BPW and Injector math

[Tbrendal]

I've got about a bazillion hours into learning spreadsheets. Almost 13 hours into edits in this one recorded in the file.

Special Thanks to Dave W at Old School EFI for sharing his BLM spreadsheets, they are all included.

For evaluation only! I've tested till I'm blind and it all seems to work properly. Warning, spreadsheet on steroids! If it passes inspection I think it's worthy of GearHead-EFI.com name...

EDIT: New upload with protection issue on Injector Duty Cycle fixed.

I tried using your calculator but the content does not work . For some reason I am losing all the formulas attached to the spreadsheet. Help!!!

[dave w]

I tried using your calculator but the content does not work . For some reason I am losing all the formulas attached to the spreadsheet. Help!!!

Tbrendal, It saddens me to tell you, EagleMark lost his battle with cancer and passed away just over a year ago.

I'll try helping you with spreadsheet. I need to know the post # of the spreadsheet you are using.

dave w

[Tbrendal]

Damn! I'm sorry to here that. I feel like I know the guy after reading all the work he has done here for us. Of course I guess it is nice to know his legacy lives on!!!

[Tbrendal]

It post # 18 of this thread.

[dave w]

It post # 18 of this thread.

The spreadsheet in post #18 is an Open Office .ods file: https://www.openoffice.org/ if you want to download and use freeware Open Office.

Post # 20 has a Microsoft Excel .xls file if you have Excel. I've also re-attached the file from Post #20, see below. I just tried using the attached .xls, seems to be working for me.

Please update me with your progress.

dave w

[Tbrendal]

Thanks Dave!. I didn't notice it wasn't an excell document.
First let me give you my specs.
I have a .030 350 block with the stock dish pistons, RV cam, Vortec heads with an air gap intake manifold. Im running the 5.7 throttle body that has all the ultimate mods done. 18 PSI spring and a 40 PSI in tank fuel pump. My truck runs the 7747 ECM. I started with an ASDU stock bin with the highway fuel added to it provided by Eagle Mark!
I did the math and have set my BPW to 104. I had a heck of a time before resetting that. My injectors were running at 100% duty cycle all the time. Once I put the 104 in the BPW it came down to where it should be. I will finally log some good data on the way home tonight! I also changed the ASDU stock BIN over to a Vortec head timing curve. Other than that I have not made any changes yet.

Sorry to hear about Eagle Mark again. That guy was quite the innovator !

[Tbrendal]

How do you copy the BLM table from a log on tunerpro? or do you have to enter all the values manually?

[dave w]

Are you using the running average from the TunerPro RT history tables?

Highlight the cells, then press down on both the Ctrl and "C" (Control C) on the keyboard to copy the averages. To paste, press down both Ctrl and "V" (Control V) on the keyboard.

dave w

[350yj]

The spreadsheet in post #18 is an Open Office .ods file: https://www.openoffice.org/ if you want to download and use freeware Open Office.

Post # 20 has a Microsoft Excel .xls file if you have Excel. I've also re-attached the file from Post #20, see below. I just tried using the attached .xls, seems to be working for me.

Please update me with your progress.

dave w

Using this spreadsheet, running 100% duty cycle on my injectors indicates a supported horsepower of 306. I feel I have been wronged. I purchased a rebuilt TBI unit from SPR performance, specs below:

46mm TBI Kit
New TPS, New IAC, TPS adapter, 65lb flow-matched injectors, 18psi spring, thinned shaft, bushed shaft, 1/4" pod spacer, shaved air horns, adj reg cover, custom cut 46mm base gasket

I specified I was using a kit from Summit Racing (SME-K-355-400), link to cam specifics here. I'm considering selling all the GM TBI parts and going for an MPFI self learning kit from Fast.

--
Kris

[Tbrendal]

I am by no means an expert but running your injectors at 100% is not good. You need to increase your BPW

[350yj]

IIRC, this is a zero sum game; increasing the BPW or increasing the duty cycle from the injectors. Either way, the amount of time the injectors are firing is the same.

--
Kris

[dave w]

One of my 5.7 liter TBI tuned engines ('7427 PCM using a Wide Band O2 Sensor to tune with) went on a Dyno ... the results were 330 RWHP using 65 cop car injectors with a stock fuel pressure regulator spring and 670 CFM (50mm Throttle Body).

The FAST system might be an option. I would use a '7427 PCM in MPFI mode. Personally, I fell I can tune better than the self learning FAST system.

dave w

[350yj]

Thanks for your reply Dave. I feel like I *could* tune better than a FAST or Holley MPFI system with enough time and trial and error. I have had this setup for over a year and not had the time to learn enough to make a perfectly drivable bin IMO. However, I feel as though there are some limitations to the 1227747 $42 ECM that can't be solved such as:

Inability to correct using a wide band
Low-resolution fuel/spark tables
Slow sensor polling intervals

The FAST or Holley MPFI kits are not cheap and do require standalone Ignition controls. Probably total parts cost of 4 grand. On the plus side, there is now a one to one relationship with the injector and cylinder. I would really like the current TBI system to run as smoothly as my daily driver but feel as though I am currently overwhelmed with tuning and have a need of my Jeep being ready for the winter.

Lastly, I feel as though the Holley or FAST kit would net me better fuel economy. Currently averaging 10 MPG with this setup in a 1990 Jeep Wrangler YJ which weighs in around 3300 pounds. I have the motor bolted up to the stock AX15 5 speed with a custom bellhousing, 4.10 gears and 35 inch tires. It will run around 2k RPM doing 70. The MPG isn't the problem so much so is the 15 gallon fuel tank. My commute into work is 80 miles round trip and having to fill up every day is annoying.

--
Kris