"A Trim" on Speed Density?

Discussion in 'Fox 5.0 Mustang Tech' started by jaymac, Aug 15, 2005.


  1. txstang84

    txstang84 Active Member

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    i was sure i'd read somewhere that anymore than 70-75psi on stock style injectors was enough to cause them to not flow properly and burn up the coil quicker due to the high effort req'd to open the pintle? anyone have any good data on this one?
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  2. Rick 91GT

    Rick 91GT SN Certified Technician Site Sponsor

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    Over 90% is pushing it, they have a tendency to stick open...then they are trash. It is best to keep them around 80-85% duty cycle...
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  3. txstang84

    txstang84 Active Member

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    ...i've read a little bit from fordfueljection.com about duty cycle, but how exactly do you determine that? or do you have to hook your car up to a datalogger during a dyno run?
    #23
  4. tmoss

    tmoss Gettin Wired Founding Member

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    Brainstorm (?) - You should be able to get a VERY close idea by monitoring peak voltage at one of the injectors. 12vdc = 100% duty cycle, 90% = 10.8vdc, 80% = 9.6vdc. Most good multimeters today have a "peak hold" feature that might be able to be used by connecting it to an injector with pins through the wire like you do for the TPS (the meters are very high input impedance, so no ill effects to injector applied voltage would occur). No need to buy a TwEECer or other tuning hardware/software. The peak voltage would be the highest value (highest duty cycle) seen at the injector.
    #24
  5. iblue

    iblue New Member

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    Ive known guys who have ran 24lb/hr injectors out of the NA cobra's in their turbo neons with max fuel pressure of 100-110psi for 20k+ miles without issue. I don't know how it does in the longer run. But I would completely agree that is is not the optimum way to do this. Ultimately you would want complete control over fuel and to adjust duty cycle based on airflow but for that you should just go to a mass air setup.
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  6. 352Ford2

    352Ford2 New Member

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