SPREADSHEET: Fuel pump flow vs. Injector flow

02rexwi · **Joined:** Wed Jul 16, 2008 11:32 pm **Posts:** 324

Here's a spreadsheet I made up to compare the fuel pump flow to the flow of your injectors at various duty cycles. As most people know, the duty cycle that the ECU throws out isn't the actual duty cycle since it can give value over 100%, so keep that in mind when using the sheet. The sheet was made as a way to properly size your fuel system for high horsepower E85 vehicles since they demand more fuel flow than gasoline car.
There are instructions on the first page on how to use the sheet, I dont know how to make those buttons in excell to do the steps for you, but if someone would like to show me how I'd be happy to add them in.
The default flows are set up for injector dynamics 1000cc bosch injectors and a single in tank walbro 255HP fuel pump.

Please let me know if there's anything you guys would like to see added into the spreadsheet or have changed for future versions.
-Mark

mickeyd2005 · **Joined:** Wed Oct 25, 2006 4:32 am **Posts:** 3040

Just FYI. The ecu doesn't use duty cycle. Duty cycle is something that is generated by the logger.

02rexwi · **Joined:** Wed Jul 16, 2008 11:32 pm **Posts:** 324

Good to know, do you know how it calculates it?

nsfw · **Joined:** Thu Nov 23, 2006 2:23 am **Posts:** 2565

Available pulse width is a function of RPM - it's the time between ignition events.

Actual pulse with is something you can log.

IDC is actual divided by available, expressed as a percentage.

If you open up logger.xml you can see the formula.

mickeyd2005 · **Joined:** Wed Oct 25, 2006 4:32 am **Posts:** 3040

This is in the logger.

<parameter id="P201" name="Injector Duty Cycle" desc="">
<depends>
<ref parameter="P8" />

<ref parameter="P21" />

</depends>
<conversions>
<conversion units="%" expr="(P8*P21)/1200" format="0.00" />
</conversions>
</parameter>

As you can see, IDC is not obtained from the ecu. It is calculated by the logger. P8 is engine speed and P21 is Injector Pulse width. So, there is really no need to ever log IDC. Just log IPW and calculate IDC using a spreadsheet.

02rexwi · **Joined:** Wed Jul 16, 2008 11:32 pm **Posts:** 324

Good to know, thanks for the schooling

Anyone have feedback on the spreadsheet?

GRawSTi · **Joined:** Tue Jan 31, 2012 2:18 am **Posts:** 22

Where do the values for Sheet1, Column E come from?

mrf582 · **Posted:** Fri Feb 24, 2012 11:24 pm

mickeyd2005 wrote:

This is in the logger.

<parameter id="P201" name="Injector Duty Cycle" desc="">
<depends>
<ref parameter="P8" />

<ref parameter="P21" />

</depends>
<conversions>
<conversion units="%" expr="(P8*P21)/1200" format="0.00" />
</conversions>
</parameter>

As you can see, IDC is not obtained from the ecu. It is calculated by the logger. P8 is engine speed and P21 is Injector Pulse width. So, there is really no need to ever log IDC. Just log IPW and calculate IDC using a spreadsheet.

so you're saying that if you're logging ipw and rpm, logging idc as well doesn't cause the sample rate to get any slower?

dschultz · **Posted:** Sat Feb 25, 2012 4:39 pm

Nope, shouldn't as it's just a calculation based on those other items.

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SPREADSHEET: Fuel pump flow vs. Injector flow

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