Injector Slopes

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M90 Ranger
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Injector Slopes

Post by M90 Ranger » Thu Dec 06, 2007 8:07 am

Excellent Software!
I'm a little fuzzy on the injector slopes however.
If I understand correctly the high slope is the lb/hr rating correct?
The part where I get confused is when I load my stock file.
It reads High Slope 36 and Low 24.
The vehicle has 19lb injectors in it stock.
If I load a SF modified file w/30lb and compare it to stock, the SF file reads 30 High.
This isn't a problem cuz I am still using the stock injectors, but how would I make corrections If I were to change them?
Vehicle is a flex fuel (if it makes a difference)
Box code HCL6
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Re: Injector Slopes

Post by M90 Ranger » Thu Dec 06, 2007 4:09 pm

Anybody?
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Mattr66
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Re: Injector Slopes

Post by Mattr66 » Thu Dec 06, 2007 4:39 pm

Usually the High Slope is the actual rating of the injector at the base fuel pressure. The low slope is the bigger number because the injector will act larger than it really is at low pulsewidths so you tell the pcm the injector is larger. The breakpoint is the pulsewidth that the pcm switches from the low to high slope.

Hope this helps.
Matt R
Matt Robinson
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www.gearheadautomotiveperformance.com

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Re: Injector Slopes

Post by M90 Ranger » Thu Dec 06, 2007 5:34 pm

I get that much.
I don't understand why my Stock High Slope is 36 When my stock injectors are 19lb
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Re: Injector Slopes

Post by Mattr66 » Thu Dec 06, 2007 5:52 pm

possible error in the template maybe? The low slope should always be higher valued than the high slope....
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Re: Injector Slopes

Post by M90 Ranger » Thu Dec 06, 2007 9:06 pm

OK I f!!!!d up
High is 23 and LOW is 36.
Shouldn't High be closer to 19?
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Re: Injector Slopes

Post by Mattr66 » Thu Dec 06, 2007 9:14 pm

depends.... my expedition has a mechanical returnless fuel system that runs higher pressure so the part number could be 19lb at 45 psi but run higher fuel pressure so the injector slopes would be set for the flow rating at the pressure the system runs at..... Just a guess....

Matt R
Matt Robinson
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www.gearheadautomotiveperformance.com

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Re: Injector Slopes

Post by geoffav » Thu Dec 06, 2007 10:00 pm

Interesting, I learn something everytime I sign on. 8-)
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Re: Injector Slopes

Post by M90 Ranger » Thu Dec 06, 2007 10:37 pm

You are correct!
Rated at 43.5psi. running at 55psi..
Psi diff = 21.5lb inj per general formula.
http://users.erols.com/srweiss/calcpchg.htm
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Re: Injector Slopes

Post by Mattr66 » Thu Dec 06, 2007 11:40 pm

Well as Hannibal in the A-Team says "I love it when a plan comes together"

Matt R
Matt Robinson
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