, or is gonna be almost impossible to get things to line up like that?

Thanks

Dec 13, 2005 | 01:22 PM

#32

optikal illushun

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From: Coal Region

from what i understand the computer will pull fuel out anyway.

i know what ur saying but the ECM doesnt think like we do...

Dec 13, 2005 | 02:26 PM

#33

Motorhead351

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....................

Last edited by Motorhead351; Dec 13, 2005 at 02:32 PM.

Dec 13, 2005 | 02:31 PM

#34

Motorhead351

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Quote:

Originally Posted by Jefftopgun

Now I have a question, If you do a fair amount of upgrades, will it be possible to just replace the injectors with slightly larger ones, and have the computer not realize it because everything "lines up" so to speak. Like if your motor performs on the same fuel curve as the stock motor did with the stock injectors, or is gonna be almost impossible to get things to line up like that?

Thanks

I would say its very much possible...but given the lack of hard data on the ford efi, as far as, modification = certain level of hp...it would be a shot in the dark.

Dec 13, 2005 | 03:00 PM

#35

Jefftopgun

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whats the margin of error? How far will the stock computer go on either side before it starts throwing codes because it knows somethings up.

Dec 13, 2005 | 03:01 PM

#36

Jefftopgun

Mountain Pass

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oops, double post

Last edited by Jefftopgun; Dec 13, 2005 at 03:01 PM. Reason: double post, plz delete

Dec 13, 2005 | 03:26 PM

#37

Silver Streak

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From: Broken Arrow, OK

Most stock computers can alter fuel curves by at least 30-40% in extreme cases.

To answer your question about larger injectors, the computer will not just go about it's business without noticing them. You will end up with no benefit. The WOT fuel curve is guessed at based on the part throttle curve learned in closed loop. With larger injectors the computer will learn to lean it down at part throttle and will then assume that it needs leaned down at WOT as well. You can trick it with an adjustable pressure regulator. 19 lb injectors and an adjustable regulator can be made to flow less fuel with vacuum applied to the regulator to trick the computer into richening the WOT curve. Those same injectors will flow more than the stockers with no vacuum to the regulator, so you are getting extra fuel from that as well.

Dec 13, 2005 | 03:30 PM

#38

Motorhead351

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Disregard the below..seems SS beat me to it...

Don't quote me on this...but the figures 15-20% have been thrown around...most think if you upgrade the stock engine to have 15-20% more hp than stock, then your likely to run lean enough to cause concern.

Thats kinda of a broad statement though, cause there is no telling where your gonna end up...with the hp or your injector lbhr/fuel psi

I'd say 15-20% either way, rich or lean, might be a fair statement.

So I would "guess", ideally you'd have your fuel psi somewhere around 49psi, this way you have room to lean or richen and not be too..high or too low.

OR you could go with a standalone efi controller (megasquirt) and control everything with your PC, datalog with a wideband/ tune on the fly, then you know exactly whats happening and not have to flip the bill for dyno sessions.

However, really think this option through if you have emissions testing.

Last edited by Motorhead351; Dec 13, 2005 at 03:32 PM.